Experiments spell doom for physical-collapse explanation of quantum weirdness • Hacker News Board

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

#251

Post by ravi-delia » Sat, Oct 22, 2022, 2:40 AM UTC

jobs_throwaway wrote: post #95

ravi-delia wrote: post #47

Earlier quoted context omitted.

Or- and hear me out with this one- they prefer an explanation which follows naturally from existing experiments and doesn't require a hacked together non-linear irreversible operation which occurs only under bizarre conditions exactly when needed to patch over experimental results. No one in the whole world cares if the universe is deterministic or not, but collapse is embedded in an entirely deterministic system. MW…

> No one in the whole world cares if the universe is deterministic or not lol

OK other than the several holy wars and church schisms and most of the physicists of the early 1900s including Einstein. And quantum-woo obsessed people on the internet. The point is that all the quantum stuff still adds up to mostly deterministic classical physics. Maybe only quantum physicists get to have free will, so long as they make decisions based on the exact results of their experiments?

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

#252

Post by ravi-delia » Sat, Oct 22, 2022, 2:41 AM UTC

GoblinSlayer wrote: post #188

tsimionescu wrote: post #98

Earlier quoted context omitted.

Actually, if you eliminate collapse entirely as a non-linear operation, then you have a new huge problem for QM: there is plenty of non-linearity in the universe (e.g. double pendulum experiments, not to mention GR), and QM predicts that there shouldn't be any non-linearity at all, if you eliminate wave function collapse/the Born postulate.

Hmm... is de Broglie wave linear? Trigonometric functions don't look very linear to me.

Ahh, linear in the differential equations sense, not the affine function sense. Trigonometric functions are quite linear- they decompose into a basis! That's why, for instance, Fourier transforms are useful for more than signal processing.

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

#253

Post by c1ccccc1 » Sat, Oct 22, 2022, 3:03 AM UTC

throwaway81523 wrote: post #249

c1ccccc1 wrote: post #212

Earlier quoted context omitted.

Many worlds is absolutely testable, since if we observe collapse in even a single one of these experiments then that completely falsifies many worlds. If one of these experiments discussed in the article had actually observed a collapse, then I have no doubt we'd be seeing headlines like "many worlds theory disproven", and Nobel prizes for the physicists involved. It would be the biggest discovery in physics for deca…

We "observe" collapse all the time, and can calculate the probabilities of the different possible collapsed states of a not-yet-observed superposed or entangled state using the Born rule. What we don't know, and can't tell, is whether we have seen an "objective collapse" (we live in just one universe, that undergoes a discontinuous change at the time of measurement) or in something like MWI. That is question for phil…

I agree that's it's possible to create objective collapse theories that are arbitrarily difficult to falsify, but the difference between objective collapse and regular old decoherence due to interaction with the environment has experimentally measurable implications. In particular, if you expect a certain probability of objective collapse in a certain period of time, then do an experiment with a coherence time longer than that, while keeping your system carefully isolated from interaction with the environment. Then if the wavefunction collapses anyway, that would prove objective collapse and disprove many worlds.

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

#254

Post by richardfey » Sat, Oct 22, 2022, 3:08 AM UTC

> If there is indeed a background perturbation that provokes quantum collapse [...] then all particles will be continuously interacting with this perturbation, whether they are in a superposition or not.

This reminds me of how our own heart's peacemaker works.

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

#255

Post by masteranza » Sat, Oct 22, 2022, 3:42 AM UTC

thrown_22 wrote: post #241

masteranza wrote: post #226

Earlier quoted context omitted.

Just saying something twice doesn't make it true. The "weird" thing you were perhaps referring too starts at very beginning of quantum mechanics framework. The Born rule is just a "conversion" of predictions of quantum framework to our classical language. The only option you have is to reject quantum mechanics as a whole and not try to patch it - because this clearly will not work.

The weird thing would be discontinuities showing up in wave function evolution without putting them there with the potential energy functions. In the few cases where we can get analytical solutions there are no discontinuities that look anything like wave function collapse. You're whole thesis rests on the fact that this should fall out when we put 6e23 particles together for reasons. So far we've not managed to simu…

I hope that you read this with a scientific attitude, i.e., critical, but open to the fact that not only your position is wrong, but also the unproductive enterprise of solving "the measurement problem" is wrong.

What I'm trying to explain to you is that: 1) The wavefunction is only the DESCRIPTION of the underlying phenomena. 2) Within this description everything, and I mean ::everything::, evolves unitarily. No exceptions ever. 3) Whenever you decide to measure, i.e., probe the microscopic system with an object that is not within your quantum description, that is you know that it's huge, but have no details about all the phase/amplitude information you're destined to average/trace over the unknown states. This can be done symbolically (as in my first post here) and shown to always give probabilities in the reduced density matrix. That's always what we're left with in case of a large system outside of our description interacting with a small system within our description. On the other hand if you put a small quantum system, with another small quantum system (say two particles), there's no need to trace/average/apply the born rule immediately because your description can be complete both in principle and in practice. You can just unitarily evolve the system for as long as you wish/can compute for. However sooner or later you'll want to measure, because ultimately that's what physics is all about - verifying your predictions with experiment - and you go back again to small vs big, because that's the only way we, humans, can perceive this microscopic reality - through probing. The result will be completely analogous to the one before, the only change being that you'll now be able to predict probabilities of a two-particle system.

If you're familiar with electrodynamics it's quite similar there, but here it's brought to another level with the probabilistic interpretation. What are the similarities? You can have your complete description with the four-potential, about which you know, from the Aharonov-Bohm effect, carries more information than electric/magnetic fields alone although we only measure fields not the electric/magnetic potentials. The potentials were the side product of the formalism that turned out to have real consequences. Similarly as we learned the importance of the wavefunction/phases in the description, even though we only measure probabilities.

About the curse of dimensionality, the only thing I have to add is, that's true. We have a precise way to describe what is going down there but it's insanely expensive to simulate in all detail. That's still a lot to be happy with in my opinion.

Also, if you feel uneasy with wavefunctions which have the status of descriptions of reality, go and study classical field theory in which the fields are to be thought of as real physical entities, go step deeper and you're in quantum field theory in which you deal with descriptions again. Would a theory in which we deal with "real physical entities" be better than that of "descriptions"? I'd say, the hell with it. Go with whatever works best, not whatever fits your preconceived notions of reality.

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

#256

Post by astrange » Sat, Oct 22, 2022, 3:54 AM UTC

simonh wrote: post #56

vpfaulkner wrote: post #36

From a layman’s point of view, it seems like we grasping at straws when it comes to these thorny quantum questions. Is fair to say, for example, that we are about as clueless as our ancestors were with the bubonic plague? To a non-expert it can be difficult to separate which theories lay on solid ground and which theories are highly speculative.

QM is hard to visualise, but we have extremely sophisticated equations and principles for determining how quantum systems will evolve, and can engineer complex functioning systems using that knowledge. For example transistors only work because we understand QM well enough to precisely engineer the energy level state behaviour of electrons in semiconductors. It would be like accidentally discovering antibiotics during…

That applies to a lot of medicine right now - we don't know how Tylenol or antidepressants work, and Semmelweiss's invention of handwashing was rejected because he couldn't explain why it was working.

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

#257

Post by astrange » Sat, Oct 22, 2022, 4:02 AM UTC

kryptiskt wrote: post #20

bottlepalm wrote: post #13

I remember something about super determinism being a possible answer to this. Do these results increase the likelihood of that?

No, none of the other explanations predicts anything like this. The theories that fell here predicted physical effects that went beyond standard quantum mechanics. The others are playing it safe and staying unfalsifiable.

Some superdeterministic theories are testable. Some of them aren't, or say things like experiments aren't capable of proving anything in the first place because the universe doesn't obey rules.

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

#258

Post by throwaway81523 » Sat, Oct 22, 2022, 4:30 AM UTC

c1ccccc1 wrote: post #253

throwaway81523 wrote: post #249

Earlier quoted context omitted.

We "observe" collapse all the time, and can calculate the probabilities of the different possible collapsed states of a not-yet-observed superposed or entangled state using the Born rule. What we don't know, and can't tell, is whether we have seen an "objective collapse" (we live in just one universe, that undergoes a discontinuous change at the time of measurement) or in something like MWI. That is question for phil…

I agree that's it's possible to create objective collapse theories that are arbitrarily difficult to falsify, but the difference between objective collapse and regular old decoherence due to interaction with the environment has experimentally measurable implications. In particular, if you expect a certain probability of objective collapse in a certain period of time, then do an experiment with a coherence time longer…

I thought an objective collapse theory was one where the observation (whatever that is) causes the collapse. An observation is necessarily an interaction with the system, where the observer is part of the environment. So if the system is that isolated from the environment, the collapse or lack of it can't be observed. I didn't think it meant the collapse happens after some amount of time like radioactive decay, even without an observation (interaction). Maybe I'm wrong.

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

#259

Post by TEP_Kim_Il_Sung » Sat, Oct 22, 2022, 5:08 AM UTC

pdonis wrote: post #210

TEP_Kim_Il_Sung wrote: post #189

Earlier quoted context omitted.

You are all the "copies", and, under certain conditions, can experience all their observations. Think of yourself more as an aspect of a multifaceted being experiencing the universe through you.

> under certain conditions, can experience all their observations What conditions are these?

Practice lucid dreaming, so you can maintain a semi-awake meditative state. Practice remembering your dreams -some of them are memories from other aspects like you, others are your subconscious communicating through symbols and situations. Practice asking questions, dreaming, and remembering. Practice reaching the semi-awake meditative state from the awakened end of your day. Realize, what you think of as your body, is the 4D sensory organ of your hyperdimensional self, maintain meditative state, and open your other eyes. The effect is a lot like the collage view of regular stereoscopic vision, except out of the immediate overton-window of aspects of yourself similar enough to you.

Getting to that point can take several years. A quicker option seem to be drugs, based on conversations I had with friends, but I never wanted to artificially taint my perception, so I did it the hard way. My findings are that while there is no fate, there exist enough aspects in universes similar enough to yours, but perhaps chronically shifted, that you can learn from their mistakes. This is known as instinct, "guardian angels", premonition, deja-vue, etc. Good luck.

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

#260

Post by omnicognate » Sat, Oct 22, 2022, 6:02 AM UTC

thrown_22 wrote: post #243

omnicognate wrote: post #229

Earlier quoted context omitted.

The theory made predictions that could be - and have been (read the article) - shown false. Do you have some other definition of falsifiability?

If you read the article there is still plenty of room for those effects to hide in, just like there was before these experiments were done. No one has changed their minds because of this.

You mean the bit where he's working on a version of Orch OR that doesn't cause bremsstrahlung? That's coming up with a new theory. You can always go away and change the theory. This isn't one of those overparameterised theory generators that can trivially explain every possible observation. He will have to materially change it to accommodate this.

And why shouldn't he explore what changes would be needed to accommodate the new evidence? That's not the behaviour of a crank convinced his theory must be right regardless of any evidence. It's just a natural thing to think about when a theory is falsified. He's never described Orch OR as anything more than speculative.

And frankly, what else would you expect him to do? He's 91. It's astonishing that he's still doing this sort of work at all. He's hardly going to start from scratch with a completely fresh theory at this stage, although if anybody could it would be Penrose.