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Posts Tagged ‘Paul Davies’

I’m halfway through Paul Davies’s book The Eerie Silence, about the Search for Extraterrestrial Intelligence (SETI) project and the wider scientific and philosophical issues involved. One of the ways of investigating the probability of extraterrestrial life is to look at the vexed question of the probability of life on earth, and chapter 2 of the book is entitled, “Life: Freak side-show or cosmic imperative?”

Was there a high probability that any life, let alone intelligent life, would develop on earth? The answer is: we haven’t a clue. And that’s because we still have almost no understanding about how life developed on this planet in the first place; and we don’t even know if it started here anyway – it may have started on Mars and migrated on materials that got dispersed into the solar system and then fell to earth.

We simply don’t know how life began. As Charles Darwin said:

We might as well speculate about the origin of matter.

This lack of knowledge isn’t reflected in the ‘cosmic imperative’ mood of the scientific and journalistic moment. Many thinking people, in other words, believe that given the vastness of the universe the emergence of life must be almost inevitable. Alan Boss of the Carnegie Institution in Washington declared in 2009:

If you have a habitable world and let it evolve for a few billion years then inevitably some sort of life will form on it… It would be impossible to stop life growing on these habitable planets… There could be one hundred billion trillion Earth-like planets in space, making it inevitable that extraterrestrial life exists’ [25-26].

The flaw in this probability argument is obvious even to a non-scientist like myself. Boss uses the word ‘evolve’: if you let a habitable world ‘evolve’ then life is bound to emerge. That would be true if we had any evidence that a ‘world’ evolves. But we don’t. Life evolves, once it is started – we know that. But we can’t use an assumption about the progress of evolution within life as an argument that life itself, at its beginnings, is the result of a pre-life evolutionary process. We have no idea what such a process might involve, or any evidence that it took place, or any indication of what the probability of it taking place might be.

George Whitesides, Professor of Chemistry at Harvard University, gives the alternative view, which Paul Davies himself accepts. First of all he seems sceptical:

How remarkable is life? The answer is: very. Those of us who deal in networks of chemical reactions know of nothing like it… How could a chemical sludge become a rose, even with billions of years to try? … We (or at least I) do not understand. It is not impossible, but it seems very, very improbable [31].

But it’s not so much scepticism as a humble awareness of the impossibility of speaking about a high probability of life emerging when we know so little about what would or would not make it probable in the first place.

How likely is it that a newly formed planet, with surface conditions that support liquid water, will give rise to life? We have, at this time, no clue, and no convincing way of estimating. From what we know, the answer falls somewhere between ‘impossibly unlikely’ and ‘absolutely inevitable’. We cannot calculate the odds of the spontaneous emergence of cellular life on a plausible prebiotic earth in any satisfying and convincing way’ [31].

All we know is that it has happened at least once.

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VLA radio telescopes by stephenhanafin.

I’m dying to read Paul Davies’s new book The Eerie Silence: Are We Alone in the Universe? I know it’s a bit cheeky just pasting the the blurb from Amazon here for a book I haven’t read, but it does summarise the fascination of the whole SETI project:

On April 8, 1960, a young American astronomer, Frank Drake, turned a radio telescope toward the star Tau Ceti and listened for several hours to see if he could detect any artificial radio signals. With this modest start began a worldwide project of potentially momentous significance. Known as SETI — Search for Extraterrestrial Intelligence — it is an amalgam of science, technology, adventure, curiosity and a bold vision of humanity’s destiny. Drake has said that SETI is really a search for ourselves — who we are and what our place might be in the grand cosmic scheme of things. Yet with one tantalizing exception, SETI has produced only negative results. After millions of hours spent eavesdropping on the cosmos astronomers have detected only the eerie sound of silence. What does that mean? Are we in fact alone in the vastness of the universe? Is ET out there, but not sending any messages our way? Might we be surrounded by messages we simply don’t recognize? Is SETI a waste of time and money, or should we press ahead with new and more sensitive antennas? Or look somewhere else? And if a signal were to be received, what then? How would we — or even should we — respond?

Bryan Appleyard had an article in the Times recently about Jill Tarter, who is the scientist on whom Jodie Foster’s character in Contact was based. He writes about Drake’s work:

He came up with the Drake Equation, a way of calculating the number of intelligent civilisations in the Milky Way, our galaxy. To solve the equation most of the terms have to be guessed. But making, he says, reasonable assumptions, Drake reckons there are 10,000 alien civilisations in our galaxy.

“I’m not being super-pessimistic or super-optimistic when I say that.”

Unfortunately, 50 years on and in spite of the odd wow moment, Seti has found none of them.

In the institute the equation is everywhere — on T-shirts, posters and even on a plaque at reception. It ties together everything they do, which means not just scanning the skies but investigating Mars and meteors, planets and protozoa.

Only a small proportion of this place is actually devoted to Seti proper, the rest is a specialist science operation. But everything feeds into the equation. And all the other projects bring in money in the form of research grants, primarily from the nearby Nasa Ames Research Center.

The equation seems to say life is out there, probably in abundance, that the Milky Way is more like a cocktail party than a desert. So where the hell are they all?

The scientist Enrico Fermi once said that if we hadn’t heard from the aliens, they weren’t there. The universe is so old — 13.7 billion years — that a single intelligence would have had time to colonise the galaxy. At the institute they step round this. Nobody here doubts there is life out there. “I bet everybody a couple of Starbucks that we’ll find ET within a couple of dozen years,” says the gleeful and buoyant Seth Shostak, senior astronomer at the institute.

“I cannot imagine a scenario in which life on Earth is unique,” says Mark Showalter, expert on planetary rings and discoverer of three new moons and three new rings, principal investigator.

All say the real miracle would not be ET but the complete absence of intelligent life. “If there are aliens out there,” says Shostak, “that’s miraculous; if there aren’t, that’s a miracle.”

No aliens would mean that in our entire galaxy — 100,000 light years across (for perspective, the moon is 1.3 light seconds from Earth), 1,000 light years thick, 100 billion stars, countless planets — and in the entire universe, 170 billion galaxies, 14 billion years old, humans were a one-off. Would that make us feel special or lonely? It should certainly make us feel weird.

For me, the alien questions go hand-in-hand with the early hominid questions – hence my fascination with them both. Is there something unique about human intelligence, imagination, creativity and freedom? Were we ‘alone/unique’ even in the time of the Neandertals (and the two other possible contemporaneous hominids: more posts to follow)? Are we alone now?

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