Its also possible that life is very common in the universe, yet we are simply unable to detect it. This is known as the Fermi Paradox....
http://en.wikipedia.org/wiki/SETI
Quote:
|
The size and age of the universe incline us to believe that many technologically advanced civilizations must exist. However, this belief seems logically inconsistent with our lack of observational evidence to support it. Either the initial assumption is incorrect and technologically advanced intelligent life is much rarer than we believe, our current observations are incomplete and we simply have not detected them yet, or our search methodologies are flawed and we are not searching for the correct indicators.
|
The more data thats gathered the more we will eventually know. It may seem that life here on earth is a stroke of luck, that all the right conditions just happened to fall in place, and that this is exceedingly rare. The rare earth hypothesis does have some hard facts to back it up.....
http://en.wikipedia.org/wiki/Principle_of_mediocrity
Quote:
Earth is the right orbital distance from a non-binary, metal-rich star (the Sun) with stable radiation over an ideal frequency spectrum. If the Sun were larger, it would burn too quickly for life to evolve and if it were smaller, the Earth would need to be closer, making it tidally locked.
Earth has a nearly circular orbit. This condition is not rare in our solar system, possibly due to Jupiter's gravitational influence, but observations of exosolar planets suggest that it is rare in general.
Earth is a silicate rock with the prerequisite mass, plate tectonics, and iron core to protect developing life from radiation.
Jupiter and the other large outer planets shield the Earth from asteroids without destabilizing its orbit as well as shuttling water-rich comets from the outer solar system to the inner.
Earth has the perfect amount of water for a long-term active hydrosphere.
The Moon is anomalously massive, creating large oceanic tides, and stabilizing the Earth's axial tilt. According to Jacques Laskar's calculations this critical feature is otherwise impossible to achieve.
The manner in which the Moon was created, by collision of a mars-sized body with Earth, may have stripped the Earth of some of its crust material. This deficit of crust material allows plate tectonics. Without plate tectonics the Earth might undergo essentially complete volcanic resurfacing as Venus does.
The Earth's location within the galaxy is rare and important: "Not in the center of the galaxy, not in a globular cluster, not near an active gamma ray source, not in a multiple-star system, or near a pulsar, or near stars too small, too large, or soon to go supernova."
Earth's orbital and temperature stability over billions of years is exceedingly rare, as is its insulation from cataclysmic events.
|
This is in direct contradiction with SETI's guiding principle of mediocrity, which basically states that there is nothing special about humans or the earth.
I prefer to remain open minded and keep a 'wait and see' attitude. I certainly hope we're not all alone.
