The Way the Sunshine Falls
Earth Day 2016
Other Technologically Advanced Worlds
'There is a point of view among astronomical researchers that is generally referred to as the Principle of Mediocrity. ...If the Sun and its retinue of worlds is only one system among many, then many other systems will be like ours: home to life. Indeed, to the extent that this is true, we should be prepared for the possibility that, even in the Milky Way galaxy, billions of planets may be carpeted by the dirty, nasty business known as life.'
Seth Shostak
-------------------
Like a lot of people I find it's always fun to speculate about the possibilities of technologically advanced alien civilizations existing in the Universe. In 1961 astronomer Frank Drake created an equation to estimate the number of such civilisations existing in our own galaxy with which communication might be possible (i.e. which are on our current / past light cone).
Each variable in the equation is a vital factor in the development of such civilisations. The Drake Equation has been refined over the decades to include, for example, the ability of a technological civilisation to survive an alien attack.
en.wikipedia.org/wiki/Drake_equation
There are two main arguments concerning the possibilities of complex biological life such as multicellular organisms (subsequently human intelligence on Earth) existing in the Universe at large. Those same arguments are concerned with the potential existence of technological civilisations capable of interstellar communication.
One side argues that the Universe is teeming with advanced technological civilisations (Frank Drake and Carl Sagan for example), the other that such civilisations are an improbable phenomenon. The Rare Earth hypothesis proposed by Peter Ward argues the latter.
We do know that one of the crucial factors in the development of multicellular biological life on Earth was the availability of stable sunshine for the two billion year period it took for slime and single-cell bacteria to evolve into multi-cellular life (one cell swallowed another and the two began working together). However, before this could happen a vast number of improbable variables and events had to exist and occur which, on the face of it, might or might not lend weight to the Rare Earth hypothesis that our planet and its complex lifeforms are the result of a one-in-a-galaxy run of good luck.
Such as:
The right location in the right kind of galaxy.
Orbiting at the right distance from the right type of star.
The right arrangement of planets (It has been argued that Jupiter with its enormous gravitational pull has, over billions of years, reeled in vast quantities of asteroids and other objects that might otherwise have collided with Earth).
A continuously stable orbit.
A terrestrial planet of the right size with plate tectonics.
A large moon (The giant impact theory hypothesizes that the Moon resulted from the impact of a Mars-sized body, Theia, with the very young Earth (approximately 4.5 billion years ago, in the Hadean eon - about 20 to 100 million years after the solar system coalesced). This giant impact, while providing a large moon and important local gravitational pull, gave the Earth its axial tilt and velocity of rotation, vital in creating stable seasons, predictable days and predictable tides.)
One or more evolutionary triggers for complex life.
The right time in evolution (avoiding mass extinction events: extreme climatic variations, super volcanoes or large meteorite/asteroid impacts).
(I'm adding that the random destruction of all non-avian dinosaurs 66 million years ago on Earth by an asteroid - the Chicxulub impact at the Cretaceous–Paleogene boundary on the Yucatán peninsula in Mexico - opened up the planet to mammals, smart creatures who got ever smarter very fast leading to Homo sapiens and our technological civilisation. What if that asteroid had not hit Earth? Perhaps the emergence of a technologically advanced dinosaur civilisation?)
Many argue that only some, or none, of the above conditions are necessary for the evolution of complex biological life and that we are restricting our estimates of the existence of complex life and subsequent technological alien civilizations in the Universe by our sheer lack of imagination.
We might also bear in mind the words of Seth Shostak when speculating about the possibilities of technological alien civilizations existing in the Universe:
'Humans have existed only for the last 0.001 percent of cosmic time. All of which says that - unless the Homo sapiens brain is the one-and-only instance of cogitating machinery - nearly all the intelligence that's out there is beyond our level. And that intelligence is more than just a little bit beyond.'
And finally, the Fermi paradox or "Where is everybody?"
Reasons:
Few intelligent civilizations ever arise.
Intelligent civilizations exist, but we see no evidence (civilizations are too far apart, it is too expensive to spread throughout the galaxy, civilizations broadcast signals for only a brief period of time, it is dangerous to communicate, and many others...).
The lifetime of intelligent civilizations is short (it is the nature of intelligent life to destroy itself, it is the nature of intelligent life to destroy others, they tend to experience a technological singularity, and others...).
It goes without saying that, aside from Earth, we have yet to prove the existence of life, past or present, in our own solar system. The European Space Agency (ESA) ExoMars delivery platform is currently en route to Mars to search for biosignatures of Martian life, past or present. The lander element of the mission should reach the surface of Mars in 2018.
-------------------------------------
en.wikipedia.org/wiki/Drake_equation
en.wikipedia.org/wiki/Light_cone
Also check out the 'Wow!' signal:
www.flickr.com/photos/119411696@N08/12919655613/in/photol...
The Way the Sunshine Falls
Earth Day 2016
Other Technologically Advanced Worlds
'There is a point of view among astronomical researchers that is generally referred to as the Principle of Mediocrity. ...If the Sun and its retinue of worlds is only one system among many, then many other systems will be like ours: home to life. Indeed, to the extent that this is true, we should be prepared for the possibility that, even in the Milky Way galaxy, billions of planets may be carpeted by the dirty, nasty business known as life.'
Seth Shostak
-------------------
Like a lot of people I find it's always fun to speculate about the possibilities of technologically advanced alien civilizations existing in the Universe. In 1961 astronomer Frank Drake created an equation to estimate the number of such civilisations existing in our own galaxy with which communication might be possible (i.e. which are on our current / past light cone).
Each variable in the equation is a vital factor in the development of such civilisations. The Drake Equation has been refined over the decades to include, for example, the ability of a technological civilisation to survive an alien attack.
en.wikipedia.org/wiki/Drake_equation
There are two main arguments concerning the possibilities of complex biological life such as multicellular organisms (subsequently human intelligence on Earth) existing in the Universe at large. Those same arguments are concerned with the potential existence of technological civilisations capable of interstellar communication.
One side argues that the Universe is teeming with advanced technological civilisations (Frank Drake and Carl Sagan for example), the other that such civilisations are an improbable phenomenon. The Rare Earth hypothesis proposed by Peter Ward argues the latter.
We do know that one of the crucial factors in the development of multicellular biological life on Earth was the availability of stable sunshine for the two billion year period it took for slime and single-cell bacteria to evolve into multi-cellular life (one cell swallowed another and the two began working together). However, before this could happen a vast number of improbable variables and events had to exist and occur which, on the face of it, might or might not lend weight to the Rare Earth hypothesis that our planet and its complex lifeforms are the result of a one-in-a-galaxy run of good luck.
Such as:
The right location in the right kind of galaxy.
Orbiting at the right distance from the right type of star.
The right arrangement of planets (It has been argued that Jupiter with its enormous gravitational pull has, over billions of years, reeled in vast quantities of asteroids and other objects that might otherwise have collided with Earth).
A continuously stable orbit.
A terrestrial planet of the right size with plate tectonics.
A large moon (The giant impact theory hypothesizes that the Moon resulted from the impact of a Mars-sized body, Theia, with the very young Earth (approximately 4.5 billion years ago, in the Hadean eon - about 20 to 100 million years after the solar system coalesced). This giant impact, while providing a large moon and important local gravitational pull, gave the Earth its axial tilt and velocity of rotation, vital in creating stable seasons, predictable days and predictable tides.)
One or more evolutionary triggers for complex life.
The right time in evolution (avoiding mass extinction events: extreme climatic variations, super volcanoes or large meteorite/asteroid impacts).
(I'm adding that the random destruction of all non-avian dinosaurs 66 million years ago on Earth by an asteroid - the Chicxulub impact at the Cretaceous–Paleogene boundary on the Yucatán peninsula in Mexico - opened up the planet to mammals, smart creatures who got ever smarter very fast leading to Homo sapiens and our technological civilisation. What if that asteroid had not hit Earth? Perhaps the emergence of a technologically advanced dinosaur civilisation?)
Many argue that only some, or none, of the above conditions are necessary for the evolution of complex biological life and that we are restricting our estimates of the existence of complex life and subsequent technological alien civilizations in the Universe by our sheer lack of imagination.
We might also bear in mind the words of Seth Shostak when speculating about the possibilities of technological alien civilizations existing in the Universe:
'Humans have existed only for the last 0.001 percent of cosmic time. All of which says that - unless the Homo sapiens brain is the one-and-only instance of cogitating machinery - nearly all the intelligence that's out there is beyond our level. And that intelligence is more than just a little bit beyond.'
And finally, the Fermi paradox or "Where is everybody?"
Reasons:
Few intelligent civilizations ever arise.
Intelligent civilizations exist, but we see no evidence (civilizations are too far apart, it is too expensive to spread throughout the galaxy, civilizations broadcast signals for only a brief period of time, it is dangerous to communicate, and many others...).
The lifetime of intelligent civilizations is short (it is the nature of intelligent life to destroy itself, it is the nature of intelligent life to destroy others, they tend to experience a technological singularity, and others...).
It goes without saying that, aside from Earth, we have yet to prove the existence of life, past or present, in our own solar system. The European Space Agency (ESA) ExoMars delivery platform is currently en route to Mars to search for biosignatures of Martian life, past or present. The lander element of the mission should reach the surface of Mars in 2018.
-------------------------------------
en.wikipedia.org/wiki/Drake_equation
en.wikipedia.org/wiki/Light_cone
Also check out the 'Wow!' signal:
www.flickr.com/photos/119411696@N08/12919655613/in/photol...