MOST IMPORTANT PLACE IN THE UNIVERSE:

Our Cosmic Self-Esteem: Astronomer Royal, Sir Martin Rees describes how for the first time, humans as a species may start to change in observable ways within single lifetimes and under some loose control of our own influence. If this future plays out, the future itself becomes more difficult to forecast. ( Helen Matsos, Jan 10, 2005, AstroBiology)

HM: In your book "Our Cosmic Habitat," you say that a quadrant of the sky seems well suited to human habitability. With the discovery of extrasolar planets, it is now thought that as many as a quarter of the stars in our galaxy have solar systems around them. How do these findings relate to the ideas in your book?

MR: The realization that planetary systems are common around many stars is an exciting development. We don't know what fraction of those stars would have habitable planets, but most of us confidently expect there should be many planets in our galaxy that resemble the young Earth, on which life might have gotten started.

It would be exciting to find any evidence for biological activity on those planets. Within ten to twenty years we could find this. Obviously the detection of any life beyond the Earth would be of great importance. It would show us that the probability of life getting started was not infinitesimally small, that it happened not just once but more than once and probably very many times.

The search for intelligent life is a different problem, and that may fail even if the search for simple life succeeds. Many people would be depressed if the search for intelligent life failed. It would be disappointing if the SETI searches yielded no results. It would make the cosmos seem a lonelier place.

But, I think there'll be some compensations, which I discuss in my book. In particular, I think it would raise our cosmic self-esteem. We could then regard our Earth, tiny though it is, as perhaps being the most important place in the galaxy. It might be the only place where life has evolved into a complex biosphere, containing creatures with structures like our brains, able to contemplate their origin.

I think another perspective astronomy brings to bear on these issues is that astronomers are aware of the tremendous time span lying ahead of us. Most educated people are aware that we are the outcome of nearly four billion years of Darwinian selection, and I think many tend to think humans are the culmination of all that. But astronomers know that our sun is less than halfway through its life span. Our sun will flare up and die six billion years from now, a period of time longer than the sun's history so far. Some people imagine that there will be humans watching the sun's demise six billion years from now, but any creatures that exist then will be as different from us now as we are from bacteria or amoebae.

We should think of ourselves as still in the early stage of the emergence of complexity and intelligence. It's hard to conceive what forms that might take on Earth or far beyond Earth. But I think we should see ourselves as nowhere near the culmination of evolution.

Even if life is now very rare in the galaxy or unique to Earth, that doesn't mean life is forever going to be a trivial afterthought in the cosmos. In the time lying ahead, life from Earth could spread all through the galaxy. The Earth could be cosmically important as the seed from which life spreads more widely.

HM: So we may evolve to a high enough state that we could disperse as an intelligent species throughout the universe. But what about the possibility that life already exists elsewhere?

MR: It's possible that the universe is already teaming with life, but it's equally possible that life is very rare and almost unique to the Earth. In the later case, some people may think that makes life an irrelevant triviality in the cosmos. But if we are mindful of the time that lies ahead, in that far future, life starting from Earth has abundant time to spread through the entire galaxy.

Geocentrism and Evolution as Intelligent Design--can't beat it.

Posted by Orrin Judd at January 12, 2005 9:12 AM