Theoretical physicist - Sabine Hossenfelder - has a blog site called "BackRe(Action)".Flannel Jesus wrote: ↑Fri Apr 15, 2022 8:06 am Well, I think you're being very much overly rejective of decoherence. You may not believe it, I don't expect you to accept that it's TRUE, but your overconfidence that decoherence over collapse isn't even a possibility worth considering, and that anybody who is considering so must be making a very foolish mistake, is I think unwarranted.
Decoherence IS an alternative to collapse.
https://en.wikipedia.org/wiki/Quantum_d ... nvironment.
It's not some crackpot idea I made up man haha. It's totally fine if your opinion is (And again, no, "decoherence" is not the answer.) But it seems more like you're demanding I reject decoherence as the answer, rather than just stating that as your own personal position. I don't need you to demand anything of me.Decoherence has been used to understand the possibility of the collapse of the wave function in quantum mechanics. Decoherence does not generate actual wave-function collapse. It only provides a framework for apparent wave-function collapse, as the quantum nature of the system "leaks" into the environment. That is, components of the wave function are decoupled from a coherent system and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. With respect to the measurement problem, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the "realization" of precisely one state in the "ensemble".
The following is copy and pasted from a short exchange I had with Sabine last year on this very subject (slightly altered by adding boldings and size adjustments to certain portions) (Here's the link: http://backreaction.blogspot.com/2021/0 ... you%20have)
It's from her blog post titled: "Schrödinger’s Cat – Still Not Dead"
I extracted the following quote from Sabine's OP:
To which I responded with:Sabine wrote: "...As you have undoubtedly noticed, cats are usually either dead or alive, not both. The reason is that even tiny interactions with a quantum system have the same effect as a measurement, and large objects, like cats, just constantly interact with something, like air or the cosmic background radiation. And that’s already sufficient to destroy a quantum superposition of a cat so quickly we’d never observe it..."
To which Sabine replied:Keith D. Gill wrote: Sabine, you have taught me to never make any assumptions about the things you say. Nevertheless, out of curiosity, are you alluding to "decoherence" in the above quote?
If not, then please say so. But if you are, then according to Wiki:Now you may have had something else in mind, but does the fact that the Wiki quote states that decoherence..."...Decoherence was first introduced in 1970 by the German physicist H Dieter Zeh and has been a subject of active research since the 1980s. Decoherence has been developed into a complete framework, but it does not solve the measurement problem, as the founders of decoherence theory admit in their seminal papers....Decoherence does not generate actual wave-function collapse...."
"...does not generate actual wave-function collapse..." thus, "...does not solve the measurement problem..."
...have any bearing on what you said about the alleged collapse that occurs simply by cats interacting with "air" or "cosmic radiation"?
After all, isn't it a fact that certain interpretations of quantum mechanics suggest that the "unmeasured" cosmic background radiation would itself exist in a state of superposition that would, in theory, be entangled with the "unmeasured" cat's superposition, and thus simply form a larger and more complex wavefunction that contains no inherent means for collapsing itself?
Again, decoherence "...does not generate actual wave-function collapse..."
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Forgive me, Flannel Jesus, for my shameless appeal to authority, but I just wanted to show you that I too have referenced the Wiki article on "quantum decoherence" in these sorts of debates. However, in my case, it was to point out how decoherence cannot be used as the reason for the collapse of the wave function.Sabine wrote: "Yes, it refers to decoherence. It is correct that decoherence does not collapse the wave-function. I didn't say it does."
And, of course (as always), that doesn't mean I cannot be wrong about these mysterious issues. So, you are absolutely correct to point out that I have no right to demand that you reject your own position on decoherence and replace it with mine.
As an amusing sidenote, notice how Sabine stated that...
Yet, if you read the initial quote from her at the top of this post, she clearly states that,...Sabine wrote: "...It is correct that decoherence does not collapse the wave-function. I didn't say it does..."
...of which she admitted was a reference to decoherence. She then went on to say...Sabine wrote: "...even tiny interactions with a quantum system have the same effect as a measurement, and large objects, like cats, just constantly interact with something, like air or the cosmic background radiation...."
Anyway, based on other conversations I had with her on that site, if I would have pressed her on what seemed to be a contradiction, she probably would have cussed at me like a sailor and told me how confused she thinks I am.Sabine wrote: "...And that’s already sufficient to destroy a quantum superposition of a cat so quickly we’d never observe it..."
(Continued in next post)
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