On Wed, 25 May 2005, Stathis Papaioannou wrote:
Consider these two parallel arguments using a version of the anthropic
(a) In the multiverse, those worlds which have physical laws and
constants very different to what we are used to may greatly predominate.
However, it is no surprise that we live in the world we do. For in those
other worlds, conditions are such that stars and planets could never
form, and so observers who are even remotely like us would never have
evolved. The mere fact that we are having this discussion therefore
necessitates that we live in a world where the physical laws and
constants are very close to their present values, however unlikely such
a world may at first seem. This is the anthropic principle at work.
(b) In the multiverse, those worlds in which it is a frequent occurence
that the laws of physics are temporarily suspended so that, for example,
talking white rabbits materialise out of thin air, may greatly
predominate. However, it is no surprise that we live in the orderly
world that we do. For in those other worlds, although observers very
much like us may evolve, they will certainly not spend their time
puzzling over the curious absence of white rabbit type phenomena. The
mere fact that we are having this discussion therefore necessitates that
we live in a world where physical laws are never violated, however
unlikely such a world may at first seem. This is the *extreme* anthropic
principle at work.
If there is something wrong with (b), why isn't there also something
wrong with (a)?
Good point, this is a fundamental weakness of the AP. If you take it to
extremes, we should not be surprised by *anything* because the entire
history of our past light-cone to date, down to specific microscopic
quantum events, is required in order to account for the fact that you and
I are having this particular exchange. To give the AP force, you have to
work on the most general possible level (hence it was a big mistake for
Barrow & Tipler to restrict it to "carbon-based life forms" in their book,
certainly not in line with Brandon Carter's original thought).