Dominion Astrophysical Observatory

 

The Dominion Observatory operated from 1902 to 1970. The observatory grew out of the need for the precise coordinates and timekeeping that at that time could only come from an observatory. Chief Dominion Architect David Ewart designed the Dominion Observatory in 1902.

 

This Romanesque Revival building was completed in 1905. Its main instrument was a 15-inch refracting telescope, the largest refracting telescope ever installed in Canada. While the building and institution were primarily dedicated to astronomical timekeeping in support of surveying, a number of other activities took place here. The Dominion Observatory was Canada's leading institution in Geophysics for many decades, which included the operation of Canada's national seismometer network. The facility did important work but with this bridgehead into the world of astronomy and the growth of the field of astrophysics Canadian astronomers quickly demanded a facility designed for the new scientific age. In 1917, the Dominion Astrophysical Observatory was opened in Victoria, B.C. and it supplanted the Dominion Observatory as Canada's foremost astronomical observatory. For many years the Dominion Observatory was best known to Canadians as the source of Canada's official time signal.

 

The observatory continued in operation until 1970 at which time Canada's science institutions were reorganized. The national time-keeping and astronomical activities were transferred to the National Research Council of Canada, while the geophysics, surveying and mapping were transferred to the Department of Energy Mines and Resources. The Geophysics work was later merged into the Geological Survey of Canada, now part of Natural Resources Canada. Astronomical timekeeping observations at the Dominion Observatory had ceased many years prior to this, when crystal oscillator clocks and later atomics clocks were found to be superior to astronomical timekeeping. The building became home to NRCan offices. The telescope had been open for public viewing from 1905 until 1970. In 1974, the telescope was moved from the Dominion Observatory to the Helen Sawyer Hogg Observatory at the Canada Science and Technology Museum where it remains to this day.

 

The Central Experimental farm is a place in Ottawa that I really love to visit, in any season. It has beautiful 19th century buildings, gorgeous gardens, an amazing Arboretum and much more. It is the only working farm right in the heart of any world capital. It has been doing agricultural research since 1886, so it is both a scientific and recreational facility.

 

Il ragno vespa è una specie di ragno, così denominato per la colorazione dell'addome giallo e nera simile alla colorazione delle vespe. Viene anche chiamato comunemente ragno tigre, epeira fasciata, ragno zebra o argiope fasciata.

Il ragno vespa non è aggressivo, se disturbato mette in atto una strategia difensiva molto particolare: rimanendo al centro della tela, le imprime un movimento oscillatorio molto rapido, per un tempo che può variare dai 15 ai 30 secondi. Se questa tattica di "dissuasione" non ha effetto sceglie la fuga pur rimanendo nei paraggi fino a minaccia cessata. In caso di eventuale morso, gli effetti del veleno sono blandi; si avverte il dolore causato dall’azione meccanica dei cheliceri e un arrossamento della parte interessata. I sintomi scompaiono nell’arco di alcune ore

Una curiosità si ha nell'accoppiamento di tali aracnidi, infatti quasi sempre le femmine di questi ragni uccidono i loro pretendenti maschi, a meno che questi ultimi non riescano a fuggire prima; spesso nel tentativo di fuga il pene degli individui maschi si spezza all'interno delle femmine, non permettendo che altri ragni fecondino la stessa, e assicurandosi così il successo

notizie da wikipedia.

whytake.net/Portfolio/ElioDestefani/1415

Neues Rathaus/Wurmeck - München

"Die westliche Ecke zur Weinstraße heißt "Wurmeck". Zwei Deutungen des Namens sind möglich: die eine leitet ihn her vom Hausnamen einer Metzgerfamilie Wurm, die im 13.Jh. das Eckhaus Weinstraße/Marienplatz bewohnte; wahrscheinlich ist er aber auf ein früher hier angebrachtes Fresko, das den Drachenkampf des hl. Georg zeigte, zurückzuführen.

Im Zusammenhang mit dem Bau des Neuen Rathauses entstand am Rathauseck die Plastik eines großen, sich windenden bronzenen Lindwurms mit Drachenkopf, Adlerklauen und riesigen Fledermausflügeln. Der Sage nach soll ein solches schreckliches Ungeheuer die Pest in alle Gassen und Wohnungen der Bürger geblasen haben, welche sich daraufhin in ihren Häusern einschlossen. Als sich der Lindwurm wieder einmal am Wurmeck niederließ, gelang es den Männern der Hauptwache, ihn mit einem einzigen Kanonenschuss zu töten. Aus Freude über die Tötung des pestbringenden Drachen sollen die Schäffler (Fassbinder, Böttcher, Küfer) ihren Schäfflertanz am "Wurmeck" aufgeführt haben. Bei diesem Zunfttanz bewegen sich 18 Reifenschwinger in schmucker Tracht, mit bogenförmigen Girlanden in der Hand, im Polkaschritt. Zwischen Tänzern und Zuschauern springt der Kasperl umher und schwärzt jungen Mädchen und Kindern die Nase, was an die Pest, den "Schwarzen Tod" erinnern soll. Obwohl das Ungeheuer getötet worden war, wagte sich, so die Sage, niemand auf die Straße. Fenster und Türen blieben verschlossen. Da zogen die mutigen Schäffler vor die Häuser, führten Freudentänze auf und lockten mit ihren Späßen die Bewohner aus ihren dunklen Wohnungen. Als Dank dafür wird der Schäfflertanz alle sieben Jahre zu Fasching in den Straßen der Stadt aufgeführt. Sie sind mit ihrem Tanz auch als Figuren am Glockenspiel des Rathausturmes zu sehen. Die lokale Überlieferung, wonach der Schäfflertanz auf eine Pestepidemie des Jahres 1517 zurückgehen soll, hat sich als nicht stichhaltig erwiesen. In München wird er seit dem frühen 19. Jh. gepflegt und gilt als ein "Markenzeichen" der Stadt." (Buch - der schwarze Führer Deutschlands)

 

New city hall/worm-hit a corner - Munich "the western corner to the crying race is called" worm-hits a corner ". Two interpretations of the name are possible: the one leads it ago from the house name of a butcher family worm, which inhabited the eckhaus crying race/Marienplatz in the 13.Jh.; probably it is however on a Fresko attached in former times here, which showed the kite fight hl. George to lead back. In connection with the building of the new city hall the plastics of a large, for winding bronze Lindwurms with drachenkopf, developed eagle claws and enormous fledermausfluegeln to city hall-hits a corner. After the legend such a terrible monster is to have blown the plague in all lanes and dwellings of the citizens, who itself thereupon in their houses included. When the Lindwurm again once to worm-hit a corner yourself established, it succeeded to the men of the police headquarters to kill it with only one cannon shot. From joy over the toetung kite plague-bringing is the Schaeffler (barrel binder, boettcher, Kuefer) its Schaefflertanz to "worm-hits a corner" to have specified. With this guild dance 18 tire oscillators in neat tracht, with arc-shaped girlanden in the hand, in the Polkaschritt move. Between dancers and spectators the Kasperl jumps around and blackens young girls and children the nose, which to the plague, which is to remind "black death". Although the monster had been killed, so the legend, anybody did not dare itself on the road. Windows and doors remained locked. There the courageous Schaeffler pulled before the houses, specified joy dances and lured with their fun the inhabitants from their dark dwellings. As thanks for it the Schaefflertanz is specified every seven years to carnival in the roads of the city. They are to be seen with their dance also as figures at the bell play of the city hall tower. The local excessive quantity, according to which the S

Steam yacht Thelma, photographed in 1904. My colorization of an image in the Library of Congress archive (Detroit Publishin Co. collection).

Three years later Thelma made made history. The world´s first ship-to-shore broadcast was made from the yacht.

Electrical World reported on August 10, 1907:

"The first actual application of radio-telephony to practical work anywhere in the world was made at Put-in-Bay, in Lake Erie, during the week of July 15 to 20, in reporting the regatta of the Interlake Association. The Radio Telephone Company installed the De Forest wireless telephone on board of the cruiser yacht "Thelma," and also equipped a shore station at the Fox Dock at Put-in-Bay.

The "Thelma" followed the competing yachts around the course through most of the races and full and graphic accounts were telephoned into the shore station.

The greatest distance at which the reports from the yachts were heard and recorded was four miles, considered remarkable in view of the height of "Thelma's" spars and the power of the transmitter on board. Her equipment comprised a 220-volt generator of 1 kilowatt capacity, the DeForest oscillator and transmitter, and for the receiving apparatus an audion detector and "pan cake" form of syntonizer or tuner. Her aerial wires led through the roof of the wheelhouse to a small crossarm on top of the foremast and thence to a similar arm on the mainmast. Ground connection was at first made to the propeller shafts of her twin screws, but as this was found insufficient, more area was added by fastening two sheets of zinc to the yacht's hull at the bow.

The telephone dynamo was belted direct to the flywheel of her starboard engines, aft, and the rest of the radio apparatus was mounted on a small table in her main cabin convenient to all.

On shore 110-volt direct-current was available and this was transformed to 220 volts by a motor generator. The current was led through a rheostat and choke coils to the oscillator. Connected to this oscillator is a shunt circuit consisting of a condenser of peculiar construction and a primary coil, the exact number of turns of which could be varied at will to alter the tune or wave length of the electrical waves which were generated. A second coil within this primary had its upper end connected direct with the antennae or aerial wire, while its lower end led first through the microphone transmitter and thence to the earth plate. In this way the changes in resistance in the microphone produced by the modulations of the human voice directly affect the intensity of the high-frequency currents which are continually passing from the air wire to the ground plate. Inasmuch as the receiver instrument is affected exactly in proportion with the strength of the received electric waves, it is evident that every variation in the microphone resistance by the voice will be reproduced to the listening ear at the distant station by the vibration of the telephone diaphragm there. The microphone transmitter and the telephone receiver are exactly the same as used in the wire telephone, with which all are familiar. The "oscillator" and the "responder" are the only new and additional features, and the ether takes the place of the connecting wire.

Upon the finish of the regatta the telephone apparatus from the "Thelma" and the Put-in-Bay shore station was shipped to Toledo, where it is the intention of the Radio Telephone Company to install it permanently, where it can be in communication with other wireless telephone sets to be installed on vessels sailing Lake Erie. The Great Lakes offer, perhaps, the most promising field anywhere in the world for the first general application of this new invention to the needs of a merchant marine, and it is the intention of the company to at once enter this promising field."

Electrical World, August 10, 1907

Generative drawing with particles, attractors, repelers and oscillators.

 

Ref: 171017_131022

Longtime customer Herr Kringle came a knockin’ again this year with another epic custom build request. To address a new level of intercontinental delivery challenges this season, we sourced a clean J80 Land Cruiser and upgraded everything, starting with the powertrain.

 

Kringle Spec features a raucous 600 HP delivered to all four wheels through a twin-turbocharged 4.0L V8 coupled with a 16KW plug in hybrid dual motor setup configured to pwn even the biggest obstacles terra firma can conjure.

 

The package is completed by a Portable roof-mounted SatNav Unit working in tandem with our custom Compact Trans-Dimensional Oscillator, enabling Herr Kringle to deliver even the most difficult packages in little more than the space of a wink.

 

I hope you enjoy, and Happy Holidays!

Moog Minitaur monophonic Bass synthesizer with yellow light up buttons for Square / Saw waves, Release & Glide.

''...Solo, in mezzo alla spiaggia, Bartleboom guardava. A piedi nudi, i pantaloni

arrotolati in su per non bagnarli, un quadernone sotto il braccio e un cappello di lana

in testa. Leggermente chinato in avanti, guardava: per terra. Studiava l’esatto punto in

cui l’onda, dopo essersi rotta una decina di metri più indietro, si allungava - divenuta

lago, e specchio e macchia d’olio - risalendo la delicata china della spiaggia e

finalmente si arrestava - l’estremo bordo orlato da un delicato perlage - per esitare un

attimo e alfine, sconfitta, tentare una elegante ritirata lasciandosi scivolare indietro,

lungo la via di un ritorno apparentemente facile ma, in realtà, preda destinata alla

spugnosa avidità di quella sabbia che, fin li imbelle, improvvisamente si svegliava e,

la breve corsa dell’acqua in rotta, nel nulla svaporava.

Bartleboom guardava.

Nel cerchio imperfetto del suo universo ottico la perfezione di quel moto

oscillatorio formulava promesse che l’irripetibile unicità di ogni singola onda

condannava a non esser mantenute. Non c’era verso di fermare quel continuo

avvicendarsi di creazione e distruzione. I suoi occhi cercavano la verità descrivibile e

regolamentata di un’immagine certa e completa: e finivano, invece, per correre dietro

alla mobile indeterminazione di quell’andirivieni che qualsiasi sguardo scientifico

cullava e derideva.

Era seccante. Bisognava fare qualcosa. Bartleboom fermò gli occhi. Li puntò davanti

ai piedi, inquadrando un pezzo di spiaggia muto e immobile. E decise di aspettare.

Doveva finirla di correre dietro a quell'altalena sfinente. Se Maometto non va alla

montagna, eccetera eccetera, pensò. Prima o poi sarebbe entrato - nella cornice di

quello sguardo che lui immaginava memorabile nella sua scientifica freddezza - il

profilo esatto, orlato di schiuma, dell’onda che aspettava. E li, essa si sarebbe fissata,

come un’impronta, nella sua mente. E lui l’avrebbe capita. Questo era il piano. Con

totale abnegazione Bartleboom si calò in un’immobilità senza sentimenti,

trasformandosi, per così dire, in neutrale ed infallibile strumento ottico. Quasi non

respirava. Nel cerchio fisso ritagliato dal suo sguardo calò un silenzio irreale, da

laboratorio. Era come una trappola, imperturbabile e paziente. Aspettava la sua preda.

E la preda, lentamente arrivò. Due scarpe da donna. Alte, ma da donna.

— Voi dovete essere Bartleboom.

Bartleboom, veramente, aspettava un’onda. O qualcosa del genere. Alzò lo sguardo e

vide una donna, chiusa in un elegante mantello viola.

— Bartleboom, sì... professor Ismael Bartleboom.

— Avete perso qualcosa?

Bartleboom si rese conto che se ne era rimasto chino in avanti, ancora irrigidito nello

scientifico profilo dello strumento ottico in cui si era tramutato. Si raddrizzò con tutta

la naturalezza di cui fu capace. Pochissima.

— No. Sto lavorando.

— Lavorando?

— Sì, faccio... faccio delle ricerche, sapete, delle ricerche...

— Ah.

— Delle ricerche scientifiche, voglio dire...

— Scientifiche.

— Sì.

Silenzio. La donna si strinse nel suo mantello viola.

— Conchiglie, licheni, cose del genere?

— No, onde.

Così: onde.

— Cioè... vedete lì, dove l’acqua arriva... sale sulla spiaggia poi si ferma... ecco,

proprio quel punto, dove si ferma... dura proprio solo un attimo, guardate, ecco, ad

esempio, lì... vedete che dura solo un attimo, poi sparisce, ma se uno riuscisse a

fermare quell'attimo... quando l’acqua si ferma, proprio quel punto, quella curva... è

quello che io studio. Dove l’acqua si ferma.

— E cosa c’è da studiare?

— Be’, è un punto importante... a volte non ci si fa caso, ma se ci pensate bene lì

succede qualcosa di straordinario, di... straordinario.

— Veramente?

Bartleboom si sporse leggermente verso la donna. Si sarebbe detto che avesse un

segreto da dire quando disse

— Lì finisce il mare.

Il mare immenso, l’oceano mare, che infinito corre oltre ogni sguardo, l’immane

mare onnipotente - c’è un luogo dove finisce, e un istante - l’immenso mare, un luogo

piccolissimo e un istante da nulla. Questo, voleva dire Bartleboom..''

(Alessandro Baricco)

 

-----

 

Soundtrack

Longtime customer Herr Kringle came a knockin’ again this year with another epic custom build request. To address a new level of intercontinental delivery challenges this season, we sourced a clean J80 Land Cruiser and upgraded everything, starting with the powertrain.

 

Kringle Spec features a raucous 600 HP delivered to all four wheels through a twin-turbocharged 4.0L V8 coupled with a 16KW plug in hybrid dual motor setup configured to pwn even the biggest obstacles terra firma can conjure.

 

The package is completed by a Portable roof-mounted SatNav Unit working in tandem with our custom Compact Trans-Dimensional Oscillator, enabling Herr Kringle to deliver even the most difficult packages in little more than the space of a wink.

 

I hope you enjoy, and Happy Holidays!

Interior view, selenium rectifier on voltage-doubler power supply below the chassis. 1933. This has a triode audio output valve. The frequency changer is a pentode valve biased at 0v so that hetrodyning is carried out by half-wave rectification of the received signal being further modulated by the valve configured as an oscillator. This is less efficient than true multiplicative mixing achieved by valves with two control grids such as a hexode.

Used in the artbook of Sascha Müller's well tempered Oscillator EP

 

Longtime customer Herr Kringle came a knockin’ again this year with another epic custom build request. To address a new level of intercontinental delivery challenges this season, we sourced a clean J80 Land Cruiser and upgraded everything, starting with the powertrain.

 

Kringle Spec features a raucous 600 HP delivered to all four wheels through a twin-turbocharged 4.0L V8 coupled with a 16KW plug in hybrid dual motor setup configured to pwn even the biggest obstacles terra firma can conjure.

 

The package is completed by a Portable roof-mounted SatNav Unit working in tandem with our custom Compact Trans-Dimensional Oscillator, enabling Herr Kringle to deliver even the most difficult packages in little more than the space of a wink.

 

I hope you enjoy, and Happy Holidays!

Using only drums and processed cassettes, and incorporating many elements of avant-garde music and sound art in their realisation, Sly & The Family Drone are a primal orchestra of drum rhythms, radiophonic oscillator noise and electronically-abstracted vocals.

Il ragno vespa (Argiope bruennichi Scopoli, 1772) è una specie di ragno, così denominato per la colorazione dell'addome giallo e nera simile alla colorazione delle vespe. Viene anche chiamato comunemente ragno tigre, epeira fasciata, ragno zebra o argiope fasciata.

Le femmine misurano circa 2–5 cm, i maschi circa la metà o anche meno. La livrea delle femmine ha una caratteristica colorazione a strisce gialle e nere a cui si deve il nome comune della specie. I maschi, invece, sono caratterizzati da colori scuri e molto più uniformi.

Il ragno vespa non è aggressivo, se disturbato mette in atto una strategia difensiva molto particolare: rimanendo al centro della tela, le imprime un movimento oscillatorio molto rapido, per un tempo che può variare dai 15 ai 30 secondi. Se questa tattica di "dissuasione" non ha effetto sceglie la fuga pur rimanendo nei paraggi fino a minaccia cessata. In caso di eventuale morso, gli effetti del veleno sono blandi; si avverte il dolore causato dall’azione meccanica dei cheliceri e un arrossamento della parte interessata. I sintomi scompaiono nell’arco di alcune ore.

Una curiosità si ha nell'accoppiamento di tali aracnidi, infatti quasi sempre le femmine di questi ragni uccidono i loro pretendenti maschi, a meno che questi ultimi non riescano a fuggire prima; spesso nel tentativo di fuga il pene degli individui maschi si spezza all'interno delle femmine, non permettendo che altri ragni fecondino la stessa, e assicurandosi così il successo riproduttivo.

Questo tipo di ragno è diffuso in gran parte d'Europa. Vivono in quasi tutti gli ambienti, e molto importante per questa specie e avere lo spazio necessario per la costruzione della sua ampia tela: luoghi prediletti per l'edificazione delle ragnatele sono gli arbusti.

 

A winter landscape out the window. The unassembled pieces of Tatyana’s terrible machine laying neglected in the corner.

“It’s too cold to play outside, we could at least build my Oscillator.”

“Taty, I really want to play snow queen, and the weather is perfect for it inside or outside!”

“Look, unless you get more people YOU have to be Kay. You can NOT be the snow queen. Again. It’s MY turn this time.”

Wiki tells me that Telechron made clocks between 1912 and 1992,with the most market presence between 1925 and 1955. Their electric clocks were distinct because time was synchronized using oscillators that responded to alternating current from the power grid. The product line was influenced by the Art Deco movement, which can be seen here in the decorations around the clock (which may not have been a Telechron product), and, more subtly, in the numbers on the clock face.

This radio was placed on ships to entertain the troops and at the same time evade detection by the enemy. Enemy submarines could pick up (receive) the weak signal put out by the oscillator in a receiver and thus locate a ship. This unit prevented this partly by excessive shielding.

Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10−23 Hz−1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

 

Keywords: Terrestrial gravity, Newtonian noise, Wiener filter, Mitigation

Go to:

Introduction

In the coming years, we will see a transition in the field of high-precision gravimetry from observations of slow lasting changes of the gravity field to the experimental study of fast gravity fluctuations. The latter will be realized by the advanced generation of the US-based LIGO [1] and Europe-based Virgo [7] gravitational-wave (GW) detectors. Their goal is to directly observe for the first time GWs that are produced by astrophysical sources such as inspiraling and merging neutron-star or black-hole binaries. Feasibility of the laser-interferometric detector concept has been demonstrated successfully with the first generation of detectors, which, in addition to the initial LIGO and Virgo detectors, also includes the GEO600 [119] and TAMA300 [161] detectors, and several prototypes around the world. The impact of these projects onto the field is two-fold. First of all, the direct detection of GWs will be a milestone in science opening a new window to our universe, and marking the beginning of a new era in observational astronomy. Second, several groups around the world have already started to adapt the technology to novel interferometer concepts [60, 155], with potential applications not only in GW science, but also geophysics. The basic measurement scheme is always the same: the relative displacement of test masses is monitored by using ultra-stable lasers. Progress in this field is strongly dependent on how well the motion of the test masses can be shielded from the environment. Test masses are placed in vacuum and are either freely falling (e.g., atom clouds [137]), or suspended and seismically isolated (e.g., high-quality glass or crystal mirrors as used in all of the detectors listed above). The best seismic isolations realized so far are effective above a few Hz, which limits the frequency range of detectable gravity fluctuations. Nonetheless, low-frequency concepts are continuously improving, and it is conceivable that future detectors will be sufficiently sensitive to detect GWs well below a Hz [88].

 

Terrestrial gravity perturbations were identified as a potential noise source already in the first concept laid out for a laser-interferometric GW detector [171]. Today, this form of noise is known as “terrestrial gravitational noise”, “Newtonian noise”, or “gravity-gradient noise”. It has never been observed in GW detectors, but it is predicted to limit the sensitivity of the advanced GW detectors at low frequencies. The most important source of gravity noise comes from fluctuating seismic fields [151]. Gravity perturbations from atmospheric disturbances such as pressure and temperature fluctuations can become significant at lower frequencies [51]. Anthropogenic sources of gravity perturbations are easier to avoid, but could also be relevant at lower frequencies [163]. Today, we only have one example of a direct observation of gravity fluctuations, i.e., from pressure fluctuations of the atmosphere in high-precision gravimeters [128]. Therefore, almost our entire understanding of gravity fluctuations is based on models. Nonetheless, potential sensitivity limits of future large-scale GW detectors need to be identified and characterized well in advance, and so there is a need to continuously improve our understanding of terrestrial gravity noise. Based on our current understanding, the preferred option is to construct future GW detectors underground to avoid the most dominant Newtonian-noise contributions. This choice was made for the next-generation Japanese GW detector KAGRA, which is currently being constructed underground at the Kamioka site [17], and also as part of a design study for the Einstein Telescope in Europe [140, 139]. While the benefit from underground construction with respect to gravity noise is expected to be substantial in GW detectors sensitive above a few Hz [27], it can be argued that it is less effective at lower frequencies [88].

 

Alternative mitigation strategies includes coherent noise cancellation [42]. The idea is to monitor the sources of gravity perturbations using auxiliary sensors such as microphones and seismometers, and to use their data to generate a coherent prediction of gravity noise. This technique is successfully applied in gravimeters to reduce the foreground of atmospheric gravity noise using collocated pressure sensors [128]. It is also noteworthy that the models of the atmospheric gravity noise are consistent with observations. This should give us some confidence at least that coherent Newtonian-noise cancellation can also be achieved in GW detectors. It is evident though that a model-based prediction of the performance of coherent noise cancellation schemes is prone to systematic errors as long as the properties of the sources are not fully understood. Ongoing experiments at the Sanford Underground Research Facility with the goal to characterize seismic fields in three dimensions are expected to deliver first data from an underground seismometer array in 2015 (see [89] for results from an initial stage of the experiment). While most people would argue that constructing GW detectors underground is always advantageous, it is still necessary to estimate how much is gained and whether the science case strongly profits from it. This is a complicated problem that needs to be answered as part of a site selection process.

 

More recently, high-precision gravity strainmeters have been considered as monitors of geophysical signals [83]. Analytical models have been calculated, which allow us to predict gravity transients from seismic sources such as earthquakes. It was suggested to implement gravity strainmeters in existing earthquake-early warning systems to increase warning times. It is also conceivable that an alternative method to estimate source parameters using gravity signals will improve our understanding of seismic sources. Potential applications must still be investigated in greater detail, but the study already demonstrates that the idea to use GW technology to realize new geophysical sensors seems feasible. As explained in [49], gravitational forces start to dominate the dynamics of seismic phenomena below about 1 mHz (which coincides approximately with a similar transition in atmospheric dynamics where gravity waves start to dominate over other forms of oscillations [164]). Seismic isolation would be ineffective below 1 mHz since the gravitational acceleration of a test mass produced by seismic displacement becomes comparable to the seismic acceleration itself. Therefore, we claim that 10 mHz is about the lowest frequency at which ground-based gravity strainmeters will ever be able to detect GWs, and consequently, modelling terrestrial gravity perturbations in these detectors can focus on frequencies above 10 mHz.

 

This article is divided into six main sections. Section 2 serves as an introduction to gravity measurements focussing on the response mechanisms and basic properties of gravity sensors. Section 3 describes models of gravity perturbations from ambient seismic fields. The results can be used to estimate noise spectra at the surface and underground. A subsection is devoted to the problem of noise estimation in low-frequency GW detectors, which differs from high-frequency estimates mostly in that gravity perturbations are strongly correlated between different test masses. In the low-frequency regime, the gravity noise is best described as gravity-gradient noise. Section 4 is devoted to time domain models of transient gravity perturbations from seismic point sources. The formalism is applied to point forces and shear dislocations. The latter allows us to estimate gravity perturbations from earthquakes. Atmospheric models of gravity perturbations are presented in Section 5. This includes gravity perturbations from atmospheric temperature fields, infrasound fields, shock waves, and acoustic noise from turbulence. The solution for shock waves is calculated in time domain using the methods of Section 4. A theoretical framework to calculate gravity perturbations from objects is given in Section 6. Since many different types of objects can be potential sources of gravity perturbations, the discussion focusses on the development of a general method instead of summarizing all of the calculations that have been done in the past. Finally, Section 7 discusses possible passive and active noise mitigation strategies. Due to the complexity of the problem, most of the section is devoted to active noise cancellation providing the required analysis tools and showing limitations of this technique. Site selection is the main topic under passive mitigation, and is discussed in the context of reducing environmental noise and criteria relevant to active noise cancellation. Each of these sections ends with a summary and a discussion of open problems. While this article is meant to be a review of the current state of the field, it also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations (Sections 3.3.2 and 3.3.3), active gravity noise cancellation (Section 7.1.3), and timedomain models of gravity perturbations from atmospheric and seismic point sources (Sections 4.1, 4.5, and 5.3).

 

Even though evident to experts, it is worth emphasizing that all calculations carried out in this article have a common starting point, namely Newton’s universal law of gravitation. It states that the attractive gravitational force equation M1 between two point masses m1, m2 is given by

 

equation M21

where G = 6.672 × 10−11 N m2/kg2 is the gravitational constant. Eq. (1) gives rise to many complex phenomena on Earth such as inner-core oscillations [156], atmospheric gravity waves [157], ocean waves [94, 177], and co-seismic gravity changes [122]. Due to its importance, we will honor the eponym by referring to gravity noise as Newtonian noise in the following. It is thereby clarified that the gravity noise models considered in this article are non-relativistic, and propagation effects of gravity changes are neglected. While there could be interesting scenarios where this approximation is not fully justified (e.g., whenever a gravity perturbation can be sensed by several sensors and differences in arrival times can be resolved), it certainly holds in any of the problems discussed in this article. We now invite the reader to enjoy the rest of the article, and hope that it proves to be useful.

 

Go to:

Gravity Measurements

In this section, we describe the relevant mechanisms by which a gravity sensor can couple to gravity perturbations, and give an overview of the most widely used measurement schemes: the (relative) gravimeter [53, 181], the gravity gradiometer [125], and the gravity strainmeter. The last category includes the large-scale GW detectors Virgo [6], LIGO [91], GEO600 [119], KAGRA [17], and a new generation of torsion-bar antennas currently under development [13]. Also atom interferometers can potentially be used as gravity strainmeters in the future [62]. Strictly speaking, none of the sensors only responds to a single field quantity (such as changes in gravity acceleration or gravity strain), but there is always a dominant response mechanism in each case, which justifies to give the sensor a specific name. A clear distinction between gravity gradiometers and gravity strainmeters has never been made to our knowledge. Therefore the sections on these two measurement principles will introduce a definition, and it is by no means the only possible one. Later on in this article, we almost exclusively discuss gravity models relevant to gravity strainmeters since the focus lies on gravity fluctuations above 10 mHz. Today, the sensitivity near 10 mHz of gravimeters towards gravity fluctuations is still competitive to or exceeds the sensitivity of gravity strainmeters, but this is likely going to change in the future so that we can expect strainmeters to become the technology of choice for gravity observations above 10 mHz [88]. The following sections provide further details on this statement. Space-borne gravity experiments such as GRACE [167] will not be included in this overview. The measurement principle of GRACE is similar to that of gravity strainmeters, but only very slow changes of Earth gravity field can be observed, and for this reason it is beyond the scope of this article.

 

The different response mechanisms to terrestrial gravity perturbations are summarized in Section 2.1. While we will identify the tidal forces acting on the test masses as dominant coupling mechanism, other couplings may well be relevant depending on the experiment. The Shapiro time delay will be discussed as the only relativistic effect. Higher-order relativistic effects are neglected. All other coupling mechanisms can be calculated using Newtonian theory including tidal forces, coupling in static non-uniform gravity fields, and coupling through ground displacement induced by gravity fluctuations. In Sections 2.2 to 2.4, the different measurement schemes are explained including a brief summary of the sensitivity limitations (choosing one of a few possible experimental realizations in each case). As mentioned before, we will mostly develop gravity models relevant to gravity strainmeters in the remainder of the article. Therefore, the detailed discussion of alternative gravimetry concepts mostly serves to highlight important differences between these concepts, and to develop a deeper understanding of the instruments and their role in gravity measurements.

 

Gravity response mechanisms

 

Gravity acceleration and tidal forces We will start with the simplest mechanism of all, the acceleration of a test mass in the gravity field. Instruments that measure the acceleration are called gravimeters. A test mass inside a gravimeter can be freely falling such as atom clouds [181] or, as suggested as possible future development, even macroscopic objects [72]. Typically though, test masses are supported mechanically or magnetically constraining motion in some of its degrees of freedom. A test mass suspended from strings responds to changes in the horizontal gravity acceleration. A test mass attached at the end of a cantilever with horizontal equilibrium position responds to changes in vertical gravity acceleration. The support fulfills two purposes. First, it counteracts the static gravitational force in a way that the test mass can respond to changes in the gravity field along a chosen degree of freedom. Second, it isolates the test mass from vibrations. Response to signals and isolation performance depend on frequency. If the support is modelled as a linear, harmonic oscillator, then the test mass response to gravity changes extends over all frequencies, but the response is strongly suppressed below the oscillators resonance frequency. The response function between the gravity perturbation δg(ω) and induced test mass acceleration δa(ω) assumes the form

equation M32

where we have introduced a viscous damping parameter γ, and ω0 is the resonance frequency. Well below resonance, the response is proportional to ω2, while it is constant well above resonance. Above resonance, the supported test mass responds like a freely falling mass, at least with respect to “soft” directions of the support. The test-mass response to vibrations δα(ω) of the support is given by

 

equation M43

This applies for example to horizontal vibrations of the suspension points of strings that hold a test mass, or to vertical vibrations of the clamps of a horizontal cantilever with attached test mass. Well above resonance, vibrations are suppressed by ω−2, while no vibration isolation is provided below resonance. The situation is somewhat more complicated in realistic models of the support especially due to internal modes of the mechanical system (see for example [76]), or due to coupling of degrees of freedom [121]. Large mechanical support structures can feature internal resonances at relatively low frequencies, which can interfere to some extent with the desired performance of the mechanical support [173]. While Eqs. (2) and (3) summarize the properties of isolation and response relevant for this paper, details of the readout method can fundamentally impact an instrument’s response to gravity fluctuations and its susceptibility to seismic noise, as explained in Sections 2.2 to 2.4.

 

Next, we discuss the response to tidal forces. In Newtonian theory, tidal forces cause a relative acceleration δg12(ω) between two freely falling test masses according to

 

equation M54

where equation M6 is the Fourier amplitude of the gravity potential. The last equation holds if the distance r12 between the test masses is sufficiently small, which also depends on the frequency. The term equation M7 is called gravity-gradient tensor. In Newtonian approximation, the second time integral of this tensor corresponds to gravity strain equation M8, which is discussed in more detail in Section 2.4. Its trace needs to vanish in empty space since the gravity potential fulfills the Poisson equation. Tidal forces produce the dominant signals in gravity gradiometers and gravity strainmeters, which measure the differential acceleration or associated relative displacement between two test masses (see Sections 2.3 and 2.4). If the test masses used for a tidal measurement are supported, then typically the supports are designed to be as similar as possible, so that the response in Eq. (2) holds for both test masses approximately with the same parameter values for the resonance frequencies (and to a lesser extent also for the damping). For the purpose of response calibration, it is less important to know the parameter values exactly if the signal is meant to be observed well above the resonance frequency where the response is approximately equal to 1 independent of the resonance frequency and damping (here, “well above” resonance also depends on the damping parameter, and in realistic models, the signal frequency also needs to be “well below” internal resonances of the mechanical support).

 

Shapiro time delay Another possible gravity response is through the Shapiro time delay [19]. This effect is not universally present in all gravity sensors, and depends on the readout mechanism. Today, the best sensitivities are achieved by reflecting laser beams from test masses in interferometric configurations. If the test mass is displaced by gravity fluctuations, then it imprints a phase shift onto the reflected laser, which can be observed in laser interferometers, or using phasemeters. We will give further details on this in Section 2.4. In Newtonian gravity, the acceleration of test masses is the only predicted response to gravity fluctuations. However, from general relativity we know that gravity also affects the propagation of light. The leading-order term is the Shapiro time delay, which produces a phase shift of the laser beam with respect to a laser propagating in flat space. It can be calculated from the weak-field spacetime metric (see chapter 18 in [124]):

equation M95

Here, c is the speed of light, ds is the so-called line element of a path in spacetime, and equation M10. Additionally, for this metric to hold, motion of particles in the source of the gravity potential responsible for changes of the gravity potential need to be much slower than the speed of light, and also stresses inside the source must be much smaller than its mass energy density. All conditions are fulfilled in the case of Earth gravity field. Light follows null geodesics with ds2 = 0. For the spacetime metric in Eq. (5), we can immediately write

 

equation M116

As we will find out, this equation can directly be used to calculate the time delay as an integral along a straight line in terms of the coordinates equation M12, but this is not immediately clear since light bends in a gravity field. So one may wonder if integration along the proper light path instead of a straight line yields additional significant corrections. The so-called geodesic equation must be used to calculate the path. It is a set of four differential equations, one for each coordinate t, equation M13 in terms of a parameter λ. The weak-field geodesic equation is obtained from the metric in Eq. (5):

 

equation M147

where we have made use of Eq. (6) and the slow-motion condition equation M15. The coordinates equation M16 are to be understood as functions of λ. Since the deviation of a straight path is due to a weak gravity potential, we can solve these equations by perturbation theory introducing expansions equation M17 and t = t(0) +t(1) + …. The superscript indicates the order in ψ/c2. The unperturbed path has the simple parametrization

 

equation M188

We have chosen integration constants such that unperturbed time t(0) and parameter λ can be used interchangeably (apart from a shift by t0). Inserting these expressions into the right-hand side of Eq. (7), we obtain

 

equation M199

As we can see, up to linear order in equation M20, the deviation equation M21 is in orthogonal direction to the unperturbed path equation M22, which means that the deviation can be neglected in the calculation of the time delay. After some transformations, it is possible to derive Eq. (6) from Eq. (9), and this time we find explicitly that the right-hand-side of the equation only depends on the unperturbed coordinates1. In other words, we can integrate the time delay along a straight line as defined in Eq. (8), and so the total phase integrated over a travel distance L is given by

 

equation M2310

In static gravity fields, the phase shift doubles if the light is sent back since not only the direction of integration changes, but also the sign of the expression substituted for dt/dλ.

 

Gravity induced ground motion As we will learn in Section 3, seismic fields produce gravity perturbations either through density fluctuations of the ground, or by displacing interfaces between two materials of different density. It is also well-known in seismology that seismic fields can be affected significantly by self-gravity. Self-gravity means that the gravity perturbation produced by a seismic field acts back on the seismic field. The effect is most significant at low frequency where gravity induced acceleration competes against acceleration from elastic forces. In seismology, low-frequency seismic fields are best described in terms of Earth’s normal modes [55]. Normal modes exist as toroidal modes and spheroidal modes. Spheroidal modes are influenced by self-gravity, toroidal modes are not. For example, predictions of frequencies and shapes of spheroidal modes based on Earth models such as PREM (Preliminary Reference Earth Model) [68] are inaccurate if self-gravity effects are excluded. What this practically means is that in addition to displacement amplitudes, gravity becomes a dynamical variable in the elastodynamic equations that determine the normal-mode properties. Therefore, seismic displacement and gravity perturbation cannot be separated in normal-mode formalism (although self-gravity can be neglected in calculations of spheroidal modes at sufficiently high frequency).

In certain situations, it is necessary or at least more intuitive to separate gravity from seismic fields. An exotic example is Earth’s response to GWs [67, 49, 47, 30, 48]. Another example is the seismic response to gravity perturbations produced by strong seismic events at large distance to the source as described in Section 4. It is more challenging to analyze this scenario using normal-mode formalism. The sum over all normal modes excited by the seismic event (each of which describing a global displacement field) must lead to destructive interference of seismic displacement at large distances (where seismic waves have not yet arrived), but not of the gravity amplitudes since gravity is immediately perturbed everywhere. It can be easier to first calculate the gravity perturbation from the seismic perturbation, and then to calculate the response of the seismic field to the gravity perturbation at larger distance. This method will be adopted in this section. Gravity fields will be represented as arbitrary force or tidal fields (detailed models are presented in later sections), and we simply calculate the response of the seismic field. Normal-mode formalism can be avoided only at sufficiently high frequencies where the curvature of Earth does not significantly influence the response (i.e., well above 10 mHz). In this section, we will model the ground as homogeneous half space, but also more complex geologies can in principle be assumed.

 

Gravity can be introduced in two ways into the elastodynamic equations, as a conservative force −∇ψ [146, 169], or as tidal strain The latter method was described first by Dyson to calculate Earth’s response to GWs [67]. The approach also works for Newtonian gravity, with the difference that the tidal field produced by a GW is necessarily a quadrupole field with only two degrees of freedom (polarizations), while tidal fields produced by terrestrial sources are less constrained. Certainly, GWs can only be fully described in the framework of general relativity, which means that their representation as a Newtonian tidal field cannot be used to explain all possible observations [124]. Nonetheless, important here is that Dyson’s method can be extended to Newtonian tidal fields. Without gravity, the elastodynamic equations for small seismic displacement can be written as

 

equation M2411

where equation M25 is the seismic displacement field, and equation M26 is the stress tensor [9]. In the absence of other forces, the stress is determined by the seismic field. In the case of a homogeneous and isotropic medium, the stress tensor for small seismic displacement can be written as

 

equation M2712

The quantity equation M28 is known as seismic strain tensor, and λ, μ are the Lamé constants (see Section 3.1). Its trace is equal to the divergence of the displacement field. Dyson introduced the tidal field from first principles using Lagrangian mechanics, but we can follow a simpler approach. Eq. (12) means that a stress field builds up in response to a seismic strain field, and the divergence of the stress field acts as a force producing seismic displacement. The same happens in response to a tidal field, which we represent as gravity strain equation M29. A strain field changes the distance between two freely falling test masses separated by equation M30 by equation M312. For sufficiently small distances L, the strain field can be substituted by the second time integral of the gravity-gradient tensor equation M32. If the masses are not freely falling, then the strain field acts as an additional force. The corresponding contribution to the material’s stress tensor can be written

 

equation M3313

Since we assume that the gravity field is produced by a distant source, the local contribution to gravity perturbations is neglected, which means that the gravity potential obeys the Laplace equation, equation M34. Calculating the divergence of the stress tensor according to Eq. (11), we find that the gravity term vanishes! This means that a homogeneous and isotropic medium does not respond to gravity strain fields. However, we have to be more careful here. Our goal is to calculate the response of a half-space to gravity strain. Even if the half-space is homogeneous, the Lamé constants change discontinuously across the surface. Hence, at the surface, the divergence of the stress tensor reads

 

equation M3514

In other words, tidal fields produce a force onto an elastic medium via gradients in the shear modulus (second Lamé constant). The gradient of the shear modulus can be written in terms of a Dirac delta function, equation M36, for a flat surface at z = 0 with unit normal vector equation M37. The response to gravity strain fields is obtained applying the boundary condition of vanishing surface traction, equation M38:

 

equation M3915

Once the seismic strain field is calculated, it can be used to obtain the seismic stress, which determines the displacement field equation M40 according to Eq. (11). In this way, one can for example calculate that a seismometer or gravimeter can observe GWs by monitoring surface displacement as was first calculated by Dyson [67].

 

Coupling in non-uniform, static gravity fields If the gravity field is static, but non-uniform, then displacement equation M41 of the test mass in this field due to a non-gravitational fluctuating force is associated with a changing gravity acceleration according to

equation M4216

We introduce a characteristic length λ, over which gravity acceleration varies significantly. Hence, we can rewrite the last equation in terms of the associated test-mass displacement ζ

 

equation M4317

where we have neglected directional dependence and numerical factors. The acceleration change from motion in static, inhomogeneous fields is generally more significant at low frequencies. Let us consider the specific case of a suspended test mass. It responds to fluctuations in horizontal gravity acceleration. The test mass follows the motion of the suspension point in vertical direction (i.e., no seismic isolation), while seismic noise in horizontal direction is suppressed according to Eq. (3). Accordingly, it is possible that the unsuppressed vertical (z-axis) seismic noise ξz(t) coupling into the horizontal (x-axis) motion of the test mass through the term ∂xgz = ∂zgx dominates over the gravity response term in Eq. (2). Due to additional coupling mechanisms between vertical and horizontal motion in real seismic-isolation systems, test masses especially in GW detectors are also isolated in vertical direction, but without achieving the same noise suppression as in horizontal direction. For example, the requirements on vertical test-mass displacement for Advanced LIGO are a factor 1000 less stringent than on the horizontal displacement [22]. Requirements can be set on the vertical isolation by estimating the coupling of vertical motion into horizontal motion, which needs to take the gravity-gradient coupling of Eq. (16) into account. Although, because of the frequency dependence, gravity-gradient effects are more significant in low-frequency detectors, such as the space-borne GW detector LISA [154].

 

Next, we calculate an estimate of gravity gradients in the vicinity of test masses in large-scale GW detectors, and see if the gravity-gradient coupling matters compared to mechanical vertical-to-horizontal coupling.

 

One contribution to gravity gradients will come from the vacuum chamber surrounding the test mass. We approximate the shape of the chamber as a hollow cylinder with open ends (open ends just to simplify the calculation). In our calculation, the test mass can be offset from the cylinder axis and be located at any distance to the cylinder ends (we refer to this coordinate as height). The gravity field can be expressed in terms of elliptic integrals, but the explicit solution is not of concern here. Instead, let us take a look at the results in Figure ​Figure1.1. Gravity gradients ∂zgx vanish if the test mass is located on the symmetry axis or at height L/2. There are also two additional ∂zgx = 0 contour lines starting at the symmetry axis at heights ∼ 0.24 and ∼0.76. Let us assume that the test mass is at height 0.3L, a distance 0.05L from the cylinder axis, the total mass of the cylinder is M = 5000 kg, and the cylinder height is L = 4 m. In this case, the gravity-gradient induced vertical-to-horizontal coupling factor at 20 Hz is

 

equation M4418

This means that gravity-gradient induced coupling is extremely weak, and lies well below estimates of mechanical coupling (of order 0.001 in Advanced LIGO3). Even though the vacuum chamber was modelled with a very simple shape, and additional asymmetries in the mass distribution around the test mass may increase gravity gradients, it still seems very unlikely that the coupling would be significant. As mentioned before, one certainly needs to pay more attention when calculating the coupling at lower frequencies. The best procedure is of course to have a 3D model of the near test-mass infrastructure available and to use it for a precise calculation of the gravity-gradient field.

 

An external file that holds a picture, illustration, etc.

Object name is 41114_2016_3_Fig1.jpg

Figure 1

Gravity gradients inside hollow cylinder. The total height of the cylinder is L, and M is its total mass. The radius of the cylinder is 0.3L. The axes correspond to the distance of the test mass from the symmetry axis of the cylinder, and its height above one of the cylinders ends. The plot on the right is simply a zoom of the left plot into the intermediate heights.

Gravimeters

 

Gravimeters are instruments that measure the displacement of a test mass with respect to a non-inertial reference rigidly connected to the ground. The test mass is typically supported mechanically or magnetically (atom-interferometric gravimeters are an exception), which means that the test-mass response to gravity is altered with respect to a freely falling test mass. We will use Eq. (2) as a simplified response model. There are various possibilities to measure the displacement of a test mass. The most widespread displacement sensors are based on capacitive readout, as for example used in superconducting gravimeters (see Figure ​Figure22 and [96]). Sensitive displacement measurements are in principle also possible with optical readout systems; a method that is (necessarily) implemented in atom-interferometric gravimeters [137], and prototype seismometers [34] (we will explain the distinction between seismometers and gravimeters below). As will become clear in Section 2.4, optical readout is better suited for displacement measurements over long baselines, as required for the most sensitive gravity strain measurements, while the capacitive readout should be designed with the smallest possible distance between the test mass and the non-inertial reference [104].

 

An external file that holds a picture, illustration, etc.

Object name is 41114_2016_3_Fig2.jpg

Figure 2

Sketch of a levitated sphere serving as test mass in a superconducting gravimeter. Dashed lines indicate magnetic field lines. Coils are used for levitation and precise positioning of the sphere. Image reproduced with permission from [96]; copyright by Elsevier.

Let us take a closer look at the basic measurement scheme of a superconducting gravimeter shown in Figure ​Figure2.2. The central part is formed by a spherical superconducting shell that is levitated by superconducting coils. Superconductivity provides stability of the measurement, and also avoids some forms of noise (see [96] for details). In this gravimeter design, the lower coil is responsible mostly to balance the mean gravitational force acting on the sphere, while the upper coil modifies the magnetic gradient such that a certain “spring constant” of the magnetic levitation is realized. In other words, the current in the upper coil determines the resonance frequency in Eq. (2).

 

Capacitor plates are distributed around the sphere. Whenever a force acts on the sphere, the small signal produced in the capacitive readout is used to immediately cancel this force by a feedback coil. In this way, the sphere is kept at a constant location with respect to the external frame. This illustrates a common concept in all gravimeters. The displacement sensors can only respond to relative displacement between a test mass and a surrounding structure. If small gravity fluctuations are to be measured, then it is not sufficient to realize low-noise readout systems, but also vibrations of the surrounding structure forming the reference frame must be as small as possible. In general, as we will further explore in the coming sections, gravity fluctuations are increasingly dominant with decreasing frequency. At about 1 mHz, gravity acceleration associated with fluctuating seismic fields become comparable to seismic acceleration, and also atmospheric gravity noise starts to be significant [53]. At higher frequencies, seismic acceleration is much stronger than typical gravity fluctuations, which means that the gravimeter effectively operates as a seismometer. In summary, at sufficiently low frequencies, the gravimeter senses gravity accelerations of the test mass with respect to a relatively quiet reference, while at higher frequencies, the gravimeter senses seismic accelerations of the reference with respect to a test mass subject to relatively small gravity fluctuations. In superconducting gravimeters, the third important contribution to the response is caused by vertical motion ξ(t) of a levitated sphere against a static gravity gradient (see Section 2.1.4). As explained above, feedback control suppresses relative motion between sphere and gravimeter frame, which causes the sphere to move as if attached to the frame or ground. In the presence of a static gravity gradient ∂zgz, the motion of the sphere against this gradient leads to a change in gravity, which alters the feedback force (and therefore the recorded signal). The full contribution from gravitational, δa(t), and seismic, equation M45, accelerations can therefore be written

 

equation M4619

It is easy to verify, using Eqs. (2) and (3), that the relative amplitude of gravity and seismic fluctuations from the first two terms is independent of the test-mass support. Therefore, vertical seismic displacement of the reference frame must be considered fundamental noise of gravimeters and can only be avoided by choosing a quiet measurement site. Obviously, Eq. (19) is based on a simplified support model. One of the important design goals of the mechanical support is to minimize additional noise due to non-linearities and cross-coupling. As is explained further in Section 2.3, it is also not possible to suppress seismic noise in gravimeters by subtracting the disturbance using data from a collocated seismometer. Doing so inevitably turns the gravimeter into a gravity gradiometer.

 

Gravimeters target signals that typically lie well below 1 mHz. Mechanical or magnetic supports of test masses have resonance frequencies at best slightly below 10 mHz along horizontal directions, and typically above 0.1 Hz in the vertical direction [23, 174]4. Well below resonance frequency, the response function can be approximated as equation M47. At first, it may look as if the gravimeter should not be sensitive to very low-frequency fluctuations since the response becomes very weak. However, the strength of gravity fluctuations also strongly increases with decreasing frequency, which compensates the small response. It is clear though that if the resonance frequency was sufficiently high, then the response would become so weak that the gravity signal would not stand out above other instrumental noise anymore. The test-mass support would be too stiff. The sensitivity of the gravimeter depends on the resonance frequency of the support and the intrinsic instrumental noise. With respect to seismic noise, the stiffness of the support has no influence as explained before (the test mass can also fall freely as in atom interferometers).

 

For superconducting gravimeters of the Global Geodynamics Project (GGP) [52], the median spectra are shown in Figure ​Figure3.3. Between 0.1 mHz and 1 mHz, atmospheric gravity perturbations typically dominate, while instrumental noise is the largest contribution between 1 mHz and 5 mHz [96]. The smallest signal amplitudes that have been measured by integrating long-duration signals is about 10−12 m/s2. A detailed study of noise in superconducting gravimeters over a larger frequency range can be found in [145]. Note that in some cases, it is not fit to categorize seismic and gravity fluctuations as noise and signal. For example, Earth’s spherical normal modes coherently excite seismic and gravity fluctuations, and the individual contributions in Eq. (19) have to be understood only to accurately translate data into normal-mode amplitudes [55].

 

An external file that holds a picture, illustration, etc.

Object name is 41114_2016_3_Fig3.jpg

Figure 3

Median spectra of superconducting gravimeters of the GGP. Image reproduced with permission from [48]; copyright by APS.

Gravity gradiometers

 

It is not the purpose of this section to give a complete overview of the different gradiometer designs. Gradiometers find many practical applications, for example in navigation and resource exploration, often with the goal to measure static or slowly changing gravity gradients, which do not concern us here. For example, we will not discuss rotating gradiometers, and instead focus on gradiometers consisting of stationary test masses. While the former are ideally suited to measure static or slowly changing gravity gradients with high precision especially under noisy conditions, the latter design has advantages when measuring weak tidal fluctuations. In the following, we only refer to the stationary design. A gravity gradiometer measures the relative acceleration between two test masses each responding to fluctuations of the gravity field [102, 125]. The test masses have to be located close to each other so that the approximation in Eq. (4) holds. The proximity of the test masses is used here as the defining property of gradiometers. They are therefore a special type of gravity strainmeter (see Section 2.4), which denotes any type of instrument that measures relative gravitational acceleration (including the even more general concept of measuring space-time strain).

 

Gravity gradiometers can be realized in two versions. First, one can read out the position of two test masses with respect to the same rigid, non-inertial reference. The two channels, each of which can be considered a gravimeter, are subsequently subtracted. This scheme is for example realized in dual-sphere designs of superconducting gravity gradiometers [90] or in atom-interferometric gravity gradiometers [159].

 

It is schematically shown in Figure ​Figure4.4. Let us first consider the dual-sphere design of a superconducting gradiometer. If the reference is perfectly stiff, and if we assume as before that there are no cross-couplings between degrees of freedom and the response is linear, then the subtraction of the two gravity channels cancels all of the seismic noise, leaving only the instrumental noise and the differential gravity signal given by the second line of Eq. (4). Even in real setups, the reduction of seismic noise can be many orders of magnitude since the two spheres are close to each other, and the two readouts pick up (almost) the same seismic noise [125]. This does not mean though that gradiometers are necessarily more sensitive instruments to monitor gravity fields. A large part of the gravity signal (the common-mode part) is subtracted together with the seismic noise, and the challenge is now passed from finding a seismically quiet site to developing an instrument with lowest possible intrinsic noise.

 

An external file that holds a picture, illustration, etc.

Object name is 41114_2016_3_Fig4.jpg

Figure 4

Basic scheme of a gravity gradiometer for measurements along the vertical direction. Two test masses are supported by horizontal cantilevers (superconducting magnets, …). Acceleration of both test masses is measured against the same non-inertial reference frame, which is connected to the ground. Each measurement constitutes one gravimeter. Subtraction of the two channels yields a gravity gradiometer.

The atom-interferometric gradiometer differs in some important details from the superconducting gradiometer. The test masses are realized by ultracold atom clouds, which are (nearly) freely falling provided that magnetic shielding of the atoms is sufficient, and interaction between atoms can be neglected. Interactions of a pair of atom clouds with a laser beam constitute the basic gravity gradiometer scheme. Even though the test masses are freely falling, the readout is not generally immune to seismic noise [80, 18]. The laser beam interacting with the atom clouds originates from a source subject to seismic disturbances, and interacts with optics that require seismic isolation. Schemes have been proposed that could lead to a large reduction of seismic noise [178, 77], but their effectiveness has not been tested in experiments yet. Since the differential position (or tidal) measurement is performed using a laser beam, the natural application of atom-interferometer technology is as gravity strainmeter (as explained before, laser beams are favorable for differential position measurements over long baselines). Nonetheless, the technology is currently insufficiently developed to realize large-baseline experiments, and we can therefore focus on its application in gradiometry. Let us take a closer look at the response of atom-interferometric gradiometers to seismic noise. In atom-interferometric detectors (excluding the new schemes proposed in [178, 77]), one can show that seismic acceleration δα(ω) of the optics or laser source limits the sensitivity of a tidal measurement according to

 

equation M4820

where L is the separation of the two atom clouds, and is the speed of light. It should be emphasized that the seismic noise remains, even if all optics and the laser source are all linked to the same infinitely stiff frame. In addition to this noise term, other coupling mechanisms may play a role, which can however be suppressed by engineering efforts. The noise-reduction factor ωL/c needs to be compared with the common-mode suppression of seismic noise in superconducting gravity gradiometers, which depends on the stiffness of the instrument frame, and on contamination from cross coupling of degrees-of-freedom. While the seismic noise in Eq. (20) is a fundamental noise contribution in (conventional) atom-interferometric gradiometers, the noise suppression in superconducting gradiometers depends more strongly on the engineering effort (at least, we venture to claim that common-mode suppression achieved in current instrument designs is well below what is fundamentally possible).

 

To conclude this section, we discuss in more detail the connection between gravity gradiometers and seismically (actively or passively) isolated gravimeters. As we have explained in Section 2.2, the sensitivity limitation of gravimeters by seismic noise is independent of the mechanical support of the test mass (assuming an ideal, linear support). The main purpose of the mechanical support is to maximize the response of the test mass to gravity fluctuations, and thereby increase the signal with respect to instrumental noise other than seismic noise. Here we will explain that even a seismic isolation of the gravimeter cannot overcome this noise limitation, at least not without fundamentally changing its response to gravity fluctuations. Let us first consider the case of a passively seismically isolated gravimeter. For example, we can imagine that the gravimeter is suspended from the tip of a strong horizontal cantilever. The system can be modelled as two oscillators in a chain, with a light test mass m supported by a heavy mass M representing the gravimeter (reference) frame, which is itself supported from a point rigidly connected to Earth. The two supports are modelled as harmonic oscillators. As before, we neglect cross coupling between degrees of freedom. Linearizing the response of the gravimeter frame and test mass for small accelerations, and further neglecting terms proportional to m/M, one finds the gravimeter response to gravity fluctuations:

 

equation M4921

Here, ω1, γ1 are the resonance frequency and damping of the gravimeter support, while ω2, γ2 are the resonance frequency and damping of the test-mass support. The response and isolation functions R(·), S(·) are defined in Eqs. (2) and (3). Remember that Eq. (21) is obtained as a differential measurement of test-mass acceleration versus acceleration of the reference frame. Therefore, δg1(ω) denotes the gravity fluctuation at the center-of-mass of the gravimeter frame, and δg2(ω) at the test mass. An infinitely stiff gravimeter suspension, ω1 → ∞, yields R(ω; ω1, γ1) = 0, and the response turns into the form of the non-isolated gravimeter. The seismic isolation is determined by

 

equation M5022

We can summarize the last two equations as follows. At frequencies well above ω1, the seismically isolated gravimeter responds like a gravity gradiometer, and seismic noise is strongly suppressed. The deviation from the pure gradiometer response ∼ δg2(ω) − δg1(ω) is determined by the same function S(ω; ω1, γ1) that describes the seismic isolation. In other words, if the gravity gradient was negligible, then we ended up with the conventional gravimeter response, with signals suppressed by the seismic isolation function. Well below ω1, the seismically isolated gravimeter responds like a conventional gravimeter without seismic-noise reduction. If the centers of the masses m (test mass) and M (reference frame) coincide, and therefore δg1(ω) = δg2(ω), then the response is again like a conventional gravimeter, but this time suppressed by the isolation function S(ω; ω1, γ1).

 

Let us compare the passively isolated gravimeter with an actively isolated gravimeter. In active isolation, the idea is to place the gravimeter on a stiff platform whose orientation can be controlled by actuators. Without actuation, the platform simply follows local surface motion. There are two ways to realize an active isolation. One way is to place a seismometer next to the platform onto the ground, and use its data to subtract ground motion from the platform. The actuators cancel the seismic forces. This scheme is called feed-forward noise cancellation. Feed-forward cancellation of gravity noise is discussed at length in Section 7.1, which provides details on its implementation and limitations. The second possibility is to place the seismometer together with the gravimeter onto the platform, and to suppress seismic noise in a feedback configuration [4, 2]. In the following, we discuss the feed-forward technique as an example since it is easier to analyze (for example, feedback control can be unstable [4]). As before, we focus on gravity and seismic fluctuations. The seismometer’s intrinsic noise plays an important role in active isolation limiting its performance, but we are only interested in the modification of the gravimeter’s response. Since there is no fundamental difference in how a seismometer and a gravimeter respond to seismic and gravity fluctuations, we know from Section 2.2 that the seismometer output is proportional to δg1(ω) − δα(ω), i.e., using a single test mass for acceleration measurements, seismic and gravity perturbations contribute in the same way. A transfer function needs to be multiplied to the acceleration signals, which accounts for the mechanical support and possibly also electronic circuits involved in the seismometer readout. To cancel the seismic noise of the platform that carries the gravimeter, the effect of all transfer functions needs to be reversed by a matched feed-forward filter. The output of the filter is then equal to δg1(ω) − δα(ω) and is added to the motion of the platform using actuators cancelling the seismic noise and adding the seismometer’s gravity signal. In this case, the seismometer’s gravity signal takes the place of the seismic noise in Eq. (3). The complete gravity response of the actively isolated gravimeter then reads

 

equation M5123

The response is identical to a gravity gradiometer, where ω2, γ2 are the resonance frequency and damping of the gravimeter’s test-mass support. In reality, instrumental noise of the seismometer will limit the isolation performance and introduce additional noise into Eq. (23). Nonetheless, Eqs. (21) and (23) show that any form of seismic isolation turns a gravimeter into a gravity gradiometer at frequencies where seismic isolation is effective. For the passive seismic isolation, this means that the gravimeter responds like a gradiometer at frequencies well above the resonance frequency ω1 of the gravimeter support, while it behaves like a conventional gravimeter below ω1. From these results it is clear that the design of seismic isolations and the gravity response can in general not be treated independently. As we will see in Section 2.4 though, tidal measurements can profit strongly from seismic isolation especially when common-mode suppression of seismic noise like in gradiometers is insufficient or completely absent.

 

Gravity strainmeters

 

Gravity strain is an unusual concept in gravimetry that stems from our modern understanding of gravity in the framework of general relativity. From an observational point of view, it is not much different from elastic strain. Fluctuating gravity strain causes a change in distance between two freely falling test masses, while seismic or elastic strain causes a change in distance between two test masses bolted to an elastic medium. It should be emphasized though that we cannot always use this analogy to understand observations of gravity strain [106]. Fundamentally, gravity strain corresponds to a perturbation of the metric that determines the geometrical properties of spacetime [124]. We will briefly discuss GWs, before returning to a Newtonian description of gravity strain.

 

Gravitational waves are weak perturbations of spacetime propagating at the speed of light. Freely falling test masses change their distance in the field of a GW. When the length of the GW is much larger than the separation between the test masses, it is possible to interpret this change as if caused by a Newtonian force. We call this the long-wavelength regime. Since we are interested in the low-frequency response of gravity strainmeters throughout this article (i.e., frequencies well below 100 Hz), this condition is always fulfilled for Earth-bound experiments. The effect of a gravity-strain field equation M52 on a pair of test masses can then be represented as an equivalent Newtonian tidal field

 

equation M5324

Here, equation M54 is the relative acceleration between two freely falling test masses, L is the distance between them, and equation M55 is the unit vector pointing from one to the other test mass, and equation M56 its transpose. As can be seen, the gravity-strain field is represented by a 3 × 3 tensor. It contains the space-components of a 4-dimensional metric perturbation of spacetime, and determines all properties of GWs5. Note that the strain amplitude h in Eq. (24) needs to be multiplied by 2 to obtain the corresponding amplitude of the metric perturbation (e.g., the GW amplitude). Throughout this article, we define gravity strain as h = ΔL/L, while the effect of a GW with amplitude aGW on the separation of two test mass is determined by aGW = 2ΔL/L.

 

The strain field of a GW takes the form of a quadrupole oscillation with two possible polarizations commonly denoted × (cross)-polarization and +(plus)-polarization. The arrows in Figure ​Figure55 indicate the lines of the equivalent tidal field of Eq. (24).

 

An external file that holds a picture, illustration, etc.

Object name is 41114_2016_3_Fig5.jpg

Figure 5

Polarizations of a gravitational wave.

Consequently, to (directly) observe GWs, one can follow two possible schemes: (1) the conventional method, which is a measurement of the relative displacement of suspended test masses typically carried out along two perpendicular baselines (arms); and (2) measurement of the relative rotation between two suspended bars. Figure ​Figure66 illustrates the two cases. In either case, the response of a gravity strainmeter is obtained by projecting the gravity strain tensor onto a combination of two unit vectors, equation M57 and equation M58, that characterize the orientation of the detector, such as the directions of two bars in a rotational gravity strain meter, or of two arms of a conventional gravity strain meter. This requires us to define two different gravity strain projections. The projection for the rotational strain measurement is given by

 

equation M5925

where the subscript × indicates that the detector responds to the ×-polarization assuming that the x, y-axes (see Figure ​Figure5)5) are oriented along two perpendicular bars. The vectors equation M60 and equation M61 are rotated counter-clockwise by 90° with respect to equation M62 and equation M63. In the case of perpendicular bars equation M64 and equation M65. The corresponding projection for the conventional gravity strain meter reads

 

equation M6626

The subscript + indicates that the detector responds to the +-polarization provided that the x, y-axes are oriented along two perpendicular baselines (arms) of the detector. The two schemes are shown in Figure ​Figure6.6. The most sensitive GW detectors are based on the conventional method, and distance between test masses is measured by means of laser interferometry. The LIGO and Virgo detectors have achieved strain sensitivities of better than 10−22 Hz−1/2 between about 50 Hz and 1000 Hz in past science runs and are currently being commissioned in their advanced configurations [91, 7]. The rotational scheme is realized in torsion-bar antennas, which are considered as possible technology for sub-Hz GW detection [155, 69]. However, with achieved strain sensitivity of about 10−8 Hz−1/2 near 0.1 Hz, the torsion-bar detectors are far from the sensitivity we expect to be necessary for GW detection [88].

 

An external file that holds a picture, illustration, etc.

Object name is 41114_2016_3_Fig6.jpg

Figure 6

Sketches of the relative rotational and displacement measurement schemes.

Let us now return to the discussion of the previous sections on the role of seismic isolation and its impact on gravity response. Gravity strainmeters profit from seismic isolation more than gravimeters or gravity gradiometers. We have shown in Section 2.2 that seismically isolated gravimeters are effectively gravity gradiometers. So in this case, seismic isolation changes the response of the instrument in a fundamental way, and it does not make sense to talk of seismically isolated gravimeters. Seismic isolation could in principle be beneficial for gravity gradiometers (i.e., the acceleration of two test masses is measured with respect to a common rigid, seismically isolated reference frame), but the common-mode rejection of seismic noise (and gravity signals) due to the differential readout is typically so high that other instrumental noise becomes dominant. So it is possible that some gradiometers would profit from seismic isolation, but it is not generally true. Let us now consider the case of a gravity strainmeter. As explained in Section 2.3, we distinguish gradiometers and strainmeters by the distance of their test masses. For example, the distance of the LIGO or Virgo test masses is 4 km and 3 km respectively. Seismic noise and terrestrial gravity fluctuations are insignificantly correlated between the two test masses within the detectors’ most sensitive frequency band (above 10 Hz). Therefore, the approximation in Eq. (4) does not apply. Certainly, the distinction between gravity gradiometers and strainmeters remains somewhat arbitrary since at any frequency the approximation in Eq. (4) can hold for one type of gravity fluctuation, while it does not hold for another. Let us adopt a more practical definition at this point. Whenever the design of the instrument places the test masses as distant as possible from each other given current technology, then we call such an instrument strainmeter. In the following, we will discuss seismic isolation and gravity response for three strainmeter designs, the laser-interferometric, atom-interferometric, and superconducting strainmeters. It should be emphasized that the atom-interferometric and superconducting concepts are still in the beginning of their development and have not been realized yet with scientifically interesting sensitivities.

 

Laser-interferometric strainmeters The most sensitive gravity strainmeters, namely the large-scale GW detectors, use laser interferometry to read out the relative displacement between mirror pairs forming the test masses. Each test mass in these detectors is suspended from a seismically isolated platform, with the suspension itself providing additional seismic isolation. Section 2.1.1 introduced a simplified response and isolation model based on a harmonic oscillator characterized by a resonance frequency ω0 and viscous damping γ6. In a multi-stage isolation and suspension system as realized in GW detectors (see for example [37, 121]), coupling between multiple oscillators cannot be neglected, and is fundamental to the seismic isolation performance, but the basic features can still be explained with the simplified isolation and response model of Eqs. (2) and (3). The signal output of the interferometer is proportional to the relative displacement between test masses. Since seismic noise is approximately uncorrelated between two distant test masses, the differential measurement itself cannot reject seismic noise as in gravity gradiometers. Without seismic isolation, the dominant signal would be seismic strain, i.e., the distance change between test masses due to elastic deformation of the ground, with a value of about 10−15 Hz−1/2 at 50 Hz (assuming kilometer-scale arm lengths). At the same time, without seismically isolated test masses, the gravity signal can only come from the ground response to gravity fluctuations as described in Section 2.1.3, and from the Shapiro time delay as described in Section 2.1.2.

 

www.ncbi.nlm.nih.gov/pmc/articles/PMC5256008/

The cylinder in the middle has a sheet of 35 mm film attached to it's inside perimeter. A light bulb in the vertical tower illuminated the film and projects it inside the triangular box. I suspect there is a mirror in there. The mirror would then project the image on the front 'screen'. Notice the big spring below the drum? Changing bands compresses the spring and advances to one of 3 levels on the film to display the proper frequency and country notation. I'd like to see this one work someday. The chassis is a mess. The oscillator coil is incorrect. I have 2 other coils that are correct but appear to be open. Oh well. It is cool!

The scope has an input channel not working. Signal generator just needs cleaned up and a dial part replaces. Hard to beat hp test gear of any vintage. The BK is ok but not Tektronix. I’ll be using my Tek scopes to fix it. Probably sell it.

Audion oscillators are replacing radio-frequency alternators for radio transmission...

 

The Outline of Radio, by John V. L. Hogan. Boston: Little, Brown, 1923.

From the Future Ventures’ 🚀 Space Collection. Photos by technoarchaeologist Curious Marc, who is getting my heroic Apollo artifacts working again! Stay tuned, so to speak.

 

This unit takes the phase-modulated signal and FM TV signal, combines them, modulates them, and amplifies them before sending them to the main amplifier. It also has the receiver circuitry. It also has interesting ranging circuitry: NASA sent a pseudo-random ranging sequence to the spacecraft and this box amplified and returned the signal. On the ground, they measured how long the signal took (by correlating the returned signal with the sent signal), which gave them an accurate distance to the spacecraft. Since this box includes amplification, it can be used without the main amplifier, and they could do that on Apollo if the main amplifier failed.

 

From Spaceaholic: "Apollo Command Module Unified S-Band Transponder (manufactured by Motorola, Inc., Military Electronics Division, Scottsdale, Ariz.). The Unified S-Band Transponder was the only method of exchanging voice communications, tracking, biomedical, and ranging, transmission of pulse code modulated (PCM) data and television, and reception of uplinked data from Mission Control once the Apollo Command Module was outside a range of 1500 nautical miles and line of sight from Manned Space Flight Network (MSFN) ground stations strung around the Earth (within that range, VHF was available). The term "Unified" is applicable because the communications system combined the functions of (signal) acquisition, telemetry, command, voice, television and tracking on one radio link. This design resulted in fewer antennas/electronics assemblies (and thus decreased complexity and weight) on both the spacecraft and the ground station segments of the MSFN. The Unified S-Band Equipment (USBE) onboard the Apollo Command Module, Lunar Module, Lunar Rover were absolutely critical to the successful execution of the Apollo program; and reliability was assured through the implementation of full redundant, heavily tested design.

 

The Electronic assembly hosts a redundant architecture consisting of two phase-locked transponders and one frequency modulated transmitter housed in single, gasket-sealed, machined aluminum case, 9.5 by 6 by 21 inches. The unit weighs 32 pounds, operated from 400 Hertz power, with RF output of 300 milliwatts, with a fixed transmit frequency of 2287.5 Megahertz (MHZ) / receive frequency 2106.4 MHZ.

 

The S-band transponder is a double-superheterodyne phase-lock loop receiver that accepted a phase-modulated radio frequency signal containing the updata and up-voice subcarriers, and a pseudo-random noise code when ranging was desired. This signal is supplied to the receiver via the triplexer integral to the S-band power amplifier equipment and presented to three separate detectors: the narrow- band loop phase detector, the narrow-band coherent amplitude detector, and the wide-band phase detector. In the wide-band phase detector, the intermediate frequency is detected, and the 70-kiloHertz up-data and kilohertz up-voice subcarriers are extracted, amplified, and routed to the up-data and up-voice discriminators in the premodulation processor.

 

When operating in a ranging mode, the pseudo-random noise ranging signal is detected, filtered, and routed to the S-band transmitter as a signal input to the phase modulator. In the loop- phase detector, the intermediate frequency signal is filtered and detected by comparing it with the loop reference frequency. The resulting dc output is used to control the frequency of the voltage-controlled oscillator. The output of the voltage controlled oscillator is used as the reference frequency for receiver circuits as well as for the transmitter. The coherent amplitude detector provided the automatic gain control for receiver sensitivity control. In addition, it detected the amplitude modulation of the carrier introduced by the high-gain antenna system. This detected output was returned to the antenna control system to point the high- gain antenna to the ground station. When the antenna pointed at the ground station, the amplitude modulation was minimized. An additional function of the detector was to select the auxiliary oscillator to provide a stable carrier for the transmitter, whenever the receiver lost lock. The S-band transponders could transmit a phase- modulated signal with the initial transmitter frequency obtained from one of two sources: the voltage controlled oscillator in the phase-locked disband receiver or the auxiliary oscillator in the transmitter. Selection of the excitation was controlled by a coherent amplitude detector.

 

The S-band equipment also contains a separate FM transmitter which permitted scientific, television, or playback data to be sent simultaneously to the ground while voice, real-time data, and ranging were being sent via the transponder."

Episodes from the History of Electricity.

 

If you like it, please support it at Ideas! Thank you!

 

Benjamin Franklin (1750 - Lightning is electrical)

 

Franklin was a leading author, printer, political theorist, politician (was one of the Founding Fathers of the United States), postmaster, scientist, inventor, civic activist, statesman, and diplomat. As a scientist, he was a major figure in the American Enlightenment and the history of physics for his discoveries and theories regarding electricity. As an inventor, he is known for the lightning rod, bifocals, and the Franklin stove, among other inventions.

 

In 1750 he published a proposal for an experiment to prove that lightning is electricity by flying a kite in a storm that appeared capable of becoming a lightning storm. On May 10, 1752, Thomas-François Dalibard of France conducted Franklin's experiment using a 40-foot-tall (12 m) iron rod instead of a kite, and he extracted electrical sparks from a cloud. On June 15 Franklin may possibly have conducted his well known kite experiment in Philadelphia, successfully extracting sparks from a cloud.

 

Franklin's electrical experiments led to his invention of the lightning rod.

  

Luigi Aloisio Galvani (1781 - "Animal Electricity")

 

Galvani was an Italian physician, physicist and philosopher who lived in Bologna.

 

With his experiment he discovered that the body of animals is powered by electrical impulses. Galvani named this newly discovered force “animal electricity,” and thus laid foundations for the modern fields of electrophysiology and neuroscience.

 

Galvani’s contemporaries - including Benjamin Franklin, whose work helped prove the existence of atmospheric electricity - had made great strides in understanding the nature of electricity and how to produce it. Inspired by Galvani’s discoveries, fellow Italian scientist Alessandro Volta would go on to invent, in 1800, the first electrical battery - the voltaic pile - which consisted of brine-soaked pieces of cardboard or cloth sandwiched between disks of different metals.

  

Thomas Alva Edison (1882 - First Power Station)

 

Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. Dubbed "The Wizard of Menlo Park", he was one of the first inventors to apply the principles of mass production and large-scale teamwork to the process of invention, and because of that, he is often credited with the creation of the first industrial research laboratory.

 

In 1878, Edison formed the Edison Electric Light Company (today as General Electric) in New York City with several financiers, including J. P. Morgan and the members of the Vanderbilt family. Edison made the first public demonstration of his incandescent light bulb on December 31, 1879, in Menlo Park. It was during this time that he said: "We will make electricity so cheap that only the rich will burn candles."

 

After devising a commercially viable electric light bulb on October 21, 1879, Edison patented a system for electricity distribution in 1880, which was essential to capitalize on the invention of the electric lamp.

The company established the first investor-owned electric utility in 1882 on Pearl Street Station, New York City. It was on September 4, 1882, that Edison switched on his Pearl Street generating station's electrical power distribution system, which provided 110 volts direct current (DC) to 59 customers in lower Manhattan. Earlier in the year, in January 1882, he had switched on the first steam-generating power station at Holborn Viaduct in London. The DC supply system provided electricity supplies to street lamps and several private dwellings within a short distance of the station.

 

Edison was a prolific inventor, holding 1,093 US patents in his name. More significant than the number of Edison's patents was the widespread impact of his inventions: electric light and power utilities, sound recording, and motion pictures all established major new industries world-wide. Edison's inventions contributed to mass communication and, in particular, telecommunications. These included a stock ticker, a mechanical vote recorder, a battery for an electric car, electrical power, recorded music and motion pictures.

  

Nicola Tesla (1891 - Tesla Coil)

 

Tesla was a Serbian American inventor, electrical engineer, mechanical engineer, and futurist best known for his contributions to the design of the modern alternating current (AC) electricity supply system.

 

Tesla moved to New York in 1884 and introduced himself to Thomas Edison. Although Tesla and Edison shared a mutual respect for one another, at least at first, Tesla challenged Edison’s claim that current could only flow in one direction (DC, direct current). Tesla claimed that energy was cyclic and could change direction (AC, alternating current), which would increase voltage levels across greater distances than Edison had pioneered. In 1888, Tesla went to work for Westinghouse in order to develop the alternating current system. Westinghouse and Tesla in their design for the first hydroelectric power plant in Niagara Falls.

 

Around 1891 Tesla invented the Tesla coil, which is an electrical resonant transformer circuit. It is used to produce high-voltage, low-current, high frequency alternating-current electricity. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits. In 1899 Tesla moved to Colorado Springs, where he would have room for his high-voltage, high-frequency experiments: Tesla was sitting in his laboratory with his "Magnifying transmitter" generating millions of volts.

 

Tesla invented the first alternating current (AC) motor and developed AC generation and transmission technology, invented electric oscillators, meters, improved lights. He also experimented with X-rays and gave short-range demonstrations of radio communication.

 

A double-well oscillator falling into a trap

More Computer History Photos here!

 

The Zenith Z-19 serial terminal is equivalent to the Heathkit H-19 terminal. This is a dumb terminal. It has no local processing functions. It communicates with a minicomputer or mainframe over an RS-232 serial interface. For remote operation, this was often used with a modem. This is late 1970s, early 1980s technology. The monochrome green screen is standard 24 lines x 80 columns, text only, upper/lower case.

 

Nearby is the TECO editor reference card, and a PDP-8/i reference card.

 

The classic source code on screen is from www.pdp12.org/ (no affiliation).

 

This was around $600 new. When I bought this, the serial port didn't work. When I called Zenith, they said I was entitled to on-site support! They sent someone out from the nearest office, about 60 miles away. He almost didn't believe my problem was real, since it worked fine with a loopback jumper. He found that the baud-rate oscillator was running at the wrong speed. The motherboard was replaced, and it was good to go.

 

This photo has received quite a few views from various blogs. This photo is on Creative Commons license, and this is how it's supposed to work. I'm encouraged by this sort of behavior to allow more of my stuff to be used on Creative Commons license.

 

If you're visiting from a blog, welcome, and I appreciate Flickr comments. If you like this photo, you may want to have a look at my other old computer photos in my Computer History set (Link on the right).

Please take a look at my photostream for the latest!

In Sufi Time, Ether-Ruach was very well known as well, and this is the essence of Sufi's architecture and construction. Indeed, Koutoubia is nothing else then pyramid in miniature, where the main purpose is to grasp as much as is possible of the Ether-Ruach energy that is permanently permeating our planet and providing life-supporting influences. Thus, such a minaret would grasp that precious life supporting cosmic energy, and will transfer it to homeowners for their wellbeing, and for the fast enlightenment of theirs. This function is being achieved through energy transfer between metallic bulbs on the top of the roof, and the oscillator , which functions as a freeway. Hence, the omnipresent Ether-Ruach will induce a stream of negative ions coming out from the metal parts of bulbs, which will be then transferred through the freeway of Sufi , and further on throughout the entire mosque. Therefore, for that purpose, Kalash on top of the roof should inevitably be of metallic background. The golden plated bulbs were predominantly used, because of the stability of gold to radiate negative ions on a long-term basis. Today, golden, or golden plated bulbs, is easy to be replaced with one of brass or some similar material

The balloon itself would have been wrapped with the foil, that was the active metallic material, and the very important element.. needed for his devices. It served as an input terminal to his much complex device actually. That was using this device for taping the radiant energy, the Ether-Ruach, from the space around. It is all very complex actually, so I do not want to go deeper into this topic. Just to say that the device could have supplied the energy for heaters to heat homes, for energy's bulbs.

 

There is an interesting story that just recently has come to me. It is about Koutoubia, who, when searching the proper place for his hermitage, saw similar light pillars at the certain spot, what he understood as a divine sign to be settled at that spot exactly. He made well because exactly such omens indicate there is plenty of Ether-Ruach around, and the story has it that he was enlightened very soon afterward.First of all, it is important to know that the Kutubiah is not built by chance at this place: indeed, there are flows of the 7 metals that criss-cross the Earth like meridians. The Kutubiah is at the crossroads of two simple gold streams, one North-South passing through Santiago, Tomar and Marrakesh. An east-west flow passes through Damascus, Gardaïa and Marrakesh. The tower is therefore a scalar wave sensor. The rest is a parallel with experiments carried out in Ireland on identical towers and in India. The metal balls are like tachyon energy sensors or organ cannons.

 

Koutoubia architecture with domes and minarets that were made of materials with equivalent properties, and the domes and tops of minarets were covered with silver, gold, and copper tin, just like obelisks.

Such a use of natural energetics has been known for ages, with one basic purpose: accumulating vital life energies, which was used for the greater good, for the mind and the body of every person who entered such an object.

Measurements demonstrate that sacral objects were mostly constructed in places with earthly telluric radiation, and made of paramagnetic materials that attract the magnetic and electric fields of the Sun and the stars. Recent measurements have determined that the voltage difference between the Earth and the ionosphere is 400.000 volts, which is displayed . To build their massive structures, ancient architects were mainly using basalt, limestone, sandstone and marble.

It is obvious that they cared about the crystal contents of their construction material, probably because of their specific properties which they acknowledged and abundantly used. Crystals can be induced to oscillate and brought into resonance with electric energy, termically, with pressure, sound, and by other means.

 

The minaret is designed in almohad style and was constructed of sandstone. It was originally covered with Marrakshi pink plaster, but in the 1990s, experts opted to expose the original stone work and removed the plaster. The minaret tower is 77 metres (253 ft) in height, including the spire, itself 8 metres (26 ft) tall. Each side of the square base is 12.8 metres (42 ft) in length. The minaret is visible from a distance of 29 kilometres (18 mi). Its prominence makes it a landmark structure of Marrakesh, which is maintained by an ordinance prohibiting any high rise buildings (above the height of a palm tree) to be built around it. The muezzin calling the faithful for the adhan (prayer), is given from the four cardinal directions at the top of the minaret.Its design includes a high angular shaft with a smaller but identical superstructure resting on it, topped by a dome. Many features of the minaret are also included in other religious buildings in the country, such as a wide band of ceramic tiles, alternate pattern work on each side, and Moorish-styled scalloped keystone arches . Decorative carvings envelop the arched fenestrations. Above four-fifths of its height, the minaret has stepped merlons capping the perimeter of the shaft, at which level there is an outdoor gallery approached by ramps. Each side of the tower is designed differently as the window openings are arranged at different heights, conforming to the ascending ramp inside the minaret.The minaret is topped by a spire. The spire includes gilded copper balls, decreasing in size towards the top, a traditional style of Morocco.[11] There are multiple legends about the orbs. One such legend states that the globes were originally made of pure gold, and there were at one time only three of them, the fourth having been donated by the wife of Yaqub al-Mansur as penance for breaking her fast for three hours one day during Ramzān. She had her golden jewelry melted down to form the fourth globe.Another version of the legend is that the balls were originally made entirely of gold fashioned from the jewellery of the wife of Saadian Sultan Ahmad al-Mansur. There is a flag pole next to the copper balls forming the spire, which is used for hoisting the religious green flag of the Prophet, which the muezzin does every Friday and on religious occasions. The floodlit tower has pleasant views at night.

The Koutoubia Mosque or Kutubiyya Mosque (Arabic: جامع الكتبية‎‎ Arabic pronunciation: [jaːmiʕu‿lkutubijːa(h)]) is the largest mosque in Marrakesh, Morocco. The mosque is also known by several other names, such as Jami' al-Kutubiyah, Kotoubia Mosque, Kutubiya Mosque, Kutubiyyin Mosque, and Mosque of the Booksellers. It is located in the southwest medina quarter of Marrakesh.The mosque is ornamented with curved windows, a band of ceramic inlay, pointed merlons, and decorative arches; it has a large plaza with gardens, and is floodlit at night. The minaret, 77 metres (253 ft) in height, includes a spire and orbs. It was completed under the reign of the Berber Almohad Caliph Yaqub al-Mansur (1184 to 1199), and has inspired other buildings such as the Giralda of Seville and the Hassan Tower of Rabat.The minaret plan and design remained the same in both buildings.While in the first mosque, the orientation of the mihrab was 5 degrees out of alignment with respect to the direction towards Mecca, in the second mosque, the orientation was 10 degrees off, thus actually further out of alignment with Mecca than the first mosque.

Both these structures were built during the rule of Abd al-Mu'min (reign 1130–63). The second mosque was started after 1154 and the building was partially completed by September 1158, with the first prayers held in the mosque at that time. It was completed by the 1190s, though reported completion dates vary between 1162, 1190 and 1199. The first mosque eventually deteriorated. It is apparent that the second mosque was not built as an alternative to the first one, as the two mosques shared the same site for 30 years before the first mosque became derelict.en.wikipedia.org/wiki/Koutoubia_Mosque

Part of Dr Grordbort's Infallible Aether Oscillators collection, made by Weta. They're unbelievably detailed and beautifully made.

Generative drawing with particles, attractors, repelers and oscillators.

A period-7 orbit of an electronic double-well oscillator. Phase plane portrait.

I was delighted to get Serial Number 69... Seems appropriate when you get your Freak on.

 

The watch mechanism and is built into the minute hand that drives a gear around the toothed rim.

This model, with only 75 made, is the first automatic double oscillator with a differential, which draws the average of their rates. This required lightweight silicon MEMS gears coated with synthetic diamond for abrasion resistance.

 

Here is a cool video of it in action, and dedicated website.

 

The face is black aventurine glass with flecks of copper. The body is titanium, ceramic and gold.

 

“The Freak is one of the ten watches that have revolutionized watchmaking over the course of the last twenty years” — The New York Times.

Nikon F-501/N2020

Integral-motor autofocus 35mm single lens reflex.

 

Picture Format 24 x 36mm DX coded 35mm (135) film format

 

Dual autofocus modes (Single servo and Continuous servo) focus assist and manual focusing.

 

Autofocus Lock Single Servo AF

 

Focus Assist Available in manual focus mode with an AF Nikkor, Nikkor or Series E lens with a maximum aperture of f:4.5 or faster

 

Exposure Metering Light intensity feedback measurement (for P DUAL, P HI and A), TTL full aperture centerweighted measurement (for manual exposure) employs one silicone photo diode (SPD).

 

Metering Range (at ISO 100 with f/1.4 lens) EV 1 to EV19

 

Exposure Modes Three Programs (dual, normal and high speed) auto exposure modes, Auto, Aperture-Priority Auto and Manual

 

Shutter Electromagnetically controlled vertical-travel focal-plane shutter

 

Electromagnetic shutter Release.

 

Shutter Speeds Stepless from 1/2000 to 1 sec. in P DUAL, P, P HI and A auto exposure modes. Lithium niobate oscillator-controlled speeds from 1/2000 to 1 sec on manual; electromagnetically controlled Bulb setting is provided

 

Viewfinder Fixed eyelevel pentaprism high-eyepoint type; 0.85X magnification with 50mm lens set at infinity; approx. 92% frame coverage

 

Focusing Screen Nikon type B clear matte with central focus brackets, 12 mm circle denotes centre weighted metering area; changeable with type E or J focusing screens.

 

Film Speed Range ISO 25 to 5000 for DX-coded film; ISO 12 to 3200 can be manually set for non-DX coded film.

 

Motorised film advance, with automatic film loading and rewind

 

Frame Counter Additive type; counts back while film is being rewound

 

Self-timer Electronically controlled 10 sec. delay.

 

Reflex Mirror Automatic, instant-return type

 

Data Back MF-19.

  

Flash Synchronization Up to 1/125 sec.

 

Power source: Nikon AA battery holder MB-3, f4 1.5V AA batteries

 

Dimensions (W x H x D) 15 x 10 x 5 cm.

 

Weight (without batteries) Approx. 600g

 

I invite you to visit my camera site at Classic Cameras in english.

Convido-os a visitar o minha página Câmaras & Cia. em português

Nikola Tesla (1856 – 1943) was a Serbian American inventor, electrical engineer, mechanical engineer, physicist, and futurist best known for his contributions to the design of the modern alternating current (AC) electricity supply system.

 

Tesla gained experience in telephony and electrical engineering before immigrating to the United States in 1884 to work for Thomas Edison in New York City. He soon struck out on his own with financial backers, setting up laboratories and companies to develop a range of electrical devices. His patented AC induction motor and transformer were licensed by George Westinghouse, who also hired Tesla for a short time as a consultant. His work in the formative years of electric power development was involved in a corporate alternating current/direct current "War of Currents" as well as various patent battles.

 

Tesla went on to pursue his ideas of wireless lighting and electricity distribution in his high-voltage, high-frequency power experiments in New York and Colorado Springs, and made early (1893) pronouncements on the possibility of wireless communication with his devices. He tried to put these ideas to practical use in his ill-fated attempt at intercontinental wireless transmission, which was his unfinished Wardenclyffe Tower project. In his lab he also conducted a range of experiments with mechanical oscillators/generators, electrical discharge tubes, and early X-ray imaging. He also built a wireless controlled boat, one of the first ever exhibited.

 

Tesla was renowned for his achievements and showmanship, eventually earning him a reputation in popular culture as an archetypal "mad scientist". His patents earned him a considerable amount of money, much of which was used to finance his own projects with varying degrees of success. He lived most of his life in a series of New York hotels, through his retirement. He died on 7 January 1943. His work fell into relative obscurity after his death, but in 1960 the General Conference on Weights and Measures named the SI unit of magnetic flux density the tesla in his honor. Tesla has experienced a resurgence in interest in popular culture since the 1990s. [Source: Wikipedia]

 

The balance wheel keeps time for the watch. It consists of a weighted wheel which rotates back and forth, which is returned toward its center position by a fine spiral spring, the balance spring or "hair spring". The wheel and spring together constitute a harmonic oscillator. The mass of the balance wheel combines with the stiffness of the spring to precisely control the period of each swing or 'beat' of the wheel.

Marco Bischof's widely acclaimed book has already sold some 30'000 German-language copies (9th printing) since its publication in March 1995, and the success is continuing. It is the first comprehensive book on the world market for the general and scientific public on one of the hottest fields of frontier science which is about to lead to major conceptual breakthroughs and many useful applications in biophysics, biomedical science, biology, biotechnology, environmental science and food technology. Thousands of medical doctors, scientists, and interested laypersons in Germany, Switzerland and Austria who from the many newspaper and magazine articles and from several TV features in the last couple of years were aware of this development of potential breakthroughs in a number of scientific disciplines and wanted to obtain more precise and broadly accessible information have been waiting for this book that will remain the definitive publication on the topic for many years to come. Russian and Chinese translations are in preparation. The book has been awarded the 1995 Book Price by the Scientific and Medical Network (U.K.) and the Swiss Award 1997 by the Swiss Parapsychological Foundation.

What are biophotons ?

Biophotons, or ultraweak photon emissions of biological systems, are weak electromagnetic waves in the optical range of the spectrum - in other words: light. All living cells of plants, animals and human beings emit biophotons which cannot be seen by the naked eye but can be measured by special equipment developed by German researchers.

This light emission is an expression of the functional state of the living organism and its measurement therefore can be used to assess this state. Cancer cells and healthy cells of the same type, for instance, can be discriminated by typical differences in biophoton emission. After an initial decade and a half of basic research on this discovery, biophysicists of various European and Asian countries are now exploring the many interesting applications which range across such diverse fields as cancer research, non-invasive early medical diagnosis, food and water quality testing, chemical and electromagnetic contamination testing, cell communication, and various applications in biotechnology.

 

According to the biophoton theory developed on the base of these discoveries the biophoton light is stored in the cells of the organism - more precisely, in the DNA molecules of their nuclei - and a dynamic web of light constantly released and absorbed by the DNA may connect cell organelles, cells, tissues, and organs within the body and serve as the organism's main communication network and as the principal regulating instance for all life processes. The processes of morphogenesis, growth, differentiation and regeneration are also explained by the structuring and regulating activity of the coherent biophoton field. The holographic biophoton field of the brain and the nervous system, and maybe even that of the whole organism, may also be basis of memory and other phenomena of consciousness, as postulated by neurophysiologist Karl Pribram an others. The consciousness-like coherence properties of the biophoton field are closely related to its base in the properties of the physical vacuum and indicate its possible role as an interface to the non-physical realms of mind, psyche and consciousness.

 

The discovery of biophoton emission also lends scientific support to some unconventional methods of healing based on concepts of homeostasis (self-regulation of the organism), such as various somatic therapies, homeopathy and acupuncture. The "ch'i" energy flowing in our bodies' energy channels (meridians) which according to Traditional Chinese Medicine regulates our body functions may be related to node lines of the organism's biophoton field. The "prana" of Indian Yoga physiology may be a similar regulating energy force that has a basis in weak, coherent electromagnetic biofields.

  

Background

 

First discovered in 1923 by Russian medical scientist Professor Alexander G.Gurvich (who named them "mitogenetic rays") and in the 1930s widely researched in Europe and the USA, biophotons have been rediscovered and backed since the 1970s by ample experimental and theoretical evidence by European scientists. In 1974 German biophysicist Fritz-Albert Popp has proved their existence, their origin from the DNA and later their coherence (laser-like nature), and has developed biophoton theory to explain their possible biological role and the ways in which they may control biochemical processes, growth, differentiation etc. Popp's biophoton theory leads to many startling insights into the life processes and may well provide one of the major elements of a future theory of life and holistic medical practice based on such an approach. The importance of the discovery has been confirmed by eminent scientists such as Herbert Froehlich and Nobel laureate Ilya Prigogine. Since 1992, the International Institute of Biophysics, a network of research laboratories in more than 10 countries, based in Germany, is coordinating research in this field which promises rapid development in the next decade.

Aims of the book

To date the few books about biophotons have been highly technical and written mainly in German. Not even among these, there was any single book integrating all that is known today about this fascinating field of science which is likely to become soon a much discussed topic also in the English-speaking world. The author, who in 1994-95 has served as Managing Director of the International Institute of Biophysics at Neuss (Germany) and still is a member of the Board of Directors of this institute, has closely followed biophoton research since 1977 and so was predestined to write the first comprehensive account of the subject ever made. His aim was to reach a wider public among scientists, medical doctors and the scientifically aware. The book which embeds the more technical parts in a popular treatment of the historical antecedents of the concept of "energy bodies", "life energies" and biolectricity, and to the ages-old scientific controversy between vitalistic and mechanistic trends in biology and medicine, also appeals to a general readership interested in new developments in the biological and physical sciences and in medicine and in their interplay with consciousness research and new age ideas.

1. Elements of a physics of the living

What are photons ? / What are biophotons ? / What is the origin of biophoton emission ? / The coherence of biophotons / Regulation by the biophoton field / The network of light metabolism / The present state of the discussion / Biophoton theory and alternative medicine / Biophoton theory as a basis for a scientific theory of life appropriate to nature / The new concept of the cell / The big network / From the molecular to the field perspective / Significance of the new concept / Will biology turn out to be more fundamental than physics ? / Possibilities of misuse / Which philosophy will prevail ?

PART I. Prehistory

 

2. The Aura

 

The concept of nonmaterial "energy bodies" / Subtle bodies of light / "Mana" and "inner fire" / Indian, Tibetan and Chinese concepts / Visionary concept of the "essential light" of man / Paracelsus' "archaeus"

 

3.Electrobiology and vitalism

Bioelectricity / The vitalistic tradition / Romantic medicine: illness as a developmental crisis / Claude Bernard's homeostasis: self-regulation of the organism

4. Scientific Medicine

At the origin of modern electrophysiology: the injury current / The Berlin school of physiology: the "overcoming" of vitalism / The "Bernstein hypothesis" of the membrane potential: paradigm of the new "scientific medicine" / The link between electricity and life energy is severed / "Scientific medicine" conquers the US and the world / Ehrlich's "receptor theory"

5. From Mesmer to Reich

Mesmer's "animal magnetism" / Baron Reichenbach's "odic force" / Wilhelm Reich's "orgone"

6. The inconquerable aura

Kilner's aura screens / Albert Hofmann: the aura is subjective / A contemporary description of the aura / The biophysical basis of the aura

7. Electromagnetic man

Blondlot's "N-rays" / Hofmann finds "head and hand rays" / An early Swiss pioneer of electrobiology / The beginnings of modern electrobiology: Burr's "electrodynamic field" / Electromagnetic field structure at the beginning of embryonic development / Electrical determination of ovulation / The connection between electrodynamic field and the psyche / Electrical indications of illness / Robert O.Becker rehabilitates Matteucci's injury current / The body's own electrical regeneration system / Successful electrical stimulation of bone repair / The discovery of the "perineural DC system" / Brain and nervous system: a combination of analog and digital information coding ?

PART II: Beginnings

8. Alexander Gurvich and mitogenetic radiation

The onion root experiment of 1922 / Cells emit light at birth and at death / Cellular radiation and cancer / The theory of the biological field / The "unequilibrated molecular complexes" / Gurvich as a pioneer of modern biophysical concepts / The fate of mitogenetic research / The two schools of biophoton research / The reasons for the ending of Western mitogenetic research before World War II / After World War II

9. Fritz-Albert Popp: How a physicist came to the light

The riddle of cancer genesis / Light in the organism ? / The Kaznacheev experiment / The foundations for biophoton theory are laid

10. ....and there was light !

The first rigorous proof for the existence of the cell emission / Enormous enhancement of chemical reactivity / Experimental proof for Prigogine's theory

 

11. A stony way to knowledge

The "imperfection theory" / Lossless circulation of light in the cell / Is plant and animal tissue transparent for light ? / A challenge to laboratory physics / Recognition comes

 

12. From chaos to order : Prigogine's "dissipative structures" and Froehlich's "Bose-condensate"

The biochemical world picture / Dissipative structures / Coherent electromagnetic interactions

13. The bio-informatics of electromagnetic interactions

Our radiation environment / Ionizing radiation / Non-ionizing radiation / UV radiation / UV light and the immune system / The visible light / The role of the pineal / Antagonistic effects of colored light / How light enters into the body / Fundamental light sensitivity / High-frequency radiation / Electromagnetic pollution / Two opposite views on biological communication / ULF, ELF and VLF (low frequency) radiation / Weather radiation / The correspondence between weather radiation and brainwaves / On the search for a new explanation of radiation effects

14. A scientific revolution

Meaningful event or blind mechanism ? / The Berlin and the Goettingen schools of thought / An antipode of molecular biology: Georges Lakhovsky / A pioneer of the new thinking: Vladimir Vernadsky / Presman's revolutionary concept / New approaches come to prevail only very slowly / Non-equilibrium thermodynamics and the principle of least effort / The two currents in science: mechanists vs. vitalists / Quantitative power thinking versus the wisdom of non-violence / The intelligence of nature

PART III . Fundamentals

15. The ecology and the physiology of light

The radiation of the sun and the self-regulation of "Gaia". Photosynthesis / Skin and eyes as "light valves" / The role of melanin in the transduction of light

16. Organisms as light stores

Coherent sunlight / The cavity model / Hyperbolic decay / Organisms are biological lasers

17. DNA: Light storage in spiral molecules

Replication / Repair / Transcription / Translation / DNA hyperstructures / The ethidium bromide experiment / DNA the most important source of biophoton emission / The exciplex model of DNA / DNA as lasering matter / The origin of Schroedinger's "order suction" (?) : Bose-condensation in DNA / Photon-phonon-interaction / DNA as a pulsating "light pump" / A hierarchy of light-active molecule systems / Molecular and cellular pulsations / Melanins as collaborators of DNA ? / DNA predestined to be the central control of the biophoton field / The antenna geometry of DNA

18. Coherent states: Organisms at the threshold between Yin and Yang

The bioplasma concept / The biological laser field: dynamic stability at the laser threshold / The peculiarity of biological coherence / The Dicke theory and "Cavity Quantum Electrodynamics" / Actual and potential information / Biological consequences

19. The genesis and development of life in the biophoton field

Matter consists of vibrations / Particles and fields originate from the "void" / Quantum physics treats reality according to acustical laws / Jenny's "cymatics" as a model of morphogenesis / The basic mechanism of morphogenesis: Interference / The importance of frequency / Light as the organizing principle of matter / Material structures as antennae for radiation / Evolution in the radiation field / The communication experiments / The residual light amplifier makes biophotons visible for the first time / When blood cells communicate / Evolution as the expansion of coherent states

20. The biophoton field as morphogenetic field: The development of the embryo

Field properties of organisms / The field description of the cleaving process shows harmonical laws / Holographic properties / Further stages of embryonic development: The dialectics of internal and surface cellular fields / The transition from cleavage to gastrulation: From point symmetry to axial symmetry / The genesis of partial fields / The phase of the genesis of germinal layers: a sensitive stage

21. The three germinal layers

Germinal layers as energy systems / Dissimilar degree of coherence of the three systems

22. The regulation of differentiation and growth by the biophoton field

Properties of organisms that are not determined by genetic activity / junk genes ? / The "c value paradoxon" / Non-genetic role of DNA ? / The exciplex model of DNA solves open problems in biology / The complementarity of growth and differentiation / The electromagnetic model of cell differentiation and growth confirmed experimentally

23. Biochemical regulation

Coordinated and ordered biochemical activity through the biophoton field / The biochemistry of the cell in a new light / The role of photon frequencies and of the particle geometry / Dynamical structuring of the regulating field / Are biological rhythms controlled by the biophoton field ? / Homeostasis through light-controlled entropy gradients / The entire metabolic work accomplished by biophotons ?

24. Harmonical structures

Mitotic spindle ordered by cavity waves ? / Microtubuli as optical waveguides ? / Cell skeleton built up by light ? / The role of water / Order and water metabolism in the cell are linked / Vibrating musculature / A complex resonance structure makes the organism react very sensitively / States of tension / Biophotons in the nervous system / Holographic biophoton fields in the brain / Altered states of consciousness / A coupling between the nervous system and other oscillators in the organism ? / Our odorous aura

PART IV. Applications

25. Illness and health

Health as a coherent state / Illness as a developmental crisis / Stages of illness / Immunological resistance and effectiveness of substances explainable through biophoton field

26. Regulation forms and types of illness

Polar ordering of regulation systems / Reactive types and the proneness towards certain illnesses / Yin and Yang illnesses / Pischinger's "Basic regulatory system" as a basis for all regulations

27. Cancer: Loss of coherence and of the ability to store light

Cancer tissue has different emission / The tumor is the symptom, not the illness / A fast and cheap tumor test

28. Homeopathic principles as a "guiding line" for modern medicine

Holistic regulation through vibrations / High potencies improve the coherence of the organism and are effective on the causal level / Homeopathic effects not explainable biochemically / Electromagnetic fields can substiute substances / The memory of water / Coherence therapy

29. Urine, blood, and breath tests; smoking test

The luminescence of urine indicates illnesses / Has blood radiation a diagnostic value ? / Blood and urine of smokers show stronger emission / Luminescent breath

30. A test for determining immunological resistance

Radiant phagocytes / A Tibetan drug under test / Biophoton measurements on the flu remedy Echinacine

31. Food quality analysis

In fact we eat sunlight / A concentration of the sunlight towards DNA / ATP as a light carrier / Not the caloric but the information content determines the quality of foodstuffs / The light storage capacity of the "living macromolecules" / Fats and sunlight / A test system for Popp's hypothesis / Free range eggs clearly distinguishable from battery eggs / Is it possible to discriminate biological from conventional foodstuffs ? / Different production and fertilization methods as well as contamination by pesticides and heavy metals engender different biophoton emissions / Bacterial contamination in beer can be detected at an early stage / Biophoton method is superior to biochemical analysis in some essential aspects / The result in the controversy about biological products / Detection of oxidative degradation of organic substances

32. Agriculture

Improvement of quality and yield through "resonance stimulation" by laser light / Bad quality and low resistance of glass-house products due to lack of UV light / Electromagnetic stimulation of growth (electroculture) / Acoustic stimulation of plant growth

33. Water research and "biological activity"

Water - an enigmatic substance / Water structures - facts and speculations / The memory of water / Are biological experiments and biophoton measurements more adequate than other methods of investigation ? / Is the structural aspect of water overemphasized ? / Different types of water can be differentiated / The discrimination of natural and synthetic substances based on their "biological activity"

34. Environmental pollution

Gaseous pollutants / Biophoton emission as a measure of the Relative Biological Effectiveness (RBE) of ionizing radiation / Synergetic mechanisms of damage

35. Dying forests

Water lentils as bio-indicators / Nuclear plants and dying forests: is there a connection ? / Electrochemical smog and dying forests

36. Methods of bioelectronic diagnosis

1. The Bioelectronic Test according to Vincent / Bioelectronic measurements of body fluids to assess Claude Bernard's "terrain" / Cancer prognosis possible ?

2. Electroacupuncture / Electroacupuncture according to Voll (EAV) / Electroacupuncture according to Croon ("Electroneural diagnostics") / The "Ryodoraku method" of Nakatani / The AMI method of Motoyama

3. The bases of acupuncture / A possible participation of meridians in the formation of embryonic organs / Meridians may be not material channels but node lines of the biophoton field / Acupuncture points electrically distinguished / A new method shows if someone is healthy or ill / The stimulation of acupuncture points / Biophoton research furnishes bases for electrodiagnostics

4. Kirlian photography / Between bioelectrical measurement and biophoton measurement / Distribution of electrical charge on the skin is fundamental / Diagnostic evaluation still in its beginnings / New technical developments / Use for quality analysis of foodstuffs and liquids

5. Whole body biophoton diagnostics / The biophysical basis of the aura / The works of Gulyaev and Godik / Thermoregulation diagnostics / Biophoton measurements on humans / "Hand radiation" and healers / The whole-body biophoton diagnostics project

37. Methods of bioelectronic therapy

1. MORA and radionics

2. Electrotherapy / An old tradition / Electrotherapy in the 19th century / High-frequency AC therapy / ELF therapy

3. Chromotherapy (Therapy with colored light) / Ghadiali's chromotherapy / Beginnings of modern light therapy / The actual situation of chromotherapy

4. Laser therapy / Soft-laser applications with weak light / The work of Inyushin / Laser stimulation of tissue regeneration / Laser stimulation of acupuncture points / The mechanism of soft laser therapy / Resonance stimulation of the biophoton field

PART V. Outlook

38. The biophoton field - mediator between body and soul ?

Biophotons - to be analysed in the framework of current science / Is there an even more fundamental level of the organism "behind" the biophoton field ? / The rebirth of the "ether" / The zero-point energy of the vacuum / Bearden's "scalar fields" / Wheeler's "quantum foam" / Bohm's "implicate order" / Burkhard Heim's six-dimensional world model / Photons as mediators between matter and spirit ? / The consciousness-like aspects of matter / Coherence as a bridge to the realm of consciousness / Biophoton theory and the vacuum field / Organisms may control their own space structure and flow of time: Dubrov's theory of "biogravitation" / Pulsation between space and "counter-space": biological space and the ether in the anthroposophical doctrine / The polarity between levity and gravity / The pulse of life

 

Marco Bischof

522 pp., more than 160 illustrations, 5 color plates, extensive bibliography and index.

German publisher: Zweitausendeins, Frankfurt.

www.zweitausendeins.de/

Publication date: March 1995

Actual edition (May 1998): 9th printing

Total number of copies sold in German-language market: 27'000

ISBN 3-86150-095-7

World rights: Zweitausendeins.

showcase Exquisite...Vitrine Exquise: Avec la participation de Art Orienté Objet, James Lee Byars, Jimmie Durham, ExtraLucide, Olivier Mosset, Matt Mullican, Rebecca Purcell, Dana Sherwood, Morgane Tschiember, Robert Williams et Raphaël Zarka. Commissariat : Sarina Basta

The Hornet is a high speed heavily armoured Interceptor capable of acceleration in excess of 100 G's, carrying a payload of two 12 megaton naquadah enhanced nuclear warheads fitted with shield oscillators to bypass and enemy shield and impact the hull, also contains 8 self guided energy missiles that seek and pass through enemy hull plating, and can be used to cause damage to larger enemy vessels as well as fighter/interceptors.

 

Employed as a tactical assault vehicle used mainly as a first strike interceptor to attack an enemy fleet's command vessel, to then get the hell out of the system before they can be shot down or captured.

 

Sorry..crap backstory..but I just whipped this up with what I had laying around.

This is what I do : magneticpic.com/blog/2013/2/things-i-do-when-i-dont-take-...

 

Strobist : 1 elinchrome quadra (minimum power) flown above subject inside octa softbox, 1 sb900 gelled blue under the table, 1 sb600 with snoot for accent light on Synthesizer

Robert Moog, Buffalo, NY/USA, 1978

 

Der Mini-moog kam 1970 in den Handel. Bereits nach einem Jahr war er Standard-Instrument vieler bekannter Musiker und Gruppen. Dieser Erfolg führte zu einer für elektronische Instrumente sehr langen Bauzeit, die Produktion endete erst 1981. Auch danach ist der Mini-Moog noch lange eingesetzt worden.

 

Die Klangerzeugung erfolgt durch drei Oszillatoren mit je sechs Schwingungsformen (Dreieck-, Sägezahn- und drei Rechteckschwingungen). Filter dämpfen oder unterdrücken einzelne Frequenzen aus diesen unterschiedlichen Schwingungen. So läßt sich eine Vielzahl von klangen und Geräuschen erzeugen.

 

Einstimmig spielbarer Analogssynthesizer, subtraktive Klangsynthese, 44 Plastiktasten, 2 Handräder.

________________________________________

The Mini Moog was introduced to the market in 1970. Within a year it became a standard instrument for many well-known musicians and bands. The Mini Moog was a great success and, in terms of electric musical instruments, was produced and sold for a long time. Manufacturing did not end until 1981. The Mini Moog continued to be used for a long time even after production stopped.

 

Three oscillators with six wave-forms each (triangle waves, saw-tooth waves and three square waves) were responsible for generating sound. Filters were used to dampen or suppress certain frequencies of these waves. This permitted a wide range of sounds and noises to be produced.

 

Analog synthesizer with one-voice play operation, subtractive sound synthesis, 44 plastic keys, 2 hand-wheels.

I photographed my copy of the book on my kitchen counter in Tucson, Arizona

 

In Schrödinger's cat experiment, a cat, a flask of poison, and a radioactive source connected to a Geiger counter are placed in a sealed box. As illustrated, the objects are in a state of superposition: the cat is both alive and dead.

 

In quantum mechanics, Schrödinger's cat is a thought experiment that illustrates a paradox of quantum superposition. In the thought experiment, a hypothetical cat may be considered simultaneously both alive and dead, while it is unobserved in a closed box, as a result of its fate being linked to a random subatomic event that may or may not occur. This thought experiment was devised by physicist Erwin Schrödinger in 1935[1] in a discussion with Albert Einstein[2] to illustrate what Schrödinger saw as the problems of the Copenhagen interpretation of quantum mechanics.

 

In Schrödinger's original formulation, a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor (e.g. a Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation implies that, after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other.

 

Though originally a critique on the Copenhagen interpretation, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. The scenario is often featured in theoretical discussions of the interpretations of quantum mechanics, particularly in situations involving the measurement problem. The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. As a result, Schrödinger's cat has had enduring appeal in popular culture. Experiments at the atomic scale have been carried out, showing that very small objects may be superimposed; superimposing an object as large as a cat would pose considerable technical difficulties.

 

Fundamentally, the Schrödinger's cat experiment asks how long superpositions last and when (or whether) they collapse. Interpretations for resolving this question include that the cat is dead or alive when the box is opened (Copenhagen); that a conscious mind must observe the box (Von Neumann–Wigner); that upon observation, the universe branches into one universe where the cat is alive and another one where it is dead (many-worlds); that every object (such as the cat, and the box itself) is an observer, but superposition is relative depending on the observer (relational); that superposition never truly exists due to time-travelling waves (transactional); that merely observing the box either slows or accelerates the cat's death (quantum Zeno effect); among other theories that assert that the cat is dead or alive long before the box is opened. It is unclear which interpretation is correct; the underlying issue raised by Schrödinger's cat remains an unsolved problem in physics.

  

Origin And Motivation

Schrödinger intended his thought experiment as a discussion of the EPR article—named after its authors Einstein, Podolsky, and Rosen—in 1935.[3][4] The EPR article highlighted the counterintuitive nature of quantum superpositions, in which a quantum system such as an atom or photon can exist as a combination of multiple states corresponding to different possible outcomes.

 

The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by, the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with multiple particles separated by large distances can be in such a superposition. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an unstable keg of gunpowder will, after a while, contain a superposition of both exploded and unexploded states.[4]

 

To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.[1]

 

Since Schrödinger's time, various interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real, others do not.[5][6] Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a touchstone for modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses.[7]

  

Thought experiment

Schrödinger wrote: [1][8]

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives. if meanwhile, no atom has decayed. The first atomic decay would have poisoned it. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.

 

It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naïvely accepting as valid a "blurred model" for representing reality. In itself, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.

 

Schrödinger's famous thought experiment poses the question, "When does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial linear combination of states, each of which resembles different classical states, and instead begin to have a unique classical description?) If the cat survives, it remembers only being alive. But explanations of the EPR experiments that are consistent with standard microscopic quantum mechanics require that macroscopic objects, such as cats and notebooks, do not always have unique classical descriptions. The thought experiment illustrates this apparent paradox. Our intuition says that no observer can be in more than one state simultaneously—yet the cat, it seems from the thought experiment, can be in such a condition. Is the cat required to be an observer, or does its existence in a single well-defined classical state require another external observer? Each alternative seemed absurd to Einstein, who was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:

 

You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality — reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.[9]

 

Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.[4]

  

Interpretations

 

Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or whether) they collapse.

 

Copenhagen interpretation

 

Main article: Copenhagen interpretation

A commonly held interpretation of quantum mechanics is the Copenhagen interpretation.[10] In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat" and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

  

Von Neumann interpretation

 

Main article: Von Neumann–Wigner interpretation

In 1932, John von Neumann described in his book Mathematical Foundations a pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses.[11] This potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple.[12] Neumann asserted that a conscious observer is necessary for collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a wave function. This interpretation was later adopted by Eugene Wigner, who then rejected the interpretation in a thought experiment known as Wigner's friend.[13]

  

Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely.[13]

  

Bohr's interpretation

 

One of the main scientists associated with the Copenhagen interpretation, Niels Bohr, offered an interpretation that is independent of a subjective observer-induced collapse of the wave function, or of measurement; instead, an "irreversible" or effectively irreversible process causes the decay of quantum coherence, which imparts the classical behavior of "observation" or "measurement".[14][15][16][17] Thus, Schrödinger's cat would be either dead or alive long before the box is observed.[18]

 

A resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred.[19] Analysis of an actual experiment by Roger Carpenter and A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result.[20] The apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but they don't consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches.[11] However, it is disputed whether merely observing the color counts as a conscious observation of the outcome.[21]

  

Many-worlds interpretation and consistent histories

 

Main article: Many-worlds interpretation

In 1957, Hugh Everett formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are decoherent from each other. In other words, when the box is opened, the observer and the possibly dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no effective communication or interaction between them.

 

When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is entangled, or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. The same mechanism of quantum decoherence is also important for the interpretation in terms of consistent histories. Only the "dead cat" or the "live cat" can be a part of a consistent history in this interpretation. Decoherence is generally considered to prevent simultaneous observation of multiple states.[22][23]

 

A variant of the Schrödinger's cat experiment, known as the quantum suicide machine, has been proposed by cosmologist Max Tegmark. It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.

  

Ensemble interpretation

 

The ensemble interpretation states that superpositions are nothing but subensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of this interpretation state that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue.

  

This interpretation serves to discard the idea that a single physical system in quantum mechanics has a mathematical description that corresponds to it in any way.[24]

  

Relational interpretation

 

The relational interpretation makes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction evolution, and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.[25] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead.

  

Transactional interpretation

 

In the transactional interpretation, the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of the wavefunction is "atemporal" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.[26]

  

Zeno effects

 

The Zeno effect is known to cause delays to any changes from the initial state.

 

On the other hand, the anti-Zeno effect accelerates the changes. For example, if you peek a look into the cat box frequently you may either cause delays to the fateful choice or, conversely, accelerate it. Both the Zeno effect and the anti-Zeno effect are real and known to happen to real atoms. The quantum system being measured must be strongly coupled to the surrounding environment (in this case to the apparatus, the experiment room ... etc.) in order to obtain more accurate information. But while there is no information passed to the outside world, it is considered to be a quasi-measurement, but as soon as the information about the cat's well-being is passed on to the outside world (by peeking into the box) quasi-measurement turns into measurement. Quasi-measurements, like measurements, cause the Zeno effects.[27]

Zeno effects teach us that even without peeking into the box, the death of the cat would have been delayed or accelerated anyway due to its environment.

  

Objective collapse theories

 

According to objective collapse theories, superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself" or "the environment observes the cat".

 

Objective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.[28] These theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states has been proposed as a precise detector of the quantum gravity related energy decoherence models.[29]

  

Applications and tests

 

Schrödinger's cat quantum superposition of states and effect of the environment through decoherence

The experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of relatively large (by the standards of quantum physics) objects have been performed.[30][better source needed] These experiments do not show that a cat-sized object can be superposed, but the known upper limit on "cat states" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near absolute zero.

 

A "cat state" has been achieved with photons.[31]

A beryllium ion has been trapped in a superposed state.[32]

An experiment involving a superconducting quantum interference device ("SQUID") has been linked to the theme of the thought experiment: "The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state."[33]

A piezoelectric "tuning fork" has been constructed, which can be placed into a superposition of vibrating and non-vibrating states. The resonator comprises about 10 trillion atoms.[34]

An experiment involving a flu virus has been proposed.[35]

An experiment involving a bacterium and an electromechanical oscillator has been proposed.[36]

In quantum computing the phrase "cat state" sometimes refers to the GHZ state, wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g.,

  

|\psi \rangle ={\frac {1}{\sqrt {2}}}{\bigg (}|00\ldots 0\rangle +|11\ldots 1\rangle {\bigg )}.

According to at least one proposal, it may be possible to determine the state of the cat before observing it.[37][38]

  

Extensions

 

Prominent physicists have gone so far as to suggest that astronomers observing dark energy in the universe in 1998 may have "reduced its life expectancy" through a pseudo-Schrödinger's cat scenario, although this is a controversial viewpoint.[39][40]

  

In August 2020, physicists presented studies involving interpretations of quantum mechanics that are related to the Schrödinger's cat and Wigner's friend paradoxes, resulting in conclusions that challenge seemingly established assumptions about reality.[41][42][43]

  

See also

 

iconPhysics portal

Basis function

Complementarity (physics)

Double-slit experiment

Elitzur–Vaidman bomb tester

Heisenberg cut

Modal realism

Observer effect (physics)

Schroedinbug

Schrödinger's cat in popular culture

References

  

^ a b c Schrödinger, Erwin (November 1935). "Die gegenwärtige Situation in der Quantenmechanik (The present situation in quantum mechanics)". Naturwissenschaften. 23 (48): 807–812. Bibcode:1935NW.....23..807S. doi:10.1007/BF01491891. S2CID 206795705.none

Fine, Arthur. "The Einstein-Podolsky-Rosen Argument in Quantum Theory". Stanford Encyclopedia of Philosophy. Retrieved 11 June 2020.none

Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? Archived 2006-02-08 at the Wayback Machine A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935)

^ a b c Fine, Arthur (2017). "The Einstein-Podolsky-Rosen Argument in Quantum Theory". Stanford Encyclopedia of Philosophy. Stanford University. Retrieved 11 April 2021.none

Polkinghorne, J. C. (1985). The Quantum World. Princeton University Press. p. 67. ISBN 0691023883. Archived from the original on 2015-05-19.none

Tetlow, Philip (2012). Understanding Information and Computation: From Einstein to Web Science. Gower Publishing, Ltd. p. 321. ISBN 978-1409440406. Archived from the original on 2015-05-19.none

Lazarou, Dimitris (2007). "Interpretation of quantum theory - An overview". arXiv:0712.3466 [quant-ph].none

Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society. 124 (5): 323–338. JSTOR 986572.none Reproduced with some inaccuracies here: Schrödinger: "The Present Situation in Quantum Mechanics." 5. Are the Variables Really Blurred?

Maxwell, Nicholas (1 January 1993). "Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity". The British Journal for the Philosophy of Science. 44 (2): 275–305. doi:10.1093/bjps/44.2.275. JSTOR 687649.none

Wimmel, Hermann (1992). Quantum physics & observed reality: a critical interpretation of quantum mechanics. World Scientific. p. 2. ISBN 978-981-02-1010-6. Archived from the original on 20 May 2013. Retrieved 9 May 2011.none

^ a b Hobson, Art (2017). Tales of the Quantum: Understanding Physics' Most Fundamental Theory. New York, NY: Oxford University Press. pp. 200–202. ISBN 9780190679637. Retrieved April 8, 2022.none

Omnès, Roland (1999). Understanding Quantum Mechanics. Princeton, New Jersey: Princeton University Press. pp. 60–62. ISBN 0-691-00435-8. Retrieved April 8, 2022.none

^ a b Levin, Frank S. (2017). Surfing the Quantum World. New York, NY: Oxford University Press. pp. 229–232. ISBN 978-0-19-880827-5. Retrieved April 8, 2022.none

John Bell (1990). "Against 'measurement'". Physics World. 3 (8): 33–41. doi:10.1088/2058-7058/3/8/26.none

Niels Bohr (1985) [May 16, 1947]. Jørgen Kalckar (ed.). Foundations of Quantum Physics I (1926-1932). Niels Bohr: Collected Works. Vol. 6. pp. 451–454.none

Stig Stenholm (1983). "To fathom space and time". In Pierre Meystre (ed.). Quantum Optics, Experimental Gravitation, and Measurement Theory. Plenum Press. p. 121. The role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966).none

Fritz Haake (April 1, 1993). "Classical motion of meter variables in the quantum theory of measurement". Physical Review A. 47 (4): 2506–2517. Bibcode:1993PhRvA..47.2506H. doi:10.1103/PhysRevA.47.2506. PMID 9909217.none

Faye, J (2008-01-24). "Copenhagen Interpretation of Quantum Mechanics". Stanford Encyclopedia of Philosophy. The Metaphysics Research Lab Center for the Study of Language and Information, Stanford University. Retrieved 2010-09-19.none

Puri, Ravinder R. (2017). Non-Relativistic Quantum Mechanics. Cambridge, United Kingdom: Cambridge University Press. p. 146. ISBN 978-1-107-16436-9. Retrieved April 8, 2022.none

Carpenter RHS, Anderson AJ (2006). "The death of Schrödinger's cat and of consciousness-based wave-function collapse" (PDF). Annales de la Fondation Louis de Broglie. 31 (1): 45–52. Archived from the original (PDF) on 2006-11-30. Retrieved 2010-09-10.none

Okón E, Sebastián MA (2016). "How to Back up or Refute Quantum Theories of Consciousness". Mind and Matter. 14 (1): 25–49.none

Zurek, Wojciech H. (2003). "Decoherence, einselection, and the quantum origins of the classical". Reviews of Modern Physics. 75 (3): 715. arXiv:quant-ph/0105127. Bibcode:2003RvMP...75..715Z. doi:10.1103/revmodphys.75.715. S2CID 14759237.none

Wojciech H. Zurek, "Decoherence and the transition from quantum to classical", Physics Today, 44, pp. 36–44 (1991)

Smolin, Lee (October 2012). "A real ensemble interpretation of quantum mechanics". Foundations of Physics. 42 (10): 1239–1261. arXiv:1104.2822. Bibcode:2012FoPh...42.1239S. doi:10.1007/s10701-012-9666-4. ISSN 0015-9018. S2CID 118505566.none

Rovelli, Carlo (1996). "Relational Quantum Mechanics". International Journal of Theoretical Physics. 35 (8): 1637–1678. arXiv:quant-ph/9609002. Bibcode:1996IJTP...35.1637R. doi:10.1007/BF02302261. S2CID 16325959.none

Cramer, John G. (July 1986). The transactional interpretation of quantum mechanics. Vol. 58. Reviews of Modern Physics. pp. 647–685.none

"How the quantum Zeno effect impacts Schrodinger's cat". phys.org. Archived from the original on 17 June 2017. Retrieved 18 June 2017.none

Okon, Elias; Sudarsky, Daniel (2014-02-01). "Benefits of Objective Collapse Models for Cosmology and Quantum Gravity". Foundations of Physics. 44 (2): 114–143. arXiv:1309.1730. Bibcode:2014FoPh...44..114O. doi:10.1007/s10701-014-9772-6. ISSN 1572-9516. S2CID 67831520.none

Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (2016-08-11). "Large energy superpositions via Rydberg dressing". Physical Review A. 94 (2): 023408. arXiv:1509.01303. Bibcode:2016PhRvA..94b3408K. doi:10.1103/physreva.94.023408. ISSN 2469-9926. S2CID 118364289.none

"What is the world's biggest Schrodinger cat?". stackexchange.com. Archived from the original on 2012-01-08.none

"Schrödinger's Cat Now Made Of Light". www.science20.com. 27 August 2014. Archived from the original on 18 March 2012.none

Monroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (1996-05-24). "A "Schrödinger's cat" Superposition State of an Atom". Science. 272 (5265): 1131–1136. Bibcode:1996Sci...272.1131M. doi:10.1126/science.272.5265.1131. PMID 8662445. S2CID 2311821.none

"Physics World: Schrödinger's cat comes into view". 5 July 2000.none

Scientific American : Macro-Weirdness: "Quantum Microphone" Puts Naked-Eye Object in 2 Places at Once: A new device tests the limits of Schrödinger's cat Archived 2012-03-19 at the Wayback Machine

Romero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). "Toward Quantum Superposition of Living Organisms". New Journal of Physics. 12 (3): 033015. arXiv:0909.1469. Bibcode:2010NJPh...12c3015R. doi:10.1088/1367-2630/12/3/033015. S2CID 59151724.none

"Could 'Schrödinger's bacterium' be placed in a quantum superposition?". physicsworld.com. Archived from the original on 2016-07-30.none

Najjar, Dana (7 November 2019). "Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever". Live Science. Retrieved 7 November 2019.none

Patekar, Kartik; Hofmann, Holger F. (2019). "The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements". New Journal of Physics. 21 (10): 103006. arXiv:1905.09978. Bibcode:2019NJPh...21j3006P. doi:10.1088/1367-2630/ab4451.none

Chown, Marcus (2007-11-22). "Has observing the universe hastened its end?". New Scientist. Archived from the original on 2016-03-10. Retrieved 2007-11-25.none

Krauss, Lawrence M.; James Dent (April 30, 2008). "Late Time Behavior of False Vacuum Decay: Possible Implications for Cosmology and Metastable Inflating States". Phys. Rev. Lett. US. 100 (17): 171301. arXiv:0711.1821. Bibcode:2008PhRvL.100q1301K. doi:10.1103/PhysRevLett.100.171301. PMID 18518269. S2CID 30028648.none

Merali, Zeeya (17 August 2020). "This Twist on Schrödinger's Cat Paradox Has Major Implications for Quantum Theory - A laboratory demonstration of the classic "Wigner's friend" thought experiment could overturn cherished assumptions about reality". Scientific American. Retrieved 17 August 2020.none

Musser, George (17 August 2020). "Quantum paradox points to shaky foundations of reality". Science Magazine. Retrieved 17 August 2020.none

Bong, Kok-Wei; et al. (17 August 2020). "A strong no-go theorem on the Wigner's friend paradox". Nature Physics. 27 (12): 1199–1205. arXiv:1907.05607. Bibcode:2020NatPh..16.1199B. doi:10.1038/s41567-020-0990-x.none

Further reading

  

Einstein, Albert; Podolsky, Boris; Rosen, Nathan (15 May 1935). "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?". Physical Review. 47 (10): 777–780. Bibcode:1935PhRv...47..777E. doi:10.1103/PhysRev.47.777.none

Leggett, Tony (August 2000). "New Life for Schrödinger's Cat" (PDF). Physics World. pp. 23–24. Retrieved 28 February 2020.none An article on experiments with "cat state" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously.

Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society. 124 (5): 323–338. JSTOR 986572.none(registration required)

Yam, Phillip (October 9, 2012). "Bringing Schrödinger's Cat to Life". Scientific American. Retrieved 28 February 2020. A description of investigations of quantum "cat states" and wave function collapse by Serge Haroche and David J. Wineland, for which they won the 2012 Nobel Prize in Physics.

Kalmbach, Gudrun (1983). Orthomodular Lattices. Academic Press.

Longtime customer Herr Kringle came a knockin’ again this year with another epic custom build request. To address a new level of intercontinental delivery challenges this season, we sourced a clean J80 Land Cruiser and upgraded everything, starting with the powertrain.

 

Kringle Spec features a raucous 600 HP delivered to all four wheels through a twin-turbocharged 4.0L V8 coupled with a 16KW plug in hybrid dual motor setup configured to pwn even the biggest obstacles terra firma can conjure.

 

The package is completed by a Portable roof-mounted SatNav Unit working in tandem with our custom Compact Trans-Dimensional Oscillator, enabling Herr Kringle to deliver even the most difficult packages in little more than the space of a wink.

 

I hope you enjoy, and Happy Holidays!

The Fall

 

...

 

Book :

 

Raphaël

Grâce Et Beauté

Skira

2001

 

CD :

 

L. Pierre

Touchpool

Melodic

MELO27

 

Written by Aidan John Moffat

 

Photography by Nadia Bradley

 

iTunes :

 

Stereolab

Lo Boob Oscillator

Duophonic

DUHF09

 

GMA For Pleasure ...

  

A chaotic transient and trap orbit in the double-well electronic oscillator.

 

The time series view is in the picture above. The circle on the left is the trapped orbit in one half of the double-well. The circuit takes an unpredictable time to trap, being chaotic (in the technical sense).

When I started my career with IBM, one of my co-workers was a very interesting engineer, Marvin K. He was extremely intelligent and curious about many things, including astronomy, science, electronics and photography.

About a year after his death in 2004, his wife called me and said that she had a ham radio that he had built as a teenager and she thought I might like to have it. After I brought it home, I noticed that curled inside of the large copper coil, were several sheets of hand-written notes that described a lot about the construction and early use of this very basic radio transmitter. Typical of Marvin, the note was very detailed and contained a great deal of information about the radio. Here is that note...

 

"This is the short-wave amateur radio transmitter I built when I was age 13 in 1931-1932 in Sac City, Iowa. I operated under the call letters of W9AZA issued for the 80 meter CW band of 3.5 to 3.9 kilocycles per second (now called Kilo Hertz, or KHz, continuous wave, where the transmitter is keyed on and off with a telegraph-type key, using International Morse Code, NO voice operation)

This transmitter is a self-excited, push-pull oscillator, using two type ’45 tubes, where a heavy radio frequency current is generated, which oscillated back and forth at the resonant frequency of a tuned circuit consisting to two things: the large copper coil and the main tuning capacitor (or ‘condenser’). Energy is electromagnetically coupled to the two smaller copper coils which are connected to another tuning capacitor and the antenna system. This provides another resonant circuit which is tuned to the same radio frequency as the oscillator. Energy is then radiated from the antenna system…which was a zeppelin-type antenna with a 132 foot flat top, end fed with two parallel wires spaced 8 inches apart, one connected to one end of the 132’ antenna, the other one dead ended there..(not connected).

A separate power supply provided power to this transmitter. It consisted of a 115-volt AC power transformer, one type ’80 rectifier tube, two 8mfd, 450 volt filter capacitors, a filter choke and bleeder resistor. The transformer also supplied 5 volts AC for the ’80 tube filaments, 2 ½ volts AC for the ’45 tube filaments and 500 to 600 volts AC, center-tapped, for the nominally 250 to 300 volts DC for the transmitter tube plates. Plate power input to the transmitter oscillator circuit was maybe 20 or 30 watts, maximum. (I couldn’t afford voltmeters or ammeters which would have told me more...!) My radius of operation was Iowa and the adjacent states – seldom further.

My short-wave receiver was initially a 1 tube regenerative receiver I built and later a Super Wasp receiver, that my neighbor across the street had built and had replaced with a more up-to-date factory-built SW receiver. The Pilot Super-Wasp required a 6-volt car-battery for the tube filaments and a B- battery eliminator (connected to the 115 volts DC house current) for the 45, 90 and 180 volts DC the receiver used. It had plug-in coils to cover the 20, 40 80 and 160 meter amateur bands, as well as the broadcast band. It was regenerative also.

I operated mainly from 1932 thru 1940. The license had to be renewed, with proof of use, every 3 years or so. I finally let it run out….should have kept it active. My license was W9AZA, was a re-issue and came out when the W9K ---‘s (a very early call)...were coming out. My neighbor got W9KDL as the same time I got mine. He helped me, and we practiced code together via a telegraph line he installed between his house, mine and another 1 block away and one more a mile away..!

 

The plastic cover over the transmitter is not part of the original, but is just to keep the dust off. The cover, from an IBM type 650 scientific computer magnetic drum (circa 1955-1960) just happened to be the right size…!"

 

Photo info...shot with a Nikon D750 and Nikon 70-180mm Macro lens. Lit with a single Alien Bee and a gold reflector. This was a focus stack of a dozen exposures, all blended with CombineZP.

  

Needs your free vote of support at: goo.gl/heBmZ7

 

With enough votes, it could be made into an actual set by LEGO!

 

Also, please check out my Minimoog models at: goo.gl/iucWKS

 

AND

 

the Prism & Spectrum at: goo.gl/pFTr3v

A longer chaotic transient in the double-well electronic oscillator, followed by trapping into one of the wells. The phase plane portrait is in the next picture.

nrhp # 87001463- The Highland Light (previously known as Cape Cod Light) is an active lighthouse on the Cape Cod National Seashore in North Truro, Massachusetts. The current tower was erected in 1857, replacing two earlier towers that had been built in 1797 and 1831. It is the oldest and tallest lighthouse on Cape Cod.[5]

 

The grounds are open year-round, while the light is open to the public from May until late October, with guided tours available. Highland Light is owned by the National Park Service, and was cared for by the Highland Museum and Lighthouse, Inc. until 2014 when Eastern National, another non-profit group, took over the contract to operate the facility as a tourist attraction.[6] The United States Coast Guard operates the light as an aid to navigation.[7] The United States Navy ship USS Highland Light (IX-48) was named after the light. It is listed on the National Register of Historic Places as Highland Light Station.

 

In 1797, a station authorized by George Washington was established at this point on the Cape, with a wood lighthouse to warn ships about the dangerous coastline between Cape Ann and Nantucket. It was the first light on Cape Cod. In 1833, the wood structure was replaced by a brick tower and in 1840 a new lantern and lighting apparatus was installed. In 1857 the lighthouse was declared dangerous and demolished, and for a total cost of $17,000, the current 66-foot brick tower was constructed.[8]

 

On June 6, 1900, the light was changed from a fixed beam to flashing, with a new. The new Barbier, Benard & Turenne first-order Fresnel lens had four panels of 0.92 meter focal distance, revolved in mercury, and gave, every five seconds, flashes of about 192,000 candlepower nearly one-half second in duration. While the new lens was being installed, the light from a third-order lens was exhibited atop a temporary tower erected near the lighthouse; it was later sold at auction. The Highland Light was then the most powerful on the east coast of the United States. Two four-horsepower oil engines with compressors operated by an engine fueled by kerosene, were added to ensure that the fog signal could be activated within ten minutes instead of the previous 45. A new fog signal was installed in 1929, an electrically operated air oscillator, to make it audible over a greater distance.[6]

 

The lighthouse was converted to electric operation in 1932 with a 1000-watt beacon. In 1946, Highland Light's Fresnel lens was replaced by modern aerobeacons, first by a Crouse-Hinds DCB-36 double rotating light and then by a Carlisle & Finch DCB-224, with a second unit as backup. Unfortunately, the Fresnel lens was severely damaged when it was removed, but fragments are on display in the museum on site. The light was fully automated by 1986 with a Crouse-Hinds DCB-224 rotating beacon.[9][6] In 1998, a VRB-25 optical system was installed.[3][6] Most recently, the light source is a Vega Marine LED beacon model 44/2.5 installed in April 2017.[10]

 

The current location of the lighthouse is not the original site. It was in danger of falling down the cliff due to beach erosion, so the structure was moved 450 feet (140 m) to the west. The government funding to do so was supplemented by money raised through fund raising by the Truro Historical Society.[11] The move was accomplished by International Chimney Corp. of Buffalo, New York and Expert House Movers of Maryland over a period of 18 days in July, 1996.[3][6] The move left the light station on Cape Cod National Seashore property, bordering the Highland Golf Course. After an errant golf ball broke a window, they were replaced with unbreakable material. In 1998, the keeper's house was modified to be a gift shop and museum. The lighthouse grounds are open year-round on Highland Light Road in Truro, with tours and the museum available from a National Park Service partner, Eastern National,[12] during the summer months.

 

from Wikipedia

Generative drawing with particles, attractors, repelers and oscillators.

 

Armed with a Sonic Oscillator Heat Ray capable of melting steel out to 500 yards, the M6A7 is part of a long secret Pentagon energy weapons research program dating back to the late 1930s. Built out of inspiration from the Operation Chitown group. Here's the sound it makes when it fires btw: www.flickr.com/photos/js9productions/5975439246/

In my effort to continue my 365 Project and to combat these ugly, rainy, cold days that get dark before I even get off work, I have to expand the types of photographs that I've been taking as well as the photo subjects. I took this board out of an old stock radio from my wife's previous car that we no longer own. It was just sitting out in the garage, so...why not?!?

 

Technical Information:

Camera - Nikon D5000

Lens – Nikkor 50mm Fixed

ISO – 160

Aperture – f/3.5

Exposure – 1/1250 sec

Focal Length – 50mm

 

Final adjustments were made with PS.

 

“For I know the plans I have for you,” declares the LORD, “plans to prosper you and not to harm you, plans to give you hope and a future.” ~Jeremiah 29:11