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

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

#81

Post by didericis » Fri, Oct 21, 2022, 2:29 PM UTC

telmo wrote: post #52

wongarsu wrote: post #12

Earlier quoted context omitted.

To be fair, the Copenhagen interpretation doesn't really fit today's world view. We have largely moved away from viewing humans or "consciousness" as something special, so the notion that an observer collapses the wave function just seems weird now. "Many worlds" or "the wave function never collapses, you are in a superposition" both make much more sense with how we currently view the world

I also prefer the Many Worlds interpretation and I do think that it is gaining popularity in relation to Copenhagen, but I'm not sure what you mean by "today's world view". And who is this "we" that you write about? I prefer Many Worlds because it is a simpler explanation, so I follow Occam's razor. That's it. Consciousness and the existence of qualia remains a fundamental mystery. There is something definitely speci…

Exactly. A related deep millennia old observation is that no one has actually seen the real world. Everything we’ve ever experienced has been filtered through our minds. Every experiment, every measuring device, every meticulously crafted model of reality… it is all inescapably limited by what we are able to experience.

One could and many have argued that the reality we’ve been observing and operating in is consciousness. The “real” world could be entirely different and largely inaccessible.

These kinds of thought exercises don’t have much practical utility, apart from one very important feature; they humble you. At the end of the day we don’t fundamentally know anything, and should always recognize that at its most basic root level, everything we do is an educated guess. A fundamentally skeptical and curious outlook that acknowledges our perceptual limitations is how we got all of the sophisticated models of very difficult to observe phenomenon in the first place. If we want to continue to get the best understanding of whatever it is we’re experiencing, I think it’s very important to stay humble and ensure our knowledge is treated as a hard earned set of well reasoned guesses rather than unquestionable dogma. 99.9% of objections to well established ideas and models might be a waste of time entertaining, but you never know what might turn out to be the seeds of a whole new universe of understanding that invalidates huge swaths of our existing corpus of knowledge.

Most of what I’m saying here is probably obvious to a lot of readers, and I don’t think anyone in this thread is being particularly arrogant or dogmatic, but I think it’s worth reiterating. If people who understand the limits of knowledge aren’t constantly emphasizing the fact that we don’t know what we don’t know, that creates fertile ground for both dogmatic assertions and unreasonable skepticism, and I think a huge amount of dysfunction in the culture at large is explained by insufficient well calibrated humility amongst otherwise very intelligent people who set an example for others.

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

#82

Post by im3w1l » Fri, Oct 21, 2022, 2:35 PM UTC

gus_massa wrote: post #26

im3w1l wrote: post #5

In true collapse-of-the-gaps style, what if collapse happens when an entangled system becomes so large that the edges of it are outside of each others event horizons due to cosmic inflation?

If you have only one particle of the entangled pair, you can't do any experiment to check if they pair is still entangled or someone else has done something to the other particle and broke the entanglement. Someone else is not necessarily a person. May be a device or just a brick. In a common case, when you measure your particle you get 50% "yes" and 50% "no". So if you have a stream of particles that are one half of…

Dang I low key have a problem here because I already mentioned it was a joke and gave the same explanation, but because this is the top reply and the comments both show n-hours ago it looks like I walked back my statement in response, and I think it's fair to say that this is why the original comment got a down vote and ended up at the bottom.

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

#83

Post by naasking » Fri, Oct 21, 2022, 2:37 PM UTC

sebastialonso wrote: post #65

herdcall wrote: post #54

Earlier quoted context omitted.

Check out "superdeterminism," first proposed by Bell (of Bell's inequality fame) himself and currently being vigorously pursued by Sabina Hossenfelder. There is no "collapse" per se according to this model and everything is really classical with hidden variables, and the entanglement comes because everything shared the same origin (the big bang). A very fascinating and in my opinion the best explanation, though it's…

Is superdeterminism even falsifiable?

Is Many-Worlds even falsifiable?

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

#84

Post by superposeur » Fri, Oct 21, 2022, 2:41 PM UTC

iainmerrick wrote: post #58

herdcall wrote: post #54

Earlier quoted context omitted.

Check out "superdeterminism," first proposed by Bell (of Bell's inequality fame) himself and currently being vigorously pursued by Sabina Hossenfelder. There is no "collapse" per se according to this model and everything is really classical with hidden variables, and the entanglement comes because everything shared the same origin (the big bang). A very fascinating and in my opinion the best explanation, though it's…

I have never fully understood that idea, even after reading Hossenfelder's posts about it. The idea that there's a "block universe" and everything is predetermined is comprehensible, sure; but what's the exact mechanism by which Bell's inequality is violated in experiments? Doesn't that require the universe to have been carefully set up to look as if it's acting in a weird non-local way, on an experiment-by-experimen…

Agreed — superdeterminism is not so much a theory as a theory-for-a-theory at this stage (a vague guess at the form such a theory might take).

It is a sign of the much greater maturity of the physical collapse models that their parameters can be constrained by experiment. The ability to be constrained is a good sign, not a bad one.

I love John Preskill’s standard nod to superdeterminism in his writings: without mentioning it by name he says “I leave it up to the reader to decide how seriously to take this possibility” (get it?)

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

#85

Post by bee_rider » Fri, Oct 21, 2022, 2:45 PM UTC

ravi-delia wrote: post #45

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.

That would not be fair, though it's understandable why a layman might feel that way. The fact is, most physicists don't particularly feel the need to have an explanation for that kind of thing. We have the math, and most people agree on how to use it to make very accurate predictions. Collapse was always a little silly, but there are other possibilities as to why you'd get that kind of effect just from wavefunctions.

"It's only a model" Patsy says, but then they cut to a whole big song and dance routine, so it must be a pretty good model. Or course it is unsurprising that Monty Python's Holy Grail would provide deep physics insights, they were a pretty clever bunch.

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

#86

Post by naasking » Fri, Oct 21, 2022, 2:46 PM UTC

iainmerrick wrote: post #58

herdcall wrote: post #54

Earlier quoted context omitted.

Check out "superdeterminism," first proposed by Bell (of Bell's inequality fame) himself and currently being vigorously pursued by Sabina Hossenfelder. There is no "collapse" per se according to this model and everything is really classical with hidden variables, and the entanglement comes because everything shared the same origin (the big bang). A very fascinating and in my opinion the best explanation, though it's…

I have never fully understood that idea, even after reading Hossenfelder's posts about it. The idea that there's a "block universe" and everything is predetermined is comprehensible, sure; but what's the exact mechanism by which Bell's inequality is violated in experiments? Doesn't that require the universe to have been carefully set up to look as if it's acting in a weird non-local way, on an experiment-by-experimen…

We had a recent thread about an article from Tim Palmer who has a good take on this:

https://news.ycombinator.com/item?id=33223391

The idea is that the natural laws are fractal, which when mapped out trace many state space configurations. But with a fractal there are always gaps in state space that remain no matter how much you zoom in or out; fractals preserve certain structural invariants at all scales.

So the idea is that counterfactual reasoning sometimes fails in a fractal universe, because statistical independence no longer works as a general rule (your counterfactual could lie in one of those gaps). He first published this idea in 2009 under the name "invariant set postulate":

https://en.wikipedia.org/wiki/Invariant_set_postulate

His paper with Hossenfelder is also a good overview:

https://www.frontiersin.org/articles/10.3389/fphy.2020.00139...

Superdeterminism gets an unnecessarily bad rap.

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

#87

Post by naasking » Fri, Oct 21, 2022, 2:49 PM UTC

im3w1l wrote: post #41

criddell wrote: post #24

Earlier quoted context omitted.

> My feeling is that Everett's "many worlds" interpretation is the clear favorite But what are the worlds? My feeling is that Max Tegmark has it right. Everything is mathematics.

We can detect their presence because they cause interference with our own.

Circular. You have to already accept many worlds to take this as evidence of worlds. You can argue for Many-Worlds on grounds of parsimony and clarity, but that's it.

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

#88

Post by tshaddox » Fri, Oct 21, 2022, 2:51 PM UTC

naasking wrote: post #83

sebastialonso wrote: post #65

Earlier quoted context omitted.

Is superdeterminism even falsifiable?

Is Many-Worlds even falsifiable?

David Deutsch seems to think that a general intelligence running on a quantum computer ought to be able to observe itself existing in parallel worlds if many-worlds is true.

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

#89

Post by naasking » Fri, Oct 21, 2022, 2:54 PM UTC

tshaddox wrote: post #88

naasking wrote: post #83

Earlier quoted context omitted.

Is Many-Worlds even falsifiable?

David Deutsch seems to think that a general intelligence running on a quantum computer ought to be able to observe itself existing in parallel worlds if many-worlds is true.

I'm skeptical that Deutsch actually meant that, but even smart people have crazy ideas.

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

#90

Post by fallingfrog » Fri, Oct 21, 2022, 2:55 PM UTC

lupire wrote: post #9

dzdt wrote: post #4

There is an often-repeated statement that different quantum mechanical theories are equivalent. This is an over-simplification. Is wave function collapse is a real thing or just an approximation of what happens when a large system is entangled? Some smart people have tried to make theories where wave function collapse is a real thing. These new experiments are working to rule out those ideas. My feeling is that Evere…

Disproving some form of measurable wave function does not provide evidence for MWI, which is unmeasurable and untestable nearly by definition.

Well, the thing is that the MWI is actually simpler than all the other interpretations, because it simply removes the idea of wave function collapse entirely. Any theory involving wave function collapse is adding something extra to quantum physics that can't be demonstrated experimentally.

Because we live in the macro world, it feels like a single unitary reality is simpler, but actually, the MWI makes fewer assumptions. So I would turn that around and put the burden on the other theories to show that collapse is real, the default position should be MWI.