Timeline for Is the universe deterministic when looking backwards?
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| Jun 9, 2017 at 2:50 | comment | added | Bob Bee | Anyway, it is true as @Lemon says, that decoherence may not be interpreted as solving the measurement problem, just explaining how it happens. The observation may still include the degree of randomness to for instance where or when a particle emerges in a collision or interaction. Ie, some kind of interpretation of wave function collapse. Wikipedia has some kind of description of why one does not imply the other (i.e., decoherence does not 'explain' collapse), but if you read it it is still not clear ..... either way. I've read others over this past year and there's arguments both ways. | |
| Jun 9, 2017 at 2:36 | comment | added | Bob Bee | I assumed in my answer that time asymmetry, and running time backwards, the wave functions would still evolve deterministically. But then, going in that opposite direction of time it seems to me entropy would still increase. Yes, some particles would reassemble, but others would disperse, and it seems to me it would go to higher entropies in total. But I could be wrong. Hawking argues that psychological time, the time we feel, is always the thermodynamic arrow, as thinking and memory uses energy and produces heat. Anyway .....more next | |
| Jun 9, 2017 at 1:25 | comment | added | Warren Dew | But the weak force time asymmetry wouldn't make it nondeterministic, would it? Unless I'm misunderstanding your answer, if you "run it backwards" using time reversed physical rules, rather than normal forward time physical rules, you could in fact recover earlier states. | |
| Apr 13, 2017 at 12:39 | history | edited | CommunityBot |
replaced http://physics.stackexchange.com/ with https://physics.stackexchange.com/
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| Aug 1, 2016 at 8:34 | comment | added | lemon | From your link, "decoherence does not attempt to explain the measurement problem". | |
| Jul 31, 2016 at 19:31 | comment | added | Bob Bee | There are lots of writings and papers on this. The understanding has been sharpened by the whole idea of decoherence, in interactions with the environment. When you look at the system w/o considering it is interacting with the environment, it looks like it looses coherence, i.e., it becomes a mixed state. Consider the system and the environments, and the wavefunction for the whole is coherent and follows unitary evolution. When you break it up into the two each is entangled wiTh the other and is now a mixed state. The rest is philosophy. See en.m.wikipedia.org/wiki/Quantum_decoherence | |
| Jul 31, 2016 at 17:33 | comment | added | Bob Bee | Yes it is. Read real physics. I understand the confusion. Unitary means deterministic at the quantum level. The indeterminacy is when one tries to determine classical parameters like position and velocity. The wavefunction is the basic physics and evolves from deterministic quantum physics. The indeterminacy is trying to predict classical quantities which are, by quantum physics, probabilistic. That comes from the wave or field type nature of reality, according to quantum theory. I'll post a reference a little later today when I have more time. | |
| Jul 31, 2016 at 6:41 | comment | added | lemon | But that's not accepted mainstream physics... | |
| Jul 30, 2016 at 22:30 | comment | added | Bob Bee | My answer explains it. It is simply the interaction with the measurement apparatus. Include the wave function (pretty complex) of the two and there is no collapse. The evolution is always unitary, i.e. Causal, i.e. deterministic. | |
| Jul 30, 2016 at 21:42 | history | edited | Bob Bee | CC BY-SA 3.0 |
Added Hawking reference on soft hairs on Black Holes preserving the information so no paradox
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| Jul 30, 2016 at 21:34 | comment | added | lemon | Wait, physics is deterministic? The Schroedinger equation sure is, but as you go on to say, who knows about wave-function collapse? | |
| Jul 30, 2016 at 21:31 | history | edited | Bob Bee | CC BY-SA 3.0 |
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| Jul 30, 2016 at 21:23 | history | edited | Bob Bee | CC BY-SA 3.0 |
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| Jul 30, 2016 at 21:13 | history | answered | Bob Bee | CC BY-SA 3.0 |