50 Years of Eerie Silence is Not a Long Time
If you ask the astronomers at the sharp end of SETI why they think there has been an eerie silence they’ll say, “Well we only have been doing it for 50 years.” “We’ve just started.” “What more do you expect?” “It’s a big universe out there.” And in fact, to put that into context - they look carefully. It’s just a few thousand stars. There are 400 billion stars within our Milky Way galaxy alone, so it is a needle in a haystack search.
Of course it’s easy to conclude simply that they just haven’t been doing it long enough or hard enough. It’s no surprise they haven’t heard anything, but the alternative is that we are indeed alone in the universe and it’s impossible to answer that question because there are so many unknown factors. If we’re looking for intelligence in the universe I think everybody assumes that this has to start with life and so the question is, how likely is it that there will be life elsewhere in the universe?
Now when I was a student almost nobody thought there was any life beyond Earth. Today it’s fashionable to say that there is life all over the place, that the universe is teeming with it, but the scientific facts on the ground haven’t really changed. We’re still just as ignorant as we were 40 or 50 years ago about how life began. We’ve got a very good theory of the evolution of life once it gets started, but how does it get going in the first place? We don’t need a blow by blow account of exactly how it started on Earth, but we would at least like to know whether it was a very probable event or very improbable event and in our present state of ignorance we can’t even pin that down. We can’t even bracket the odds.
It could have been a stupendously improbable fluke, a freak chemical accident that occurs just once in the universe or it could be that life emerges automatically and naturally as part of the underlying scheme of things. Maybe the universe has intrinsically bio friendly laws that bring life into being all over the place. We don’t know. It’s only fashion that is said the pendulum is swung from extreme skepticism about extraterrestrial life to extreme credulity. The truth is somewhere in between, but to pin it down we’ve really got to address that question of how likely is it that life will arise on an Earth-like planet.
I should say we know that there are many, many other Earths out there. We’re almost certain that there will be upwards of a billion Earth like planets in our galaxy alone, so there is no lack of real estate where life might happen, but what we don’t know is how likely it is given the real estate, given a wonderful pristine planet like Earth how likely is it that life will pop up inhabited? We don’t know the answer to that.
via Paul Davies
About Paul Davies:
Paul Davies is a theoretical physicist, cosmologist, astrobiologist, and bestselling author. He is Director of the Beyond Center for Fundamental Concepts in Science and co-Director of the Cosmology Initiative, both at Arizona State University. Previously he held academic appointments at the Universities of Cambridge, London and Newcastle upon Tyne in the UK, before moving to Australia in 1990, initially as Professor of Mathematical Physics at The University of Adelaide. Later he helped found the Australian Centre for Astrobiology in Sydney.
Davies’s research focuses on the “big questions” of existence, ranging from the origin of the universe to the origin of life, and include the nature of time, the search for life in the universe, and foundational questions in quantum mechanics. He helped create the theory of quantum fields in curved spacetime, with which he provided explanations for how black holes can radiate energy, and what caused the ripples in the cosmic afterglow of the Big Bang. In astrobiology, he was a forerunner of the theory that life on Earth may have come from Mars. He is currently championing the theory that Earth may host a shadow biosphere of alternative life forms.
Davies has lectured on scientific topics at institutions as diverse as The World Economic Forum, the United Nations, the Commission of the European Union, Google, Windsor Castle, The Vatican and Westminster Abbey, as well as mainstream academic establishments such as The Royal Society, The Smithsonian Institution, and the New York Academy of Sciences. Davies devised and presented a series of 45 minute BBC Radio 3 science documentaries and a one-hour television documentary about his work in astrobiology, entitled “The Cradle of Life.” Among his bestselling books are “The Mind of God,” “How to Build a Time Machine,” and “The Goldilocks Enigma.” His latest book, “The Eerie Silence,” was published by Houghton Mifflin Harcourt in 2010.