[SEQ RERUN] Living in Many Worlds

MinibearRex

Today's post, Living in Many Worlds was originally published on 05 June 2008. A summary (taken from the LW wiki):

The many worlds of quantum mechanics are not some strange, alien universe into which you have been thrust. They are where you have always lived. Egan's Law: "It all adds up to normality." Then why care about quantum physics at all? Because there's still the question of what adds up to normality, and the answer to this question turns out to be, "Quantum physics." If you're thinking of building any strange philosophies around many-worlds, you probably shouldn't - that's not what it's for.

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Today's post, Living in Many Worlds was originally published on 05 June 2008. A summary (taken from the LW wiki):

The many worlds of quantum mechanics are not some strange, alien universe into which you have been thrust. They are where you have always lived. Egan's Law: "It all adds up to normality." Then why care about quantum physics at all? Because there's still the question of what adds up to normality, and the answer to this question turns out to be, "Quantum physics." If you're thinking of building any strange philosophies around many-worlds, you probably shouldn't - that's not what it's for.

Your hypothetical has nothing to do with quantum mechanics or many worlds, and everything to do with special relativity. "Unobservable components of the wavefunction", in the many world sense, are areas where a different decisions was made or a different outcome observed.

In fact, extending it to many worlds actually hurts the point you want to make. The "(counterfactual) agent" makes both decisions (exploit, be kind), and you make both decisions. Further, you can't win in every world. Consider Newcomb's problem- even if omega (the predicting agent) is correct at 99.99%, there are worlds where two boxing is a losing proposition (omega got it wrong). In fact,the rule 'two-box on Newcomb problems' always creates two worlds- one where you are a winner and one where you are a loser.

So in many worlds, you can't assert such a policy would be a mistake- in some worlds it is, and in some it isn't.

Your hypothetical has nothing to do with quantum mechanics or many worlds, and everything to do with special relativity.

The hypothetical has nothing to do with quantum mechanics. It was obviously, and explicitly constructed to address the specific claim being replied to, using no set up more complex than physical movement. That claim being:

You should be able to justify any particular course of action without a metaphysical commitment to the reality of unobservable components of the universe's wave function.

It so happens that asr's reply indicate... (read more)

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Special relativity hangs out in a nice, flat, well behaved, Minkowski space where this sort of thing cannot happen. It takes general relativity and specifically a universe with accelerating expansion (such as ours probably is).

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