'It has been estimated that there are between 1 billion and 30 billion planets in our galaxy, and about 100 billion galaxies in the universe. Knocking a few noughts off for reasons of ordinary prudence, a billion billion is a conservative estimate of the number of available planets in the universe. Now, suppose the origin of life, the spontaneous arising of something equivalent to DNA, really was a staggeringly improbable event. Suppose it was so improbable as to occur on only one in a billion planets. [...] Even with such absurdly looking odds, life will still have arisen on a billion planets - of which Earth, of course, is one.'
'I disbelieve all the flying saucer stories that have little green men, not because they are little and green, but because they are men. Little green splots would be so much more believable.'
'Thus, when we go out into space there may be more to meet us than we expect. I would look forward not only to our extra-terrestrial brothers who share life-as-we-know-it. I would hope also for an occasional cousin among the life-not-as-we-know-it possibilities. In fact, I think we ought to prefer our cousins. Competition may be keen, even overkeen, with our brothers, for we may well grasp at one another's planets; but there need only be friendship with our hot-world and cold-world cousins, for we dovetail neatly. Each stellar system might pleasantly support all the varities, each on its own planet, and each planet useless to and undesired by any other variety. How easy it would be to observe the Tenth Commandment then!'
'In the search for life elsewhere in the solar system, we tend to plan for life as we know it, even down to the nucleic acid bases or base sequences used in organisms elsewhere. What if they don't use DNA? Or RNA? Or linear information-bearing polymers? Do they have to use liquid water as the universal biosolvent? The universe has surprised us before with its variety, in spite of the simplicity and small number of fundamental physical laws'.
'Were going through a tremendous biological boon in learning so much about life on this planet. A lot of this advancement is due to remarkable techniques that have been developed that are extremely sensitive, but also highly specific. But that very sensitivity, because of its specificity, makes it almost useless in the quest to look for life elsewhere. That is, unless life elsewhere is made of exactly the same building blocks that we're made out of and using similar sequences. So what we need to do is come up with more general ways to look for life, but increase the sensitivity in order to find that life. If we come up with techniques, knowing the organisms that we're looking for, we might find some organisms here on Earth previously not known, much less finding things on other planetary bodies'.
'Nowhere in space will we rest our eyes upon the familiar shapes of trees and plants, or any of the animals that share our world. Whatsoever life we meet will be as strange and alien as the nightmare creatures of the ocean abyss, or of the insect empire whose horrors are normally hidden from us by their microscopic scale.'
'Aliens will not resemble anything we've seen. Considering that octopi, sea cucumbers, and oak trees are all very closely related to us, an alien visitor would look less like us than does a squid. Some fossils in the ancient Burgess shale are so alien that we can't determine which end of the creature is up, and yet these monsters evolved right here on Earth from the same origins as we did.'