[MHGinTN]

You have made a common error, in taking the 4.5 billion years our planet has been existing and dividing it into the approx. 15 billion years since the Big Bang, and found we are in the last one third so why not life evolving during the previous approx. eleven billion?... The quiet state of our neck of this spiral galaxy is as important to the possibility of life catching hold and evolving as the big bnag as step one. The violent nature of galaxies and stars interacting is the usual state of the universe of galaxies. Our position and the state of our spiral galaxy is dependent upon the rest of the galaxy and the other galaxies! A delicate balance has only been possible in our galaxy for a window in which life on earth has been possible and a period long enough for the life to rise to the level of complexity we see.

Rememeber, the first stars did not have planets with heavy elements circling them. All the heavier elements than helium and lithium were generated by the life cycle and death of stars. Followed by the dispersion of these elements to be gathered into clouds then galaxies that eventually generated stars and planets as we have now. In short, we may be at the leading edge of the process which can allow for the formation of conditions absolutely necessary for the rise of life and continued development thereof. How long does it take to destroy the first stars, collect the dust in clouds then generate galaxies? How long must the process run to reach a quiet enough state such as our planet has arisen in?

If you would like to read and listen to more along this line of reasoning, try linking to reasons.org an astrophysicists explains the notion much better than simple ol' me.

[Sicon]

I'm really not so concerned about when life may or may not have been able to develop during the 15 billion or so years of the universe's existence, so I'm not making any "common error". Besides, you're talking about things in strictly theoretical terms, so how could I be in error even if I did assume that life could have developed elsewhere 10 billion years or more ago? No one knows one way or the other on that count. Besides, you're talking about conditions making development of life as WE know it possible. Who knows what else might have cropped up?

The assumption that life has been around elsewhere for 11 billion years, or 15 billion years, 4 billion years, or whatever, makes no difference to what I am saying. And that is that 1) the odds of our having been noticed, much less visited, by another civilization in the 70,000 or so years of human existence, or in the 107 years since we started generating signals that might be detected beyond the bounds of our own planet, are incredibly small, and 2) that there is still NO credible, concrete, scientifically verifiable and conclusive evidence proving the existence of aliens.

Sure, we could be the leading edge of the development of life in the universe, but that misses the point I am trying to make. Whether I allow for the possibility of life being able to develop any sooner than it has here or not doesn't change things in any significant way.