Hal Finney writes:
>Not to detract from your main point, but I want to point out that
>sometimes there is ambiguity about how to count worlds, for example in
>the many worlds interpretation of QM. There are many examples of QM
>based world-counting which seem to show that in most worlds, probability
>theory should fail.
I'm not sure what examples you have in mind here, but this is actually the
general point I was trying to make: probability theory doesn't seem to work
the same way in a many worlds cosmology, due to complications such as
observers multiplying and then not being able to access the entire
probability space after the event of interest.
Consider these three examples:
(A) In a single world cosmology, I claim that using my magic powers, I have
bestowed on you, and you alone, the ability to pick the winning numbers in
this week's lottery. If you then buy a lottery ticket and win the first
prize, I think it would be reasonable to concede that there was probably
some substance to my claim (if not magic powers, then at least an effective
way of cheating).
(B) In a single world cosmology, I announce that using my magic powers, I
have bestowed on some lucky gambler the ability to pick the winning numbers
in this week's lottery. Now, someone does in fact win the first prize this
week, but that is not surprising, because there is almost always at least
one winner each week. I cannot reasonably claim to have helped the winner
unless I had somehow tagged him or otherwise uniquely identified him before
the lottery was drawn, as in (A).
(C) In a many worlds cosmology, I seek you out as in (A) and make the same
claim about bestowing on you the ability to pick the winning numbers in this
week's lottery. You buy a ticket, and win first prize. Should you thank me
for helping you win, as in (A)? In general, no; this situation is actually
more closely analogous to (B) than to (A). For it is certain that at least
one future version of you will win, just as it is very likely that at least
one person will win in the single world example. I can only claim that I
helped you win if I somehow identified which version in which world is going
to win before the lottery is drawn, and that is impossible.
Stathis Papaioannou
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Received on Fri Oct 08 2004 - 11:03:54 PDT