Re: Observation selection effects

From: Hal Finney <hal.domain.name.hidden>
Date: Thu, 7 Oct 2004 18:33:10 -0700 (PDT)

Stathis Papaioannou writes:
> Suppose that according to X-Theory, in the next minute the world will split
> into one million different versions, of which one version will be the same
> sort of orderly world we are used to, while the rest will be worlds in which
> it will be immediately obvious to us that very strange things are happening,
> eg. dragons materialising out of thin air, furniture levitating, the planet
> Jupiter hurling itself into the sun, etc. I think it is reasonable to expect
> that if X-Theory is correct, we will very likely see these bizarre and
> frightening things happen in the next minute.

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.

> Now, here we are, a minute later, and nothing bizarre has happened after
> all. Does this mean that X-Theory is probably wrong? Perhaps not. After all,
> the theory did predict with 100% certainty that one version of the world
> will continue as before. The objection to this will no doubt be, "yes, but
> how likely is it that WE end up in that particular version?" And the answer
> to this objection is, "it is 100% certain that WE end up in that particular
> version; just as it is 100% certain that 999,999 copies of us end up in the
> bizarre versions". Those 999,999 copies are not continuing to type away as I
> am, because they are running around in a panic.

Would you agree that those who assume that such an outcome (no bizarre
events) disproves X-theory will be right more often than they are wrong?
Hence adopting such a policy will generally be successful, and beings
who base their decisions on such a rule will become more numerous and
influential in the multiverse.

Even though there are universes where this rule (that is, the rule "a
theory which predicts something we don't see is probably an incorrect
theory") does not work, still it is a good rule to follow.

Hal Finney
Received on Thu Oct 07 2004 - 22:18:56 PDT