From Derek Bolton, Sydney, Australia
Ernest Ager remarks that a “one in a billion” chance of life arising isn’t as much of a hurdle as Bryn Glover considers it to be, given the vast numbers of star systems in the universe. Since the article that this one-in-a-billion figure comes from provided no scope of space or time, it is meaningless. A one-in-a -billion chance that it will happen in the local swimming pool next Thursday, or that it has happened anywhere else in the age of the universe?
However, the notion that our universe is just one in a multiverse of all possible universes offers a different approach. We may guess that the vast majority of universes produce nothing of much complexity; that an overwhelming proportion of those that do are quite inimical to life; that in all but a tiny fraction of those where life could arise, it remains so unlikely that it only happens once; and so forth. On that basis, the odds are that we find ourselves in a universe of the third kind (Letters, 24 January).
