Stupid Questions Open Thread Round 2

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Stupid Questions Open Thread Round 2 — LessWrong

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komponisto14y110

A couple of embarrassingly basic physics questions, inspired by recent discussions here:

On occasion people will speak of some object "exiting one's future light cone". How is it possible to escape a light cone without traveling in a spacelike direction?
Does any interpretation of quantum mechanics offer a satisfactory derivation of the Born rule? If so, why are interpretations that don't still considered candIdates? If not, why do people speak as if the lack of such a derivation were a point against MWI?

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MinibearRex14y10

If not, why do people speak as if the lack of such a derivation were a point against MWI?

The primary argument in favor of MWI is that it doesn't require you to postulate additional natural laws other than the basic ones we know for quantum evolution. This argument can pretty easily be criticized on the grounds that yes, MWI does require you to know an additional fact about the universe (the Born rule) before you can actually generate correct predictions.

0BlazeOrangeDeer14y

Nobody has derived the Born rule, though I think some have managed to argue that it is the only rule that makes sense? (I'm not sure how successful they were). I think people may count it against mwi because of either simple double standards or because it's more obvious as an assumption since it's the only one MWI needs to make. (In other theories the rule may be hidden in with the other stuff like collapse, so it doesn't seem like a single assumption but a natural part of the theory. Since MWI is so lean, the assumed rule may be more noticeable, especially to people who are seeing it from the other side of the fence.)

1wedrifid14y

Usually people do include traveling in a spacelike direction as a component of the 'exiting'. But the alternative is for the objects ('you' and 'the other thing') to be at rest relative to each other but a long distance apart - while living in a universe that does stuff like this. ie. Imagine ants on the outside of a balloon that is getting blown up at an accelerating rate.

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