P. C. W. Davies

Physicist/cosmologist/astrobiologist Paul Davies takes a thought-provoking look at various questions surrounding the idea of life elsewhere in the universe and our attempts to find it. What are the odds that life, and intelligent life, exist elsewhere? How can we even go about making educated guesses on that? What kind of evidence might change our estimation of the odds? If such life does exist, what might it be like? And what, if anything, does it mean that in fifty years of looking, we show more haven't found any intelligent signals, or at least none we could be remotely sure about? Is the conventional, radio-based attempt to detect alien communications really the best way to go about it? What other kinds of evidence might aliens leave of their existence, and how might we look for those? And what happens if we do find something? (Davies is particularly well-placed to address that last question, as he is the chairman of the group that makes protocol recommendations for the possible event.)

Some of Davies' speculations are out there enough that they almost border on the wacky, but even those exist to make a reasonable point: that our traditional methods of looking tend to assume that aliens are too much like us, when, technologically speaking, what we're like is already changing on a scale of decades.

Overall, it's a provocative, engaging, interesting read, albeit very far from the last word on the subject. show less

That our oldest known ancestors were organisms living in water is one thing; that life itself originated in water is quite another. It was the hypothesis emitted by Darwin himself, picked up by many since then, and yet... And yet, two relatively recent and major discoveries have completely blown away our preconceived ideas on the topic.

First, the existence of so-called extremophiles that is, organisms living within the depth of the Earth and at extreme temperatures. Since such organisms seem show more to have been protected, within such enclosed environment, from all sorts of cataclysmic events that had constantly impacted our planet about 4 billion years ago (comets, meteorites...) they defy the idea that life appeared in water to make the centre of the Earth a matrix as plausible. Studying them, then, could lead to more tangible results that what our hypothetical experiments in laboratories have been yielding so far (e.g. the Miller-Urey one, that the author retells here in critical passages....).

Then, the fact that some of these cosmic objects which came to crash themselves upon the surface of the Erath (e.g. the Murchison meteorite) contain elements necessary to life, including amino acids. Of course, the presence of such elements is far from proving the presence of life itself! But, nevertheless, it raises important questions -has life first appeared on Earth? Has it first appeared elsewhere in the universe, and journeyed to the Earth through a cosmic collusion? Or is it the product of a symbiosis between earthly elements and extra-terrestrials ones? Even more challenging: what are the probabilities for life, even under its most primitive forms, to exist elsewhere, on other planets? Paul Davies, here, delves particularly upon the case of Mars, since its conditions about 4 billions years ago seemed to have been more favourable to life than that of the Earth, with which, also, contacts were more frequents through more frequent cosmical impacts. These are fascinating questions indeed: are we an isolated accident, or, the logical product of a vast ecosystem (the Universe itself) whose conditions are favourable to life?

Engrossing from beginning to end, accessible, rich in details, the author knows how to showcase his arguments without falling into sensationalism or wild speculations, which is quite a feat given the nature of his hypothesis! His questioning, then, put forth with such precautions, make of this book a must read for anyone interested in such an enigma as the possible origins of life itself. Superb! show less

This a top-class survey of the subject—including some of its profounder aspects because this isn’t just a scientific problem, it’s a philosophical and even religious one too.
    Scientifically, it hinges on the role which chance may, or may not, have played. Is life an inevitable expression of the various laws of nature: “run” the universe a thousand times over and would you always get life (and perhaps mind)? Or is it a flukey outcome of those laws, a falling of the cosmic dice show more so improbable it would likely never be repeated? The first possibility not only sounds like foresight, a Plan, but since the laws of nature work the same way everywhere then life will prove to be common throughout the universe. The second, by contrast, leaves us alone and, perhaps, meaningless as well.
    To explore such ideas, though, you need the relevant background information, and Davies guides us through it in exceptionally plain language. For a start, there’s the whole business of what “life” actually is, and what it is not. Creationists, for instance, often argue that its mere existence contradicts the laws of physics—entropy and all that, the thermodynamic running down of the universe—and Chapter 2 includes a wonderfully clear explanation of how that is a misunderstanding both of living things and the universe itself. Then there’s DNA and the mind-numbing complexity of cell and genetic code alike. And there’s the whole subject of where life may have begun (if indeed it ever did): on the Earth’s surface, or perhaps miles beneath it inside rocks then spreading up to the surface? This latter, the world of subterranean “extremophile” microbes, is a fascinating and relatively new subject which questions the assumption “…that surface life is ‘normal’, and subterranean life is an off-beat adaptation… Could it be that the reasoning is literally upside down, and that the truth is just the opposite?” Then again though, did life begin on Earth at all, or did it arrive here from elsewhere (from Mars for instance, which early in its own history was very Earthlike)? Or did life never have a beginning and has always existed? This last one is just part of the whole question of whether the universe itself had a beginning or not, or is infinitely old.
    There’s a lot more here besides and, although it was last updated in 2003, this book is still not only a clear-headed guide through its subject, but an unusually deep one too. Absolutely excellent. show less

In 2010, the SETI - Search for Extra-Terrestrial Intelligence - initiative celebrated its 50th anniversary. And so physicist/cosmologist/astrobiologist Paul Davies was asked to write something. Rather than just write a simple back-patting congratulation, he decided to try and write about the whole concept: Why are we looking for signs of alien intelligence, how are we looking for it, how likely is it to exist, how likely are we to find it (or they to find us), what would we be likely to show more find, how would we react...? Is it possible that the big fat Zero that's been the result of our search so far means that we really are all alone in the universe, or are we just looking for a very tiny needle in a very large haystack? To do this, obviously, he can't just write about radio telescopes, he needs to go back and revisit the fundamentals: how does life arise and evolve, how would you travel or communicate across large distances, how would we even recognise technology that's thousands or millions of years beyond our own?

The Eerie Silence is a great little primer on most of these subjects, though at 210 pages you'll probably find yourself wanting to dig deeper in some areas. Some of the stuff that fascinated me:

Our telescopes keep finding more and more planets outside the solar system - 846 identified ones as of today - and with all the stars out there, it stands to reason that there could be millions of habitable planets in our galaxy alone; ie planets made of rock, in the "goldilocks zone" (not too hot, not too cold), with liquid water and an atmosphere. Theoretically, there could be a lot of aliens out there. But habitable doesn't mean inhabited; the problem when trying to figure out how likely that is, is that we simply don't have any indication of how easy the step is from "theoretically habitable" to "practical rocket scientists". As far as we know for sure (though Davies presents some interesting speculations), life has arisen in the universe exactly once (around 3.5 billion years ago on Earth) and evolved intelligence exactly once (Homo, about 2 million years ago), and one single data point doesn't give us any indication of how likely the same thing is to happen on other planets; it could happen every time, or never. For all we know, the universe could be empty, or it could be teeming with life that never evolved "past" bacteria or dinosaurs (going with the common fallacy that some animals are "more evolved" than others), or the 6-7 billion years that the average planet has before its sun supernovas simply isn't enough time to perfect interstellar travel. If there are aliens out there to communicate with, why wouldn't they have already done so? It's a bit like Stephen Hawking's question: if time travel is possible, why have we never seen any tourists from the future?

What would we be looking for, and how would we recognise it when we see it? We take for granted that communication from other civilisations would come as, say, a radio signal carrying prime numbers, because that's what we can hope to read. If there are others out there, they may well be trying to communicate in ways we haven't even conceived of yet.

For that matter, what would other, more advanced civilisations even want with us? Science fiction is full of aliens looking to humans as cheap sources of food, labour or concubines, which is just silly - if you're able to communicate across light years, you can't have much need for manual labour. How do we know they haven't noticed us and decided not to bother with us until we show some sign of intelligence? After all, we've only been broadcasting weak radio signals for about 100 years (and have pretty much stopped by now, since we're mostly using fiberoptics and satellites these days), and anyone looking at us from more than 110 lightyears away wouldn't even know that we've mastered flight.

What would members of an ancient civilisation even be? Even assuming they started out roughly like us, we're already edging into cyborg territory ourselves; would a species that's had another 40,000 years of "civilisation" even be biological anymore? (Yes, Davies is an Olaf Stapledon fan.) Would we even recognise them as life? Would we recognise their technology as artifice?

For all the high-flying speculations, The Eerie Silence is a sober and realitic look at the possibility of finding and communicating with hypothetical extraterrestrial civilisations. In the end, Davies is very sceptical that they even exist, but that's not his worst nightmare, nor a reason to stop looking. The worst-case scenario, he claims, is this: we keep looking, and we discover that there's plenty of life in the universe, and that it's occasionally evolved into intelligent beings... and that none of them have survived long enough to communicate with others before they wiped themselves out. If that's the case, then that's definitely something we need to know.

Or, as xkcd put it:

The universe is probably littered with the one-planet graves of cultures which made the sensible economic decision that there's no good reason to go into space--each discovered, studied, and remembered by the ones who made the irrational decision. show less