4 ms·

Some nit-picks: > Until a particle is observed, an act that causes the wave function to “collapse,” The "collapse" is a overly-simplistic way to interpret QM

Some nit-picks: > Until a particle is observed, an act that causes the wave function to “collapse,” The "collapse" is a overly-simplistic way to interpret QM experiments. It's not well-defined because no one's ever been able to define the "observer". > Quantum mechanics, in contrast, is inherently nonlocal. This is false, and a common misinterpretation of QM. We do not have any evidence of information travelling faster than the speed of light.

ewjordan 10y ago
That's not fair - plenty of people have defined "observer" in plenty of different ways (including defining it away, like decoherence supporters would prefer), it's just that there's no consensus because it's mostly a matter of philosophy without any experimental consequences. As for nonlocality, entanglement is a fundamentally nonlocal feature of quantum mechanics. There's no way to excise that from the theory, even if you can't exploit it to transmit information faster than light. I'd say calling it inherently nonlocal is entirely fair, that's a very different claim than that we can transmit information faster than light. ...which, as an aside, would not even in and of itself necessarily be problematic, closed timelike loops (for instance) are perfectly fine and good as long as you account for the fact that quantum interference will have very strong effects even at a macro scale in such geometries (the grandfather paradox gets interfered away, more or less, even if macroscopically unlikely things need to happen to end up with a reinforced consistent timeline).
VladKovac 10y ago
Quantum mechanics given a single world would have to be nonlocal based on bell's theorem. Only Many Worlds can give a local account which might work.
naasking 10y ago
> This is false, and a common misinterpretation of QM. We do not have any evidence of information travelling faster than the speed of light. It's actually not false as stated. The author didn't say information travels FTL. Copenhagen gives up realism to satisfy Bell's theorem, but is still non-local.

ewjordan 10y ago

That's not fair - plenty of people have defined "observer" in plenty of different ways (including defining it away, like decoherence supporters would prefer), it's just that there's no consensus because it's mostly a matter of philosophy without any experimental consequences. As for nonlocality, entanglement is a fundamentally nonlocal feature of quantum mechanics. There's no way to excise that from the theory, even if you can't exploit it to transmit information faster than light. I'd say calling it inherently nonlocal is entirely fair, that's a very different claim than that we can transmit information faster than light. ...which, as an aside, would not even in and of itself necessarily be problematic, closed timelike loops (for instance) are perfectly fine and good as long as you account for the fact that quantum interference will have very strong effects even at a macro scale in such geometries (the grandfather paradox gets interfered away, more or less, even if macroscopically unlikely things need to happen to end up with a reinforced consistent timeline).

VladKovac 10y ago

Quantum mechanics given a single world would have to be nonlocal based on bell's theorem. Only Many Worlds can give a local account which might work.

naasking 10y ago

> This is false, and a common misinterpretation of QM. We do not have any evidence of information travelling faster than the speed of light. It's actually not false as stated. The author didn't say information travels FTL. Copenhagen gives up realism to satisfy Bell's theorem, but is still non-local.