richard_dawkins_-_the_god_delusion

W H Y T H !• R E A I. M O S "I" C 1- R T A 1 N L Y i S NO C, O I) 145
obviously they all missed, or I wouldn't be here thinking about it.'
But he could still, forgivably, wonder why they all missed, and toy
with the hypothesis that they were bribed, or drunk.
This objection can be answered by the suggestion, which Martin
Rees himself supports, that there are many universes, co-existing
like bubbles of foam, in a 'multiverse' (or 'megaverse', as Leonard
Susskind prefers to call it).* The laws and constants of any one
universe, such as our observable universe, are by-laws. The multiverse
as a whole has a plethora of alternative sets of by-laws. The
anthropic principle kicks in to explain that we have to be in one of
those universes (presumably a minority) whose by-laws happened
to be propitious to our eventual evolution and hence contemplation
of the problem.
An intriguing version of the multiverse theory arises out of considerations
of the ultimate fate of our universe. Depending upon the
values of numbers such as Martin Rees's six constants, our universe
may be destined to expand indefinitely, or it may stabilize at an
equilibrium, or the expansion may reverse itself and go into contraction,
culminating in the so-called 'big crunch'. Some big crunch
models have the universe then bouncing back into expansion, and
so on indefinitely with, say, a 20-billion-year cycle time. The
standard model of our universe says that time itself began in the big
bang, along with space, some 13 billion years ago. The serial big
crunch model would amend that statement: our time and space did
indeed begin in our big bang, but this was just the latest in a long
series of big bangs, each one initiated by the big crunch that
terminated the previous universe in the series. Nobody understands
what goes on in singularities such as the big bang, so it is conceivable
that the laws and constants are reset to new values, each time.
If bang-expansion-contraction-crunch cycles have been going on
for ever like a cosmic accordion, we have a serial, rather than a
parallel, version of the multiverse. Once again, the anthropic
principle does its explanatory duty. Of all the universes in the series,
only a minority have their 'dials' tuned to biogenic conditions. And,
of course, the present universe has to be one of that minority,
because we are in it. As it turns out, this serial version of the
multiverse must now be judged less likely than it once was, because
* Susskind (2006) gives a splendid advocacy of the anthropic principle in the
megaverse. He says the idea is hated by most physicists. I can't understand why. I
think it is beautiful - perhaps because my consciousness has been raised by
Darwin.