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Experiments spell doom for physical-collapse explanation of quantum weirdness

quantamagazine.org

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Re: Experiments spell doom for physical-collapse explanation of quantum weirdness

#291

Post by The5thElephant »

dilap wrote: post #289
The5thElephant wrote: post #281

Earlier quoted context omitted.

What is the point of such a theory besides trying to relieve us from the uncomfortable idea of many worlds? It is no better at explaining our perceived world than the simpler theory that consciousness exists across all these states and we aren't following some particular path through them. All states of conscious existence are being perceived and the perception of it being a coherent path through time is just an illu…

I am trying the reconcile the feeling of free-will we experience with its evident absence, per the theory. (Of course, you could also just say the feeling is an illusion.) I don't know if you can ever answer it one way or the other, because while consciousness certainly exists (again a fact I believe just because I feel it), it can't in any way influence the universe, at least per current theories of physics. On the…

Consciousness does influence the universe by being part of it. That's why we have the illusion of choice within the context of each moment rather than some meta-alien's perspective. But no it can't defeat determinism if that's what you meant.

I believe someone called that idea "quantum immortality" and I find it conceptually interesting if not somewhat terrifying. However it does seem like the inevitable conclusion of these ideas.

Re: Experiments spell doom for physical-collapse explanation of quantum weirdness

#292

Post by dilap »

The5thElephant wrote: post #291
dilap wrote: post #289

Earlier quoted context omitted.

I am trying the reconcile the feeling of free-will we experience with its evident absence, per the theory. (Of course, you could also just say the feeling is an illusion.) I don't know if you can ever answer it one way or the other, because while consciousness certainly exists (again a fact I believe just because I feel it), it can't in any way influence the universe, at least per current theories of physics. On the…

Consciousness does influence the universe by being part of it. That's why we have the illusion of choice within the context of each moment rather than some meta-alien's perspective. But no it can't defeat determinism if that's what you meant. I believe someone called that idea "quantum immortality" and I find it conceptually interesting if not somewhat terrifying. However it does seem like the inevitable conclusion o…

> Consciousness does influence the universe...

I'm not sure I'm following the argument. Let me phrase it this way: can you devise an experiment which will determine if a given entity is conscious?

> I believe someone called that idea "quantum immortality"

(Thanks for the term; I'd heared the idea expressed before, but not that phrase.)

Skimming the wikipedia page, I didn't find any of the counter-arguments to be particularly compelling.

So, while I'm not sure how deeply I believe it (simply because it feels very unintuitive -- and I'm definitely not about to try to kill myself to test it!†), I agree with you: it really does seem like the inevitable conclusion of these ideas; I also agree it's somewhat terrifying!

Especially when you consider that as time goes on, probably in the majority of the universes where you are alive, you are just barely alive, in great pain. The only consolation is that, perhaps, you'll still have enough awareness to think to yourself, "incredible that I haven't died yet -- I guess many-worlds really is true!"

(† Even if you are knock-down 100% convinced in quantum immortality, you probably still don't want to engage in wildly risky behavior or try to kill yourself -- because you will be killing yourself in a large number of universes, and causing a lot of pain to your loved ones in those universes. A similar argument could be applied to engaging in any sneaky behavior which would cause significant pain if discovered.)

Re: Experiments spell doom for physical-collapse explanation of quantum weirdness

#297

Post by cwillu »

infogulch wrote: post #234
jfengel wrote: post #92

Earlier quoted context omitted.

That's right: the "collapse" interpretation is an approximation. You can derive if from the MWI. We already know that the "worlds" separate and almost completely cease interacting. The interactions decrease to the order of "two to the power of Avogadro's number" almost immediately. The collapse interpretation rounds that to zero (at some arbitrary point). To make that more concrete you have to add a term to the equat…

If other 'branches' are still detectable, then they're probably detectable by more than one means; say, gravitationally . Could this be an explanation of dark matter? That is, dark matter is the sum of tiny gravitational interactions between many mostly-split branches of the wave function.

https://physics.stackexchange.com/questions/34993/reversing-...

“What actually happens in an experiment with electrons is kind of interesting. Since photons are massless they are easy to excite if they have long wavelength and hence low energy. Whenever an electron gets accelerated many "soft" (i.e., long wavelength) photons get emitted. But if the acceleration is weak, the photons have such long wavelength that they provide little information concerning which path, and interference is possible.

It is the same with gravitons. Except the probability of emitting a "hard" graviton (with short enough wavelength to distinguish the paths) is far, far smaller than for photons, and therefore gravitational decoherence is extremely weak.”

Re: Experiments spell doom for physical-collapse explanation of quantum weirdness

#299

Post by lamontcg »

glenstein wrote: post #267
lamontcg wrote: post #219

Earlier quoted context omitted.

But how does bifurcation of consciousness happen and how does it diagonalize the state so that we never see a cat in a complex linear superposition of |alive> and |dead> at the same time? 1/sqrt(2) |alive> + 1/sqrt(2) |dead> should be an equally valid outcome of the experiment via purely unitary evolution.

I feel like this is a pretty reasonable question being met with non answers. And it's a shame bc I think MWI is the frontrunner as of 2022, but this is a pretty significant question with Many Worlds I had not considered before.

Well I stole it from Roger Penrose (same Penrose as in the title article) which I think he presented in either The Emperor's New Mind or Shadows of the Mind. I think its the latter book which has more concrete arguments like this diagonalization argument. Also, the idea that collapse of the wave function could be mediated by virtual gravitons or something like that once the superposition state got sufficiently "massive" (which is the genesis of the ideas in the title article here).

Both are worthwhile if you like thinking about these kinds of things.

I've generally found nearly zero people who have read those books and of them most people poo-poo it all, and don't really engage with some of the issues presented in them.

He may be wrong. Einstein was also wrong about the EPR paper. But it seems like he's trying to engage with the problems and do science rather than just provide philosophical justification.

Re: Experiments spell doom for physical-collapse explanation of quantum weirdness

#300

Post by GoblinSlayer »

lamontcg wrote: post #219
GoblinSlayer wrote: post #196

Earlier quoted context omitted.

You end up in all branches and your consciousness ends up in all branches, where your mind works. MWI works best with physicalism, yep :) Maybe your copy in another branch even posted the same comment.

But how does bifurcation of consciousness happen and how does it diagonalize the state so that we never see a cat in a complex linear superposition of |alive> and |dead> at the same time? 1/sqrt(2) |alive> + 1/sqrt(2) |dead> should be an equally valid outcome of the experiment via purely unitary evolution.

The state and result of observation depends on the method of interaction, i.e. hamiltonian. In principle it's possible to observe the cat in a mixed state, we just don't use interaction that gives that result.
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