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Collapse of wave function ,does it really happens?why?

Qmechanic
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user73034
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    There is no spoon... – user6760 Jan 08 '19 at 03:21
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    This is a hard question, about which whole books have been written. Have you poked around wikipedia for any relevant entries? recommend you have a look and then come back here if there's anything remaining that still puzzles you. -NN – niels nielsen Jan 08 '19 at 03:56
  • No. Collapse doesn't happen. Read "The Fabric of Reality" by David Deutsch chapter 2. – alanf Jan 08 '19 at 08:00

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Schlosshauer reviewed experimental data and concluded: "no positive experimental evidence exists for physical state-vector collapse" (Annals of Physics, 321 (2006) 112-149)

akhmeteli
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    The notion of a wave function collapsing isn't a dynamical thing that is an observable though – InertialObserver Jan 08 '19 at 03:24
  • @InertialObserver : The OP asks if collapse of wave function really happens, and my answer is there is no experimental evidence of that. – akhmeteli Jan 08 '19 at 03:30
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    Something happens though whether you call it a "collapse" or not. It is an easily observable effect, e.g. in a double slit experiment. There was a wave and now it is no more. Sounds evidence enough, no? – safesphere Jan 08 '19 at 07:36
  • @safesphere : No, there is no experimental evidence of deviations from unitary evolution. From the same article: "the universal validity of unitary dynamics and the superposition principle has been confirmed far into the mesoscopic and macroscopic realm in all experiments conducted thus far" – akhmeteli Jan 08 '19 at 07:59
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    Well, I hear you, but I didn't say anything about "unitary evolution". It seems that you are assuming that I've implied this and that in my comment, but I really haven't. All I'm saying, it is easily observable that a wave is killed by measurement. This is an experimental fact. The wave was there, but no more. You can call it "collapse" or "murder", whatever, but the wave is destroyed. – safesphere Jan 08 '19 at 08:20
  • @safesphere : Your phrase "a wave is killed by measurement" seems to mean that unitary evolution does not describe the act of measurement correctly. Unitary evolution does not describe any "wave killing". – akhmeteli Jan 08 '19 at 15:29
  • I think what @safesphere is saying is that something happens. It seems like you both are just differing in what you define as a "collpase". Safesphere recognizes this, but you do not. – BioPhysicist Jan 08 '19 at 20:31
  • @AaronStevens : If safesphere uses some homegrown definition of collapse, (s)he should have mentioned that. – akhmeteli Jan 09 '19 at 03:34
  • They did mention what they were considering to be a collapse. And I don't think it is "homegrown" at all. You are choosing to talk about collapse in a particular way. We are talking about collpase in general. – BioPhysicist Jan 09 '19 at 04:20
  • @AaronStevens : As far as I can see, safesphere defines collapse as "The wave was there, but no more" (with some variations). And, as I said, this contradicts unitary evolution, and there is no experimental evidence of violations of unitary evolution. If you find a different definition of collapse in safesphere's comments, please let me know. – akhmeteli Jan 09 '19 at 04:36