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

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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.

 

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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.

 

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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].

 

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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].

 

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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.

 

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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).

 

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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].

 

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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/

Taken at Knab Rock , Mumbles today with my phone after watching hail and rain showers pass furiously across the bay,

All photos are copyrighted and cannot be used or linked to without permission. If you are interested in a photo, please visit my web site at Michael Bryan Photography.

 

This is a shot of the sunset this evening in Bartlesville, Oklahoma. We broke a 1923 snowfall record today with 12 to 20 inches falling. Drifts were as high as 5 feet. This morning (2/10/2011) the air temperature is -27F (-33C). This is the coldest temperature ever recorded in Bartlesville Oklahoma. It is hard to believe, but the national weather service is predicting 72F (22C) for next Wednesday (2/16/2011). Only in Oklahoma!!! Global warming? LOL!!!

 

I shoveled a lot of snow today and I don't even want to think about how sore I may be tomorrow. However it was very beautiful.

 

Explore - Feb 9, 2011 #446

 

Copyrighted - All Rights Reserved! No Use Without Permission! www.michaelbryanphoto.com

While predicting where the birds will overnight on this refuge is an iffy proposition, this shallow lake just off the tour-route road is a regular hangout. The trick is to check it out early to see if any pathfinder birds have already selected it. If so, they will continually vocalize to the overflying birds trying to entice them to drop down and join them (increasing safety in numbers). There are several blinds here that you can select for different vantage positions. It's still early, and this lake was eventually completely filled with overnighting birds.

 

IMG_4266; Sandhill Cranes

2500 Q Street NW

As i predicted in my Magical player shot, Rogers Federer took his revenge against Novak Djokovic yesterday by beating him (7-6,7-6, 6-4)

 

By winning this game, Federer achieved:

 

1) His 4 th straight US open (2004-2005-2006 and 2007). It's a new record.

2) 12 th Grand Slam titles (the second after Sampras who has won 14 Grand Slem titles

3) 2,4 millions dollars for just the US open title (poor of him)

 

To see my tennis set

 

Have a great week !

 

Viewed at Long Sault by the water Hoople Bay. Came here quickly after canoeing at Cornwall Canal where we saw and photographed Sun Dog by low sun predicting rain.

SkyFire predicted a decent chance of a colorful sunset on this day before the remnants of Hurricane Rosa arrived, so I decided to check out the Burnham badlands in NW New Mexico. Not as showy or well known as other hoodoo lands in the Bisti and Ah-Shi-Sle-Pah, there was still plenty to see and photograph. Best of all, my pal Colorado Plateau photographer extraordinaire Cecil Whitt & I had the place all to ourselves.

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A panorama consisting of 6 single exposures stitched together. In winter 2013/14 we got snow late, at the end of January, but really a lot of it. In some other parts of Carinthia there is snow 3m high on top of the houses. Some towns were disconnected from the grid for some days, schools were closed and so on. Doesn't sound that funny, but better like this, than green winter. Just my opinion. We here in Radenthein have around 1m of snow in sum till now, forecast predicts snow for next week again!

This Sunday was an exciting day at the flea market! Funnily enough, I predicted that we would find treasures. It was Colleen's last day of sort of summer vacation (meaning she would go back to working both jobs instead of just one). On top of that, we had plans to hang out with our friend, Lisa, in the afternoon. It's always on those busy days that you find cool stuff, but don't have the chance to enjoy it. I just knew we would finally have a fruitful weekend at the flea market on the day we had other plans in the afternoon. Despite the gloomy weather, there were exciting things to be found. The pieces of American Girl clothes were all super cheap--$1 to $2 each. The seller had seen us at another booth nearby looking at doll clothes. When we passed his table, he beckoned us over asking if we collected American Girl clothes. It seriously pays off sometimes to be very open about collecting dolls, because I never would have noticed the AG clothes on his table if he hadn't motioned us over. The coolest thing about these pieces is the fact that we completed two of our outfits. We FINALLY got the diaper and a pair of shoes to go with Billie Jean's "meet" outfit. Colleen also noticed that a pair of the shoes were the ones that went with Bitty Baby's Pretty Pink Outfits (both getups were ironically purchased at the flea market back in 2014). There were a few other AG odds and ends we snagged too, like Samantha's gaiters.

 

In the lower portion of the flea market, down the hill into a somewhat muddy area, we walked by a booth with vintage toys. I studied the table as we passed, but didn't see anything worthwhile. However, on the ground on the right side of the booth I spotted an open vintage case (looked like a hatbox almost) and a cardboard box beside it. At first it just looked like a bunch of figurines from the 60s. But as we started to continue onward, Skooter caught the corner of my eye. Immediately I pounced. It turns out there was another Skipper there too. She was a Twist 'N Turn Waist doll with a mutilated leg. Colleen picked her up too for purchase. The Ideal Toys dolls caught my attention as well. I knew they weren't Tammy, but I couldn't figure out if they were from her family/friend line or were different dolls altogether. When Colleen inquired about the price, the man said he'd unload it all for $20. Normally, with the amount of stuff and condition of it, we wouldn't have paid that much. But with 60s doll items, sometimes a singular dolly will be marked that much (I think Colleen paid $25 for her first Skooter doll at an antique store in a handmade outfit). It turns out that we got Misty, Tammy's friend, and Pepper, her little sister. Additionally, there was this awesome Supergirl included! Ironically, I almost left Todd behind because he was so grotesque. I had been wanting a Todd or Tutti doll since 2011, when we got back into collecting. 60s Barbies were some of the first thing that really excited us in those days. Todd was so foul and covered in goop, I mistook him for a freaky figurine. But something told me not to leave him behind. The moment I held him at home, I lost it when I realized who he was. Plus, he was wearing his original outfit!!! Who doesn't love a doll who needs all that TLC?!! The little doll house furniture will work well for our mini houses we've had since we were kids. It's from the Ideal Toys Petite Princess Furniture line. Many of the pieces were broken beyond repair, but these were the things we could work with. Plus, we found two 60s Barbie clothing items--Ken and Ricky's jackets (I seriously would have died if Ricky had been included...he's in the top ten cutest boy dolls ever list).

 

The two Babysitters Inc Skipper dolls were from the elderly couple we always buy from. I also snagged an Ever After High body donor from them. The poor girl had a missing eye that was sharpied over. But she was still wearing her outfit AND had both hands. It was cheaper buying the donor doll than getting a pair of hands from Mattel's Replacement Part website (this is why it makes more sense to use dolls who are too far gone as body/part donors rather than trying to fix them all).

 

As for the Cabbage Patch boy, he is without a doubt my favorite find. I was feeling the Cabbie Fever on Sunday...so was Colleen. At the flea market there are always sellers who put boxes and containers of random junk (literally) on the ground and on tables. They do not take any of it out, you are meant to dig through the bins. Usually I do a quick once over of these booths since they have boring things (like homeware). But as we finished an aisle, I saw a yarn head in a clear container. Immediately my doll senses tingled...I knew it was something cool. From a distance the hair color reminded me of my 1985 Twins. I tried to not get overly amped, knowing it was probably a very similar doll to one I already had. However, as I neared I noticed his legs looked abnormally long and like a slightly different texture. When I turned this guy over I saw the freckles and the cheaper looking head/hair. Immediately I thought to myself, "This is one of the foreign CPKs. Jesmar perhaps?" Sure enough he sported the Jesmar tag (his outfit is also original--tagged Jesmar too). The poor fella was foul, covered in stains and smelling like a dumpster. His condition alone warranted a rescue. The seller was super nice and only wanted $6 for him. I suppose he could have been cheaper, but since sellers at our flea market want $25 for a CPK doll usually, it was a deal. We named him Picasso, and he was a wonderful addition to our CPK family.

 

Dolls in photo from left to right:

-1984 Cabbage Patch Kids (Jesmar)

-1977 Charlie's Angels Sabrina

-1965 Tutti's Tiny Twin Todd

-1966 Pocketbook Doll Jan

-1967 Super Queen Supergirl

-1965 Tammy's Best Friend Misty

-1965 Tammy's Sister Pepper

-1964 Skipper's Friend Skooter

-1968 Twist 'N Turn Waist Skipper

-2018 Babysitters Inc. "Stroller" Skipper

-2019 Babysitters Inc. "Bedtime" Skipper

Have a great day!

Weather.com predicted cloudy skies on Sunday evening. Good thing I ignored their forecast and decided to shoot anyway. Turns out, the skies were clear enough for a pretty decent sunset, captured from East Boston in the LoPresti Park area. Admittedly, the composition is a bit busy, but I had little else to work with, so here you go.

 

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Bathroom, Kensington Church Street, London W8

22 Kalliope is an M-type (partially known composition) asteroid, the predicted magnitude was 11.04, I found it to be close to that estimate using comparative stars in the view. Kalliope measures about 146 x 89 x 77 miles and also has a satellite names Linus which measures about 17 miles in diameter.

Tech Specs: Sky-Watcher 120ED, Canon 6D, single 60 second exposure at ISO 1250. Image Date: June 4, 2018. Location: The Dark Side Observatory, Weatherly, PA, USA

On night of August 26, 2017, I checked and there are only a little over 1,500 views to go; so this is going to happen sooner than I thought, like maybe August 27, 2017.

 

My thanks to each and every one of you for each and every one of them. Dorothy Delina Porter aka Pixel Packing Mama

 

Delina is pronounced with a long *i* sound if you are saying it out loud in your brain right now. Actually, it is still pronounced that way whether you are or are not saying it out loud in your brain. *grin*

  

"ARTSY sign for reaching 25 Million Views"

My Sister in law (and Now Brother in law)'s Wedding yesterday at House for an art lover - hundreds more photos to come! 73/366

Weather reports predict the so called "Beast From The East" is due to revisit the UK over the next few days, today the 16th of March 2018 I visited Collieston Bay, its the first time I have witnessed the impact unusual weather has had on the area, it really was exhilarating and offered great photo opportunities.

 

Collieston is a small former fishing village on the North Sea coast in Aberdeenshire, Scotland. The village lies just north of the Sands of Forvie Special Protection Area, between Cruden Bay and Newburgh.

 

The earliest recorded history of Collieston is of the arrival of St Ternan, a Columban monk on a mission to convert the local picts to Christianity. There is, however, evidence that people lived here during much earlier times.

 

Collieston was established as a fishing village by the 16th century, and it provides the first safe harbour in over fifteen miles of beachesand dunes stretching north from Aberdeen.

 

Fishing for herring, haddock, whiting and codflourished in the 17th century and 18th century and was the foundation of Collieston's economy. The village became known for 'Collieston Speldings', salted and sun-dried haddock and whiting, a popular delicacy throughout Britain. As drift netting developed during the mid 19th century, the fishing began to decline and the focus of the industry shifted to places like Peterhead because the harbour at Collieston was too small to safely accommodate the larger boats needed.

 

The numerous sea caves in the nearby cliffs, and small coves with shingle beaches provided ideal terrain for smugglers. In the late 18th century it was estimated by the Excise that up to 8000 gallons of foreign spirits were being illegally landed in the area every month. In 1798, the notorious village smuggler, Phillip Kennedy, was killed by a blow from an exciseman's cutlass. His grave and tombstone still stands in the village graveyard.

 

A ship from the Spanish Armada, the Santa Caterina, carrying arms for the Earl of Erroll is said to have sunk just off the rocky point of St Catherine's Dub in 1594. In retaliation for the Earl's involvement in the Catholic plot against him, James VI blew up the Earl's castle which stood on the cliffs, a mile north of Collieston. The Earl went on to rebuild Slains Castle, six miles further up the coast, in 1597.

Collieston is now mainly a commuter village serving Aberdeen, and is largely given over to tourists during the summer months.

This brings us to Sir Doktor Professor Karl Raimund Popper’s attack on historicism. As I said in Chapter 5, this was his most significant insight, but it remains his least known. People who do not really know his work tend to focus on Popperian falsification, which addresses the verification or n...

 

#freeebook #freebook #ebook #book #Pomdy

Editor: taphuong

 

www.pomdy.com/book/the-black-swan/part-two-we-just-cant-p...

Since Woodtick predicted that I was about to unleash a deluge of Milwaukee Road shots, I'd hate to disappoint. In the early '80s, recently shed of its "Pacific Extension", the Road found itself short of power (or at least power that worked.) Trains started to sport CN power on other parts of the railroad, but the trains that connected with DW&P in Duluth were a likely candidate for power pools - or just borrowing when short! Milwaukee Road had a longstanding agreement for trackage rights on the former Northern Pacific "Skally" to Duluth; by the '80s it had become rights on the former NP up to Hinckley where the NP crossed the former Great Northern from Minneapolis to Duluth. By this time the NP was mostly gone from that crossing on to the north, so the through trains used the former GN to complete the trip to the Twin Ports. This route was fairly active with BN trains (most of their through trains would use the GN all the way up from Northtown Yard in Minneapolis) and also the MILW and C&NW trackage rights trains...and then the Soo Line, too. This train is on the BN's Minnesota Division, the Sixth Sub that connected the wye at "Division Street" (and the Milwaukee's "Pigs Eye Yard") with the Wisconsin Division, Second Sub, at White Bear Lake. From there it's the ex-NP route to Hinckley (a.k.a. "the Skally.") The tracks in the foreground belong to the C&NW - the "Omaha" - going to and from Chicago. I think that's "East St.Paul" yard around the curve on the Omaha. I believe that practically all of this, except the Union Pacific that was the Omaha, is gone. Now the CP and the UP use the former GN through Northtown all the way to Superior with their trackage rights trains.

Weather reports predict the so called "Beast From The East" is due to revisit the UK over the next few days, today the 16th of March 2018 I visited Collieston Bay, its the first time I have witnessed the impact unusual weather has had on the area, it really was exhilarating and offered great photo opportunities.

 

Collieston is a small former fishing village on the North Sea coast in Aberdeenshire, Scotland. The village lies just north of the Sands of Forvie Special Protection Area, between Cruden Bay and Newburgh.

 

The earliest recorded history of Collieston is of the arrival of St Ternan, a Columban monk on a mission to convert the local picts to Christianity. There is, however, evidence that people lived here during much earlier times.

 

Collieston was established as a fishing village by the 16th century, and it provides the first safe harbour in over fifteen miles of beachesand dunes stretching north from Aberdeen.

 

Fishing for herring, haddock, whiting and codflourished in the 17th century and 18th century and was the foundation of Collieston's economy. The village became known for 'Collieston Speldings', salted and sun-dried haddock and whiting, a popular delicacy throughout Britain. As drift netting developed during the mid 19th century, the fishing began to decline and the focus of the industry shifted to places like Peterhead because the harbour at Collieston was too small to safely accommodate the larger boats needed.

 

The numerous sea caves in the nearby cliffs, and small coves with shingle beaches provided ideal terrain for smugglers. In the late 18th century it was estimated by the Excise that up to 8000 gallons of foreign spirits were being illegally landed in the area every month. In 1798, the notorious village smuggler, Phillip Kennedy, was killed by a blow from an exciseman's cutlass. His grave and tombstone still stands in the village graveyard.

 

A ship from the Spanish Armada, the Santa Caterina, carrying arms for the Earl of Erroll is said to have sunk just off the rocky point of St Catherine's Dub in 1594. In retaliation for the Earl's involvement in the Catholic plot against him, James VI blew up the Earl's castle which stood on the cliffs, a mile north of Collieston. The Earl went on to rebuild Slains Castle, six miles further up the coast, in 1597.

Collieston is now mainly a commuter village serving Aberdeen, and is largely given over to tourists during the summer months.

One can consider the presentation of this spectacular hardtop coupe as an ultimate afford to gain attention of the audience to persuade them for buying a Packard. The financial position of Packard was terrible in 1956. But it wasn't much of a help.

Richard 'Dick' Teague (Los Angeles, 1923-1991) designed the Predictor. It was built at Carrozzeria Ghia, Torino in Italy on a Clipper platform. In ninety days the Italians managed to get this project ready, just in time for the Chicago Car Show (see photo).

 

The Predictor had all kinds of new automotive features, like tilting headlights, roof doors rolled back when opening the door, lowering back window, swiveling seats, dashboard design which followed the hood profile, a power operated trunk lid, and a wraparound windshield that curved into the roof.

Many car brands copied several novelties: the grille at the 1958 Edsel, the roof line at the 1958 Lincoln Premier, the rear bumper at the 1958 Oldsmobile, opera windows or portholes in the rear pillar at the 1957 Thunderbird, and the headlights at the 1962 Corvette.

 

Only one Predictor was made. It still exists and is on display at the Studebaker National Museum, South Bend, Indiana.

 

6128 cc V8 engine.

Production Packard Predictor: 1956.

 

Image source:

Rob de la Rive Box, Amerikanen uit de jaren '50, Rijswijk, Elmar, 1993.

Original photographer, place and date unknown.

 

Halfweg, July 27, 2024.

 

© 2024 Sander Toonen Halfweg | All Rights Reserved

As predicted by the prophet Zacharie Delaplaya, the Four Surfers of the Apocalypso will soon emerge to sound the death knell of summertime. Splitting the sea foam from atop their mounts, they’ll arrive at great speed to announce to the sun-lovers and terrace dwellers the end of this lovely season. So enjoy the time you have left to knock back a pint and live each day as if it was the last act. Carpe diem!

This little iris is a sure predictor of rain. First the bud swells and then when it opens you can be sure that 24-36 hours later it will rain. Never fails.

Well i hope the weather forecast is right both for fotting Choppers up Peak Forest & Taking my Scooby up those Country roads

As predicted yesterday, Viking Twin Otter msn 915 has had its Japan mark covered up so it can go flying. Sister ship msn 916, which is also in the blue scheme, had pre-delivery mark C-GVVA as well and this is going to sow confusion in the future.

The weatherman is predicting more rain tonight ...It was mostly cloudy today with a few drops of rain ,but seemed to be clearing up this evening with this beautiful sunset ..

Heavens-above.com predicted a pass of the International Space Station that would be visible to the Space Coast. It was lower and dimmer than I would generally chase, but I still went to my favorite spot, the "Cuki," a sailboat in Melbourne Beach, FL that was washed ashore after Hurricane Irma.

 

It was cloudier than expected, and I was a bit disappointed by how undramatic the streak turned out until I later looked at the ground track of the Station. At the time of the left-most section of the streak shown here (over the condos), the Station is over the Gulf of Mexico, well south of New Orleans, roughly 1,000km away. The closest the Station would come was 750km, roughly over the sailboat in the streak, and somewhere over Alabama east of Montgomery. And, as it enters the shadow of the Earth (after emerging from behind the cloud in the right section of the frame), the Station is nearly 1,100 km away, cruising over (roughly) Blacksburg, Virgina.

 

New Orleans, Alabama, and Virginia. And we can see it from Florida. Kinda cool, no?

 

Details:

This is a composite of two 120-second exposures, shot at ISO400 and f6.3 with a Canon 5DIV and a Rokinon 14mm lens. Initial edits done in Lightroom, composite done in Photoshop (while avoiding the temptation to draw in a bolder streak) and edits were done (again) in Lightroom, then Color Efex2 (detail enhancer) and then some noise reduction was applied with Dfine2.

Celebrating its 50th anniversary in 2016, the TV series "Star Trek" has captured the public’s imagination with the signature phrase, "To boldly go where no one has gone before." NASA's Hubble Space Telescope doesn't "boldly go" deep into space, but it is "boldly peering" deeper into the universe than ever before to explore the warping of space and time and uncover some of the farthest objects ever seen.

 

When "Star Trek" was first broadcast in 1966, the largest telescopes on Earth could only see about halfway across the universe - the rest was uncharted territory. But Hubble's powerful vision has carried us into the true "final frontier."

 

This is epitomized in the latest Hubble image released today in time for the new motion picture "Star Trek Beyond." The Hubble image unveils a very cluttered-looking universe filled with galaxies near and far. Some are distorted like a funhouse mirror through a warping-of-space phenomenon first predicted by Einstein a century ago.

 

In the center of the image is the immense galaxy cluster Abell S1063, located 4 billion light-years away, and surrounded by magnified images of galaxies much farther.

 

Thanks to Hubble's exquisite sharpness, the photo unveils the effect of space warping due to gravity. The huge mass of the cluster distorts and magnifies the light from galaxies that lie far behind it due to an effect called gravitational lensing. This phenomenon allows Hubble to see galaxies that would otherwise be too small and faint to observe. This "warp field" makes it possible to get a peek at the very first generation of galaxies. Already, an infant galaxy has been found in the field, as it looked 1 billion years after the big bang.

 

For more information, please visit:

www.nasa.gov/feature/goddard/2016/nasa-s-hubble-looks-to-...

 

Credits: NASA, ESA, and J. Lotz (STScI)

This column is believed to represent the four seasons of the year – one on each side. The images on the closest side show a representation of the rain god – Chac shown with the nose of an elephant. Chac is one of the most frequent images that we saw throughout Chichen Itza.

 

Obviously, rain was extremely important to the Maya culture. I assume this was primarily because the Yucatan peninsula is very hot and they would have been highly dependent on rain for drinking water and agricultural irrigation. On our visit, we have been more concerned with the over-abundance of rain related to hurricane Irma. Either way, it is obvious that predicting the weather has been a chief concern of people for a very long time and we still don’t quite have it figured out.

 

Nikon D7100

Tamron SP 10-24mm F/3.5-4.5 Di II

10mm @ f/10 – 1/800 sec – ISO 400

All rights reserved. Available to license with Getty Images.

 

Tetney , The Psychic White Rabbit, Issues France with a stark warning. They must play well to beat Germany on Friday 4th.

A record-setting early snowfall -- predicted to be only a coating to an inch in the city, but actually bringing about three inches – blanketed the late blooming flowers in my garden. Remarkably, even tender annuals like marigolds, begonias and salvia, as well as roses and hardy chrysanthemums have survived a few nights of freezing temperatures and now even the snow. Sorry for the ‘post-and-run’ today… I hope to start catching up with my comments in a little while. I hope you are having a good weekend!

Predicting the unpredictable....FUN!

The Northern Mockingbird at Fort Mason in San Francisco is now singing non-stop, from before dawn until after dusk. It's the loudest bird in the garden (matching the parrots), and it imitates many other bird species. I can predict some of the other birds at Fort Mason by listening to the Mockingbird. For example, it's been mimicking the Baltimore Oriole that has been there all winter, the Western Grebes that swim in Aquatic Park, and the Caspian Terns that have recently begun to fly over.

Since I am no genetics specialist, I did not feel legitimate about predicting human beings' evolution from a physical point of view. I preferred to imagine it metaphorically.

 

When one observes current society, human greed is extremely obvious. Money leads almost everything. What let me bitter, is the fact this greed is often totally useless: while some money can be obviously useful to live comfortably, accumulating it just to be able to write more "zeros" on a bank account makes not much sense to me. I feel like there's no precise goal to that, except the thrill to possess more and more, to keep stacking things blindly, even if it reaches the point where it becomes destructive. I look at such behavior like a severe addiction.

 

This is such feeling I wanted to share through my image. I chose to depict a dark future, where the new leading animal (obviously evolved from human beings) keeps working towards a goal, without really knowing why. This lack of conscience is symbolized by the hole in the middle of their chests, while they keep feeding the big fat creature that they worship.

www.rollingstone.com/news/story/10432334/was_the_2004_ele...

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Was the 2004 Election Stolen?

Republicans prevented more than 350,000 voters in Ohio from casting ballots or having their votes counted -- enough to have put John Kerry in the White House. BY ROBERT F. KENNEDY JR.

 

Page 1 2 3 4

The complete article, with Web-only citations, follows. For more, see exclusive documents, sources, charts and commentary.

Like many Americans, I spent the evening of the 2004 election watching the returns on television and wondering how the exit polls, which predicted an overwhelming victory for John Kerry, had gotten it so wrong. By midnight, the official tallies showed a decisive lead for George Bush -- and the next day, lacking enough legal evidence to contest the results, Kerry conceded. Republicans derided anyone who expressed doubts about Bush's victory as nut cases in ''tinfoil hats,'' while the national media, with few exceptions, did little to question the validity of the election. The Washington Post immediately dismissed allegations of fraud as ''conspiracy theories,''(1) and The New York Times declared that ''there is no evidence of vote theft or errors on a large scale.''(2)

 

But despite the media blackout, indications continued to emerge that something deeply troubling had taken place in 2004. Nearly half of the 6 million American voters living abroad(3) never received their ballots -- or received them too late to vote(4) -- after the Pentagon unaccountably shut down a state-of-the-art Web site used to file overseas registrations.(5) A consulting firm called Sproul & Associates, which was hired by the Republican National Committee to register voters in six battleground states,(6) was discovered shredding Democratic registrations.(7) In New Mexico, which was decided by 5,988 votes,(8) malfunctioning machines mysteriously failed to properly register a presidential vote on more than 20,000 ballots.(9) Nationwide, according to the federal commission charged with implementing election reforms, as many as 1 million ballots were spoiled by faulty voting equipment -- roughly one for every 100 cast.(10)

 

The reports were especially disturbing in Ohio, the critical battleground state that clinched Bush's victory in the electoral college. Officials there purged tens of thousands of eligible voters from the rolls, neglected to process registration cards generated by Democratic voter drives, shortchanged Democratic precincts when they allocated voting machines and illegally derailed a recount that could have given Kerry the presidency. A precinct in an evangelical church in Miami County recorded an impossibly high turnout of ninety-eight percent, while a polling place in inner-city Cleveland recorded an equally impossible turnout of only seven percent. In Warren County, GOP election officials even invented a nonexistent terrorist threat to bar the media from monitoring the official vote count.(11)

 

Any election, of course, will have anomalies. America's voting system is a messy patchwork of polling rules run mostly by county and city officials. ''We didn't have one election for president in 2004,'' says Robert Pastor, who directs the Center for Democracy and Election Management at American University. ''We didn't have fifty elections. We actually had 13,000 elections run by 13,000 independent, quasi-sovereign counties and municipalities.''

 

But what is most anomalous about the irregularities in 2004 was their decidedly partisan bent: Almost without exception they hurt John Kerry and benefited George Bush. After carefully examining the evidence, I've become convinced that the president's party mounted a massive, coordinated campaign to subvert the will of the people in 2004. Across the country, Republican election officials and party stalwarts employed a wide range of illegal and unethical tactics to fix the election. A review of the available data reveals that in Ohio alone, at least 357,000 voters, the overwhelming majority of them Democratic, were prevented from casting ballots or did not have their votes counted in 2004(12) -- more than enough to shift the results of an election decided by 118,601 votes.(13) (See Ohio's Missing Votes) In what may be the single most astounding fact from the election, one in every four Ohio citizens who registered to vote in 2004 showed up at the polls only to discover that they were not listed on the rolls, thanks to GOP efforts to stem the unprecedented flood of Democrats eager to cast ballots.(14) And that doesn?t even take into account the troubling evidence of outright fraud, which indicates that upwards of 80,000 votes for Kerry were counted instead for Bush. That alone is a swing of more than 160,000 votes -- enough to have put John Kerry in the White House.(15)

 

''It was terrible,'' says Sen. Christopher Dodd, who helped craft reforms in 2002 that were supposed to prevent such electoral abuses. ''People waiting in line for twelve hours to cast their ballots, people not being allowed to vote because they were in the wrong precinct -- it was an outrage. In Ohio, you had a secretary of state who was determined to guarantee a Republican outcome. I'm terribly disheartened.''

 

Indeed, the extent of the GOP's effort to rig the vote shocked even the most experienced observers of American elections. ''Ohio was as dirty an election as America has ever seen,'' Lou Harris, the father of modern political polling, told me. ''You look at the turnout and votes in individual precincts, compared to the historic patterns in those counties, and you can tell where the discrepancies are. They stand out like a sore thumb.''

 

I. The Exit Polls

The first indication that something was gravely amiss on November 2nd, 2004, was the inexplicable discrepancies between exit polls and actual vote counts. Polls in thirty states weren't just off the mark -- they deviated to an extent that cannot be accounted for by their margin of error. In all but four states, the discrepancy favored President Bush.(16)

 

Over the past decades, exit polling has evolved into an exact science. Indeed, among pollsters and statisticians, such surveys are thought to be the most reliable. Unlike pre-election polls, in which voters are asked to predict their own behavior at some point in the future, exit polls ask voters leaving the voting booth to report an action they just executed. The results are exquisitely accurate: Exit polls in Germany, for example, have never missed the mark by more than three-tenths of one percent.(17) ''Exit polls are almost never wrong,'' Dick Morris, a political consultant who has worked for both Republicans and Democrats, noted after the 2004 vote. Such surveys are ''so reliable,'' he added, ''that they are used as guides to the relative honesty of elections in Third World countries.''(18) In 2003, vote tampering revealed by exit polling in the Republic of Georgia forced Eduard Shevardnadze to step down.(19) And in November 2004, exit polling in the Ukraine -- paid for by the Bush administration -- exposed election fraud that denied Viktor Yushchenko the presidency.(20)

 

But that same month, when exit polls revealed disturbing disparities in the U.S. election, the six media organizations that had commissioned the survey treated its very existence as an embarrassment. Instead of treating the discrepancies as a story meriting investigation, the networks scrubbed the offending results from their Web sites and substituted them with ''corrected'' numbers that had been weighted, retroactively, to match the official vote count. Rather than finding fault with the election results, the mainstream media preferred to dismiss the polls as flawed.(21)

 

''The people who ran the exit polling, and all those of us who were their clients, recognized that it was deeply flawed,'' says Tom Brokaw, who served as anchor for NBC News during the 2004 election. ''They were really screwed up -- the old models just don't work anymore. I would not go on the air with them again.''

 

In fact, the exit poll created for the 2004 election was designed to be the most reliable voter survey in history. The six news organizations -- running the ideological gamut from CBS to Fox News -- retained Edison Media Research and Mitofsky International,(22) whose principal, Warren Mitofsky, pioneered the exit poll for CBS in 1967(23) and is widely credited with assuring the credibility of Mexico's elections in 1994.(24) For its nationwide poll, Edison/Mitofsky selected a random subsample of 12,219 voters(25) -- approximately six times larger than those normally used in national polls(26) -- driving the margin of error down to approximately plus or minus one percent.(27)

 

On the evening of the vote, reporters at each of the major networks were briefed by pollsters at 7:54 p.m. Kerry, they were informed, had an insurmountable lead and would win by a rout: at least 309 electoral votes to Bush's 174, with fifty-five too close to call.(28) In London, Prime Minister Tony Blair went to bed contemplating his relationship with President-elect Kerry.(29)

 

As the last polling stations closed on the West Coast, exit polls showed Kerry ahead in ten of eleven battleground states -- including commanding leads in Ohio and Florida -- and winning by a million and a half votes nationally. The exit polls even showed Kerry breathing down Bush's neck in supposed GOP strongholds Virginia and North Carolina.(30) Against these numbers, the statistical likelihood of Bush winning was less than one in 450,000.(31) ''Either the exit polls, by and large, are completely wrong,'' a Fox News analyst declared, ''or George Bush loses.''(32)

 

But as the evening progressed, official tallies began to show implausible disparities -- as much as 9.5 percent -- with the exit polls. In ten of the eleven battleground states, the tallied margins departed from what the polls had predicted. In every case, the shift favored Bush. Based on exit polls, CNN had predicted Kerry defeating Bush in Ohio by a margin of 4.2 percentage points. Instead, election results showed Bush winning the state by 2.5 percent. Bush also tallied 6.5 percent more than the polls had predicted in Pennsylvania, and 4.9 percent more in Florida.(33)

 

According to Steven F. Freeman, a visiting scholar at the University of Pennsylvania who specializes in research methodology, the odds against all three of those shifts occurring in concert are one in 660,000. ''As much as we can say in sound science that something is impossible,'' he says, ''it is impossible that the discrepancies between predicted and actual vote count in the three critical battleground states of the 2004 election could have been due to chance or random error.'' (See The Tale of the Exit Polls)

 

Puzzled by the discrepancies, Freeman laboriously examined the raw polling data released by Edison/Mitofsky in January 2005. ''I'm not even political -- I despise the Democrats,'' he says. ''I'm a survey expert. I got into this because I was mystified about how the exit polls could have been so wrong.'' In his forthcoming book, Was the 2004 Presidential Election Stolen? Exit Polls, Election Fraud, and the Official Count, Freeman lays out a statistical analysis of the polls that is deeply troubling.

 

In its official postmortem report issued two months after the election, Edison/Mitofsky was unable to identify any flaw in its methodology -- so the pollsters, in essence, invented one for the electorate. According to Mitofsky, Bush partisans were simply disinclined to talk to exit pollsters on November 2nd(34) -- displaying a heretofore unknown and undocumented aversion that skewed the polls in Kerry's favor by a margin of 6.5 percent nationwide.(35)

 

Industry peers didn't buy it. John Zogby, one of the nation's leading pollsters, told me that Mitofsky's ''reluctant responder'' hypothesis is ''preposterous.''(36) Even Mitofsky, in his official report, underscored the hollowness of his theory: ''It is difficult to pinpoint precisely the reasons that, in general, Kerry voters were more likely to participate in the exit polls than Bush voters.''(37)

 

Now, thanks to careful examination of Mitofsky's own data by Freeman and a team of eight researchers, we can say conclusively that the theory is dead wrong. In fact it was Democrats, not Republicans, who were more disinclined to answer pollsters' questions on Election Day. In Bush strongholds, Freeman and the other researchers found that fifty-six percent of voters completed the exit survey -- compared to only fifty-three percent in Kerry strongholds.(38) ''The data presented to support the claim not only fails to substantiate it,'' observes Freeman, ''but actually contradicts it.''

 

What's more, Freeman found, the greatest disparities between exit polls and the official vote count came in Republican strongholds. In precincts where Bush received at least eighty percent of the vote, the exit polls were off by an average of ten percent. By contrast, in precincts where Kerry dominated by eighty percent or more, the exit polls were accurate to within three tenths of one percent -- a pattern that suggests Republican election officials stuffed the ballot box in Bush country.(39)

 

''When you look at the numbers, there is a tremendous amount of data that supports the supposition of election fraud,'' concludes Freeman. ''The discrepancies are higher in battleground states, higher where there were Republican governors, higher in states with greater proportions of African-American communities and higher in states where there were the most Election Day complaints. All these are strong indicators of fraud -- and yet this supposition has been utterly ignored by the press and, oddly, by the Democratic Party.''

 

The evidence is especially strong in Ohio. In January, a team of mathematicians from the National Election Data Archive, a nonpartisan watchdog group, compared the state's exit polls against the certified vote count in each of the forty-nine precincts polled by Edison/Mitofsky. In twenty-two of those precincts -- nearly half of those polled -- they discovered results that differed widely from the official tally. Once again -- against all odds -- the widespread discrepancies were stacked massively in Bush's favor: In only two of the suspect twenty-two precincts did the disparity benefit Kerry. The wildest discrepancy came from the precinct Mitofsky numbered ''27,'' in order to protect the anonymity of those surveyed. According to the exit poll, Kerry should have received sixty-seven percent of the vote in this precinct. Yet the certified tally gave him only thirty-eight percent. The statistical odds against such a variance are just shy of one in 3 billion.(40)

 

Such results, according to the archive, provide ''virtually irrefutable evidence of vote miscount.'' The discrepancies, the experts add, ''are consistent with the hypothesis that Kerry would have won Ohio's electoral votes if Ohio's official vote counts had accurately reflected voter intent.''(41) According to Ron Baiman, vice president of the archive and a public policy analyst at Loyola University in Chicago, ''No rigorous statistical explanation'' can explain the ''completely nonrandom'' disparities that almost uniformly benefited Bush. The final results, he adds, are ''completely consistent with election fraud -- specifically vote shifting.''

 

II. The Partisan Official

No state was more important in the 2004 election than Ohio. The state has been key to every Republican presidential victory since Abraham Lincoln's, and both parties overwhelmed the state with television ads, field organizers and volunteers in an effort to register new voters and energize old ones. Bush and Kerry traveled to Ohio a total of forty-nine times during the campaign -- more than to any other state.(42)

 

But in the battle for Ohio, Republicans had a distinct advantage: The man in charge of the counting was Kenneth Blackwell, the co-chair of President Bush's re-election committee.(43) As Ohio's secretary of state, Blackwell had broad powers to interpret and implement state and federal election laws -- setting standards for everything from the processing of voter registration to the conduct of official recounts.(44) And as Bush's re-election chair in Ohio, he had a powerful motivation to rig the rules for his candidate. Blackwell, in fact, served as the ''principal electoral system adviser'' for Bush during the 2000 recount in Florida,(45) where he witnessed firsthand the success of his counterpart Katherine Harris, the Florida secretary of state who co-chaired Bush's campaign there.(46)

 

Blackwell -- now the Republican candidate for governor of Ohio(47) -- is well-known in the state as a fierce partisan eager to rise in the GOP. An outspoken leader of Ohio's right-wing fundamentalists, he opposes abortion even in cases of rape(48) and was the chief cheerleader for the anti-gay-marriage amendment that Republicans employed to spark turnout in rural counties(49). He has openly denounced Kerry as ''an unapologetic liberal Democrat,''(50) and during the 2004 election he used his official powers to disenfranchise hundreds of thousands of Ohio citizens in Democratic strongholds. In a ruling issued two weeks before the election, a federal judge rebuked Blackwell for seeking to ''accomplish the same result in Ohio in 2004 that occurred in Florida in 2000.''(51)

 

''The secretary of state is supposed to administer elections -- not throw them,'' says Rep. Dennis Kucinich, a Democrat from Cleveland who has dealt with Blackwell for years. ''The election in Ohio in 2004 stands out as an example of how, under color of law, a state election official can frustrate the exercise of the right to vote.''

 

The most extensive investigation of what happened in Ohio was conducted by Rep. John Conyers, the ranking Democrat on the House Judiciary Committee.(52) Frustrated by his party's failure to follow up on the widespread evidence of voter intimidation and fraud, Conyers and the committee's minority staff held public hearings in Ohio, where they looked into more than 50,000 complaints from voters.(53) In January 2005, Conyers issued a detailed report that outlined ''massive and unprecedented voter irregularities and anomalies in Ohio.'' The problems, the report concludes, were ''caused by intentional misconduct and illegal behavior, much of it involving Secretary of State J. Kenneth Blackwell.''(54)

 

''Blackwell made Katherine Harris look like a cupcake,'' Conyers told me. ''He saw his role as limiting the participation of Democratic voters. We had hearings in Columbus for two days. We could have stayed two weeks, the level of fury was so high. Thousands of people wanted to testify. Nothing like this had ever happened to them before.''

 

When ROLLING STONE confronted Blackwell about his overtly partisan attempts to subvert the election, he dismissed any such claim as ''silly on its face.'' Ohio, he insisted in a telephone interview, set a ''gold standard'' for electoral fairness. In fact, his campaign to subvert the will of the voters had begun long before Election Day. Instead of welcoming the avalanche of citizen involvement sparked by the campaign, Blackwell permitted election officials in Cleveland, Cincinnati and Toledo to conduct a massive purge of their voter rolls, summarily expunging the names of more than 300,000 voters who had failed to cast ballots in the previous two national elections.(55) In Cleveland, which went five-to-one for Kerry, nearly one in four voters were wiped from the rolls between 2000 and 2004.(56)

 

There were legitimate reasons to clean up voting lists: Many of the names undoubtedly belonged to people who had moved or died. But thousands more were duly registered voters who were deprived of their constitutional right to vote -- often without any notification -- simply because they had decided not to go to the polls in prior elections.(57) In Cleveland's precinct 6C, where more than half the voters on the rolls were deleted,(58) turnout was only 7.1 percent(59) -- the lowest in the state.

 

According to the Conyers report, improper purging ''likely disenfranchised tens of thousands of voters statewide.''(60) If only one in ten of the 300,000 purged voters showed up on Election Day -- a conservative estimate, according to election scholars -- that is 30,000 citizens who were unfairly denied the opportunity to cast ballots.

 

III. The Strike Force

In the months leading up to the election, Ohio was in the midst of the biggest registration drive in its history. Tens of thousands of volunteers and paid political operatives from both parties canvassed the state, racing to register new voters in advance of the October 4th deadline. To those on the ground, it was clear that Democrats were outpacing their Republican counterparts: A New York Times analysis before the election found that new registrations in traditional Democratic strongholds were up 250 percent, compared to only twenty-five percent in Republican-leaning counties.(61) ''The Democrats have been beating the pants off us in the air and on the ground,'' a GOP county official in Columbus confessed to The Washington Times.(62)

 

To stem the tide of new registrations, the Republican National Committee and the Ohio Republican Party attempted to knock tens of thousands of predominantly minority and urban voters off the rolls through illegal mailings known in electioneering jargon as ''caging.'' During the Eighties, after the GOP used such mailings to disenfranchise nearly 76,000 black voters in New Jersey and Louisiana, it was forced to sign two separate court orders agreeing to abstain from caging.(63) But during the summer of 2004, the GOP targeted minority voters in Ohio by zip code, sending registered letters to more than 200,000 newly registered voters(64) in sixty-five counties.(65) On October 22nd, a mere eleven days before the election, Ohio Republican Party Chairman Bob Bennett -- who also chairs the board of elections in Cuyahoga County -- sought to invalidate the registrations of 35,427 voters who had refused to sign for the letters or whose mail came back as undeliverable.(66) Almost half of the challenged voters were from Democratic strongholds in and around Cleveland.(67)

 

There were plenty of valid reasons that voters had failed to respond to the mailings: The list included people who couldn't sign for the letters because they were serving in the U.S. military, college students whose school and home addresses differed,(68) and more than 1,000 homeless people who had no permanent mailing address.(69) But the undeliverable mail, Bennett claimed, proved the new registrations were fraudulent.

 

By law, each voter was supposed to receive a hearing before being stricken from the rolls.(70) Instead, in the week before the election, kangaroo courts were rapidly set up across the state at Blackwell's direction that would inevitably disenfranchise thousands of voters at a time(71) -- a process that one Democratic election official in Toledo likened to an ''inquisition.''(72) Not that anyone was given a chance to actually show up and defend their right to vote: Notices to challenged voters were not only sent out impossibly late in the process, they were mailed to the very addresses that the Republicans contended were faulty.(73) Adding to the atmosphere of intimidation, sheriff's detectives in Sandusky County were dispatched to the homes of challenged voters to investigate the GOP's claims of fraud.(74)

We were looking forward to a good hike with mild temperatures and little wind. The winds were much higher than predicted, but manageable. There was much less snow than we would have thought, considering we've above average snowfalls for this year. While the wind was annoying, the fact that wet snow would often clump to our boots was very frustrating... With all the ups and downs, we gained just over 800 m's on this very undulating 10.3 km return distance hike, but took 6 and a half hours to complete. The loveliest surprise was herd of Rocky Mountain Sheep near the true summit.

As predicted - I went bird hunting but I found so much more than birds this weekend. Great weekend to be outdoors in Texas even though the sun got really warm.

 

Just a bit more info on the caracara - it is a member of the falcon family. It is thought that it was the original bird depicted on the flag of Mexico although that bird is now a golden eagle. Very non-falcon like in its behaviour, it tends to scavenge as well as hunt for its prey although I've seen a a pair of these birds tormenting a whilte pelican on East Beach at Galveston. They literally drove the white pelican off its nest and away. I guess you might say they don't play nice.

St David's Cathedral (in Welsh Eglwys Gadeiriol Tyddewi) which is situated in St Davids (the smallest City in Britain) in the county of Pembrokeshire, on the most westerly point of Wales.

 

The Cathedral stands on the site of a 6th-century monastery founded by Dewi (David), a Celtic Christian monk, who later became St David the Patron Saint of Wales. Due to the relics of St David, the cathedral was a major pilgrimage destination throughout the Middle Ages.

 

In the 6th Century St David was reputedly born on a cliff top on the South-West Wales coast during a fierce storm. The site of David’s birth is marked by the ruin of a tiny ancient chapel close to a holy well and the more recent 18th century chapel dedicated to his mother Non can still be seen near St. David’s Cathedral.

 

The Celtic saint soon became famous for his learned preaching, devotion to God, and extreme asceticism (he ate only bread and herbs, drank only water, and regularly stood in cold water for long periods). He was nicknamed Dewi Ddyfrwr, David the Water Drinker.

 

Many legends have circulated about David, including one alleging that King Arthur was his uncle and that among the "prophecies of Merlin" was a prediction that St David would found a bishopric in Wales. In another legend, St. Gildas foretold David's birth when a pregnant woman came into the church as he was preaching. He was struck dumb, and on regaining his power of speech, predicted that she would give birth to a son "with a greater proportion of the divine spirit than has ever fallen to the share of a preacher."

 

Life in the monastic community that formed under David's leadership was a simple one of prayer, study, and hard labor. Soon a bishopric was established at the site (according to tradition, David was the first bishop), making the monastic church a cathedral. In the centuries that followed, St. David's Cathedral suffered more than a dozen attacks by Vikings and other marauders. Bishops of St. David's were killed in 999 and 1080.

 

In 1081, William the Conqueror visited St Davids to pray and, probably, to explore its strategic benefits due to its proximity to Ireland. The cathedral was safe under Norman rule, but at the cost of its original Welsh character. The Normans regarded their own form of Christianity as superior to the Celtic way, and soon set out to reform it. This was probably the motivation behind the Latin Life of David written by a bishop's son in 1090, which reports that David visited Jerusalem and was consecrated bishop by the patriarc.

 

Information Sources:

www.historic-uk.com/HistoryMagazine/DestinationsUK/St-Dav... www.britainexpress.com/attractions.htm?attraction=530

 

Predicting your call on the extra board can be a bit like long division, needlessly complicated and never really sure you got it right... until the phone rings. Today I thought I had it all dialed in, a phosphate train off the CSX coming north on the Superior Sub was showing ordered for 1230 out of Pokegama with no north pools available for several hours, got it. Just before that call was expected to come in, the phone rang. CN Crew Caller... well shit. “Mr Hennessy are you qualified on the T-Bird?” Yes. Yes I am. So off to Keenan I went. Left a little early in hopes of catching some iron ore action, timing was great as I paced a northbound limestone train from Alborn up to the range, unfortunately the sun was shit for northbound moves. Coming up to Fairlane I spied a load of pellets ready to head south, hedging my bets that he would get the light clearing the limestone train I parked. Sure enough the limestone blazed past and the pellet loader was headed to the docks in Duluth. These standard cab dash 8’s hold a special place in my heart as I made my first solo run as an engineer in one (CN 2019) on a Q119 several years prior. Most fans up here loath the toasters and covet the sd40’s, a sentiment I certainly understand but anywhere else in the country finding standard cab dash 8’a leading trains in 2021 would be constitute a miracle from christ himself... on the range, just another reason not to take the lens cap off. I should get out more often to shoot these dinosaurs, but CN is very good at finding ways to occupy my time and my daughters take up the rest. These old GE’s may have another couple years left in them but the kids only stay 5 and 3 for another couple months. Priorities... It does make me appreciate the rare moments trackside that I have however!

 

A vibrant sunrise was predicted to the west and it had been some time since I photographed the Golden Gate Bridge, so I set my alarm for 4am and drove to Battery Spencer from Sacramento in time for sunrise. www.optimalfocusphotography.com

Michel de Nostredame, dit Nostradamus, né le 14 décembre 1503 à Saint-Rémy-de-Provence, et mort le 2 juillet 1566 à Salon-de-Provence, est un apothicaire1 français (on dirait en français moderne : pharmacien2).

 

Selon bien des sources3, il aurait également été médecin, bien que son expulsion de la faculté de médecine de Montpellier4 témoigne qu’il n'était pas possible d’être les deux à la fois5.

 

Pratiquant l'astrologie comme tous ses confrères à l'époque de la Renaissance, il est surtout connu pour ses prédictions sur la marche du monde.

Il est né de Jaume6 de Nostredame et Reynière (ou Renée) de Saint-Rémy le 14 décembre 15037. Jaume était l'aîné des six (certains disent dix-huit) enfants du couple Pierre de Nostredame et Blanche de Sainte-Marie.

Le nom des Nostredame vient de son grand-père juif, Guy de Gassonet (fils d'Arnauton de Velorges), qui choisit le nom de Pierre de Nostredame lors de sa conversion au catholicisme, probablement vers 14558. Selon les archives d'Avignon, et selon les archives de Carpentras qui parlent souvent de juifs des autres régions, il est suggéré que l'origine du nom Nostredame fut imposée9 par le cardinal-archevêque d'Arles, Pierre de Foix. Le grand-père de Nostredame, Pierre de Nostredame, était si convaincu de sa foi qu'il a répudié sa femme d'alors (Benastruge Gassonet) qui ne voulait pas quitter le judaïsme. Le curieux « démariage » fut prononcé à Orange le 14 juin 1463 (ce qui lui a permis finalement d'épouser Blanche).C'est son bisaïeul maternel, Jean de Saint-Rémy, ancien médecin et trésorier de Saint-Rémy, qui lui aurait transmis en 1506 les rudiments des mathématiques et des lettres. Mais ceci est douteux, vu que la trace notariée (Archives dep. des Bouches du Rhône B. 2.607) de ce vieux personnage disparaît en 1504.Il part très jeune à Avignon pour y obtenir son diplôme de bachelier ès arts. On le disait doué d'une mémoire presque divine, d'un caractère enjoué, plaisant, peut-être un peu moqueur « laetus, facetus estque mordax »10. Ses camarades l'auraient appelé « le jeune astrologue », parce « qu'il leur signalait et leur expliquait les phénomènes célestes », mystérieux alors pour beaucoup : les étoiles filantes, les météores, les astres, les brouillards, etc. Il dut apprendre aussi la grammaire, la rhétorique et la philosophie. Mais il doit quitter l'université après un an seulement, et donc sans diplôme, à cause de l'arrivée de la peste (fin 1520). Neuf ans plus tard (1529), ayant cependant pratiqué comme apothicaire (profession non diplômée), il s'inscrit à la Faculté de Montpellier pour essayer d'y gagner son doctorat en médecine. Il se fait connaître grâce aux remèdes qu'il a mis au point en tant qu'apothicaire. Mais il est bientôt expulsé pour avoir exercé ce métier « manuel » interdit par les statuts de la faculté [voir site Benazra Espace Nostradamus]. Son inscription de 1529 et sa radiation sont les seules traces de son passage à Montpellier, et on ne connaît pas de document attestant qu'il ait été docteur d'une autre université. Mais, sans être affirmatifs, la plupart des érudits du vingtième siècle pensent qu'il n'est pas impossible que l'expulsion de Nostredame ait été temporaire et qu'il soit devenu quand même diplômé de l'université de Montpellier (comme le prétendaient aussi, en ajoutant des détails supplémentaires peu croyables, certains commentateurs très tardifs comme Guynaud et Astruc), bien qu'il lui ait manqué le premier diplôme nécessaire pour accéder au doctorat, car les noms de plusieurs des diplômés connus de cette université sont absents, eux aussi, de ses registres11 — à moins que ceux-ci n'en aient pas été de vrais diplômés non plus (le phénomène du « faux docteur » étant très connu à l'époque).

 

Vers 1533, il s'établit à Agen12, où il pratique la médecine de soins à domicile. Il s'y lie d'amitié avec Jules César Scaliger. Cet Italien, installé à Toulouse, érudit de la Renaissance, est « un personnage incomparable, sinon à un Plutarque » selon Nostradamus ; il écrit sur tout. Impertinent, il s'attaque à tout le monde, s'intéresse à la botanique et fabrique des pommades et des onguents. Mais le jeune « imposteur » inquiète les autorités religieuses par ses idées un peu trop progressistes pour l'époque.

 

La durée précise de son séjour à Agen est inconnue ; peut-être trois ans, peut-être cinq ans. Les points de repère manquent et l'on ne peut offrir que des dates élastiques. Vers 153413 Nostredame s'y choisit une femme dont on ne sait même pas le nom14, qui lui aurait donné deux enfants : un garçon et une fille. L'épouse et les deux enfants moururent, très rapidement semble-t-il, à l'occasion de quelque épidémie, la peste vraisemblablement.

 

D'après certains commentateurs catholiques des Prophéties - Barrere, l'abbé Torne-Chavigny notamment - Nostredame aurait dit en 1534 à un « frère » qui coulait une statue de Notre-Dame dans un moule d'étain qu'en faisant de pareilles images il ne faisait que des diableries. D'aucuns pensent que ses relations avec un certain Philibert Sarrazin, mécréant de l'époque, de la région d'Agen, avaient rendu Nostredame plutôt suspect à la Sainte Inquisition15. Celle-ci l'aurait même invité à se présenter devant son tribunal de Toulouse pour « y être jugé du crime d'hérésie ; mais il se garda bien de répondre à cette citation »16.

 

Après la mort de sa première femme, Nostredame se serait remis à voyager. On l'aurait trouvé à Bordeaux, vers l'an 1539. Les commentateurs tardifs Moura et Louvet se le représentent en la compagnie de savants renommés de l'époque et du cru : l'apothicaire Léonard Baudon, Johannes Tarraga, Carolus Seninus et Jean Treilles, avocat.

 

Nostredame accomplit de 1540 à 1545 un tour de France qui l'amène à rencontrer de nombreuses personnalités, savants et médecins. La légende signale le passage du futur prophète à Bar-le-Duc. Nostredame y aurait soigné, d'après Étienne Jaubert17, plusieurs personnes et notamment une célèbre (?) Mademoiselle Terry qui l'aurait souvent entendu « exhorter les catholiques à tenir ferme contre les Luthériens et à ne permettre qu'ils entrassent dans la ville»18.

 

Une tradition très douteuse affirme qu'il a séjourné un temps à l'abbaye d'Orval, qui dépendait de l'Ordre de Cîteaux, située alors au diocèse de Trêves, à deux lieues de l'actuelle sous-préfecture de Montmédy, un séjour que Pagliani, après plusieurs autres, date de 154319. On ne sait s'il faut y ajouter foi, même si, avec Torne-Chavigny et Napolêon lui-même, beaucoup de gens lui attribuent les fameuses prophéties d'Orval, Prévisions d'un solitaire, ainsi que celles d'un certain Olivarius. On les aurait 'trouvées' à l'abbaye d'Orval en 1792, date approximative de leur style même. La première (de style tardif, elle aussi) serait datée de 1542, antérieure donc de treize ans, comme on le verra plus loin, à la préface des premières Centuries. Mais il semble plus probable que toutes les deux aient été composées au XIXe siècle à la gloire de Napoléon20.

 

Ici se termine le cycle de pérégrinations de Nostredame qui l'a mené en somme, après être rayé de Montpellier, du Sud-Ouest au Nord-Est de la France. Nostredame atteint la quarantaine (1543) et commence une seconde phase de déplacements qui va le rapprocher de la Provence et le pousser vers l'Italie, terre bénie de tous ceux qui connurent à son époque l'ivresse de la Renaissance.

 

Les premières étapes de ce périple sont probablement Vienne, puis « Valence des Allobroges », dont parle Nostradamus dans son Traité des fardemens et confitures à propos des célébrités qu'il s'honora d'y avoir rencontrées : « A Vienne, je vis d'aucuns personnages dignes d'une supprême collaudation ; dont l'un estoit Hieronymus, homme digne de louange, et Franciscus Marins, jeune homme d'une expectative de bonne foy. Devers nous, ne avons que Francisons Valeriola pour sa singulière humanité, pour son sçavoir prompt et mémoire ténacissime... Je ne sçays si le soleil, à trente lieues à la ronde, voit ung homme plus plein de sçavoir que luy »21.

 

En 1544, Nostredame aurait eu l'occasion d'étudier la peste à Marseille22 sous la direction, a-t-il dit, d'un « autre Hippocrate, le médecin Louis Serres »23. Puis, il est « appelé par ceux d'Aix en corps de communauté pour venir dans leur ville traiter les malades de la contagion dont elle est affligée. C'était en l'année mil cinq cent quarante six »24.

 

On le voit certainement à Lyon en 1547 où il s'oppose au médecin lyonnais Philibert Sarrazin25, à Vienne, Valence, Marseille, Aix-en-Provence et, enfin, à Arles, où il finit par s'établir. Là, il met au point un médicament à base de plantes, capable, selon lui, de prévenir la peste. En 1546, il l'expérimente à Aix lors d'une terrible épidémie : son remède semble efficace comme prophylactique, mais il écrira lui-même plus tard que « les seignées, les medicaments cordiaux, catartiques, ne autres n'avoyent non plus d'efficace que rien. » (Traité des fardemens et confitures, Lyon, 1555, p. 52) Malgré ce succès douteux, Nostredame est appelé sur les lieux où des épidémies sont signalées. À la même époque, il commence à publier des almanachs qui mêlent des prévisions météorologiques, des conseils médicaux et des recettes de beauté par les plantes. Il étudie également les astres.

La Maison de Nostradamus à Salon-de-Provence.

 

Le ­11 novembre 1547, il épouse en secondes noces Anne Ponsard, une jeune veuve de Salon-de-Provence, alors appelé Salon-de-Craux. Le couple occupe la maison qui abrite aujourd'hui le Musée Nostradamus. Il aura six enfants, trois filles et trois garçons ; l'aîné, César, deviendra consul de Salon, historien, biographe de son père, peintre et poète.

 

Nostredame prend le temps de voyager en Italie, de 1547 à 1549. C'est d'ailleurs en 1549 qu'il rencontre à Milan un spécialiste en alchimie végétale, qui lui fait découvrir les vertus des confitures qui guérissent. Il expérimente des traitements à base de ces confitures végétales et, de retour en France, il publie en 1552 son Traité des confitures et fardements.

 

En 1550, il rédige son premier « almanach » populaire – une collection de prédictions dites astrologiques pour l’année, incorporant un calendrier26 et d’autres informations en style énigmatique et polyglotte qui devait se montrer assez difficile pour les éditeurs, à en juger par les nombreuses coquilles (où certains voient le signe que l'auteur était dyslexique). Dès cette date, Michel de Nostredame signe ses écrits du nom de "Nostradamus". Ce nom n'est pas l'exacte transcription latine de 'Nostredame', qui serait plutôt Domina nostra ou Nostra domina. En latin correct, ‘Nostradamus’ pourrait signifier : « Nous donnons (damus) les choses qui sont nôtres (nostra) » ou « Nous donnons (damus) les panacées » (nostrum, mis au pluriel), mais il est également permis d'y voir un travestissement macaronique (et très heureux) de 'Nostredame'.

 

En 1555, installé à Salon-de-Provence, il publie des prédictions perpétuelles (et donc en théorie, selon l'usage de l'époque, cycliques)27 dans un ouvrage de plus grande envergure et presque sans dates ciblées, publié par l’imprimeur lyonnais Macé (Matthieu) Bonhomme. Ce sont les Prophéties, l'ouvrage qui fait l'essentiel de sa gloire auprès de la postérité.

source Wikipédia

It was predicted the moon will turn red due to the moon passed through the Earth's shadow (midnight 10 Dec 2011). La Perouse, Sydney.

 

See where this picture was taken. [?]

Another one from Saturday morning. Looking south, was were all the colour was. Has been very nice having a bit of clouds around instead of just the clear blue sky that we have had for so long.

 

Decided to get out Saturday morning, hoping the clouds would still be around. I was not dissapointed, a nice little storm was approaching the coast line - but were able to get a few shots off before the clouds dumped their payload. These were the last two shots of the day. Got drenched running back to the car, but never mind, the clouds are back!

 

After I posted this, I realised that there are actually some clouds called Morning Glory - these are not it.

 

According to Wikipedia

The Morning Glory cloud is a rare meteorological phenomenon occasionally observed in different locations around the world. Southern part of Northern Australia's Gulf of Carpentaria is the only known location in world where it can be predicted and observed on a more or less regular basis. The settlement of Burketown attracts glider pilots intent on riding this phenomenon. (see Burketown, Queensland#Climate)

 

Description

Morning Glory clouds most often can be observed in Burketown in September - mid November, when the chance to see it early in the morning is approximately 40%[1].

 

A Morning Glory cloud is a roll cloud that can be up to 1000 kilometres long, 1 to 2 kilometres high, often only 100 - 200 m above the ground and can move at speeds up to 60 kilometres per hour. Sometimes there comes just one cloud, sometimes there are up to eight consecutive roll clouds.

 

The Morning Glory is often accompanied by sudden wind squalls, intense low-level wind shear, a rapid increase in the vertical displacement of air parcels, and a sharp pressure jump at the surface. In the front of the cloud, there is strong vertical motion that transports air up through the cloud and creates the rolling appearance, while the air in the middle and rear of the cloud becomes turbulent and sinks.

 

The cloud can also be described as a solitary wave or a soliton, which is a wave that has a single crest and moves without changing speed or shape.

 

Causes

Despite being studied extensively, the Morning Glory cloud is not clearly understood.

 

Regardless of the complexity behind the nature of this atmospheric phenomenon, some conclusions have been made about its causes. Through research, one of the main causes of most Morning Glory occurrences is due to the mesoscale circulations associated with sea breezes that develop over the peninsula and the gulf. On the large scale, Morning Glories are usually associated with frontal systems crossing central Australia and high pressure in northern Australia. Locals have noted that the Morning Glory is likely to occur when the humidity in the area is high, which provides moisture for the cloud to form, and when strong sea breezes have blown the preceding day.

 

Could actually be an interesting phenomena to experience. :-)

 

Two exposure blend

f4

ISO100

1.6 and 0.5 seconds

0.90ND Hitech Reverse Grad Filter (3 stop)

Dorotheum

Holga 120CFN, Fomapan 100 film, google predictive search