thanks, ft - it is from a series of interviews between Phillip Adams (atheist and skeptic) and Paul Davies (physicist) on the abc website . Paul Davies is such a good communicator, he is one of the rare scientists who can explain science for ordinary people. that link I provided has links at the bottom of the page to more interviews with him, and they're all fascinating.

Look at these comments from another one of the interviews, are we alone?

Phillip: ...we're dealing with such immense numbers of suns and, presumably, of planets, that life forms may be as bountiful in the cosmos as they are on Earth. After all, in the observable universe there are 1020 — 100 billion billion — suns.

Paul: That's a lot, isn't it, a big number. Unfortunately not so big that if life formed as a result of an accidental shuffling of molecules — that is, if life is a chemical fluke — then it would be bound to occur twice.

Phillip: But what if you add to those 100 billion billion suns the number of possible planets? You are then dealing with an even greater number.

Paul: It's just another factor of ten or so. People are very bad at large number estimates. They think that a million is awfully big, and a billion just a bit bigger, and so on. Although 100 billion billion sounds like an enormous number, it is still absolutely tiny compared to the odds against forming life by random shuffling. It is undeniably true that the universe is vast: there are a huge number of stars and probably planets too. Nevertheless the odds against shuffling, say, amino acids into proteins, which we were talking about previously, are enormous — like one followed by 130 zeros as opposed to your puny number here of one followed by twenty zeros! A hundred billion billion doesn't begin to scratch the surface of the improbability of forming life, if it formed purely by accident. So if life is merely a chemical fluke, we are alone. The only possibility of us not being alone is if there is something other than just a random shuffling process involved.

Phillip: There are conflicting human emotions at work here. On the one hand, it is a very bleak thought, to suppose that we are alone in the universe. Many of us would like the company of user-friendly species from other galaxies. On the other hand, we have always been very arrogant; we rather like to think that we are at the centre of things.

Paul: In some cultures, yes. But not all. The same argument was raging even in ancient Greece over 2000 years ago. The Greek atomists believed that we are not unique. They reasoned that the universe is nothing but indestructible particles moving in the void. This led them to conclude that extraterrestrial beings exist because if atoms can come together in certain combinations to form living things here on Earth, then they might do so on other worlds, too.

.. the interview goes on to discuss the possibility of life on Mars, wormholes, and other strange things..