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Fluid Tests Hint at Concrete Quantum Reality

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Re: Fluid Tests Hint at Concrete Quantum Reality

#111

Post by DavidPlumpton »

danbruc wrote: post #51
Sharlin wrote: post #42

Earlier quoted context omitted.

The Standard Model does not concern itself with the various interpretations of quantum mechanics. It can, as of now, neither verify or falsify any of the interpretations which, consequently, are not scientific theories or even hypotheses, but firmly on the side of philosophy of physics. The interpretations are attempts to answer why Nature works as it does, within the framework of the Standard Model which only appear…

IMHO the many worlds interpretation is one of the least appealing interpretation - millions of millions of millions of universes for nothing. What do you think about the following similar argument? Why are the laws of physics and the physical constants the way they are? There is a universe for every possible set of laws and constants and our universe just happens to be compatible with life. You can just render almost…

What's more likely? That quantum interference appears because many worlds perpetually exist, or because they seem to exist but somehow don't, or because they sometimes briefly come into existence, hang around for a bit and then randomly collapse breaking all sorts of laws (Liouville thereom, CPT invariance etc.)?

Many Worlds is much tidier than all the alternatives.hh

Re: Fluid Tests Hint at Concrete Quantum Reality

#112

Post by alphydan »

spacehome wrote: post #87
danbruc wrote: post #63

Earlier quoted context omitted.

But there is an important difference - you can observe the other stuff in our universe and therefore know that we are not (exceptionally) special in our universe. Other universes are usually per definition completely outside of our reach, as hard to grab as a god or Russell's teapot.

Well, they're not completely outside our reach. Interference between our worlds and nearby ones is very testable, and the reason the theory exists.

That makes it out of reach. You cannot falsify the many-worlds-interpretation simply with interference. All other interpretations make the very same predictions.

Re: Fluid Tests Hint at Concrete Quantum Reality

#113

Post by alphydan »

GregBuchholz wrote: post #4

I've liked: Clearing up Mysteries - The Original Goal http://bayes.wustl.edu/etj/articles/cmystery.pdf " ...we must keep in mind that Einstein's thinking is always on the ontological level; the purpose of the EPR argument was to show that the QM state vector cannot be a representation of the "real physical situation" of a system. Bohr had never claimed that it was, although his strange way of expressing himself often…

Could it be that you're not prepared for "What is really happening"? It seems like you'r expecting that QM's unintuitive properties will go away with a better theory.

They may, but it doesn't have to be that way. It may just be that reality at that scale is not made of trajectories, balls, and simple causality. As evolved monkeys with 5 senses we are used to intuitive concepts like continuity, predictions, trajectories, objects.

Now imagine a world 1,000,000 times smaller. Will it behave, look and feel the same way? Maybe. Let's shrink it 10,000 times again. Now we are at the size of an atom. Does the landscape look familiar? It may be so unfamiliar that trying to shoehorn our monkey intuitive world-view is helpless.

No objects, no concept of position, no matter as "substance occupying a space", no limitations regarding being in different places at the same time. It may well be that things are so different that it's best described as a mathematical abstract world ... because no intuitive structures and behaviours exist there. (Heisenberg has some interesting correspondence with Bohr on the matter)

It would be like trying to search for Mario inside your nintendo. Mario and his physics only live as abstract equations. Taking apart the computer will not show us what Mario's flesh is made of. The analogy can't be taken too far of course, because there is no known "chip" besides the mathematical structure of the universe.

There is plenty of research on quantum reality (from one of my colleagues, for eg. http://arxiv.org/abs/0709.1149), but it may turn out that there isn't an easy "particle does X when it enters Stern-Gerlach". The concept of particle is probably completely inadequate.

Re: Fluid Tests Hint at Concrete Quantum Reality

#114

Post by thedufer »

X4 wrote: post #65
thedufer wrote: post #37

Earlier quoted context omitted.

I'm skeptical, if only because this should be a big deal and hasn't gotten much press. > We're able to set the spin (rotational direction) of these particles in a predetermined state, verify this spin and subsequently read out the data. This is terribly unclear. I don't have access to the article - maybe its better explained there? The problem with using quantum entanglement for information transfer is that you can't…

Paper in short: http://download.repubblica.it/pdf/2014/scienze/science-xpres... Paper in full: http://arxiv.org/abs/1404.4369 To the physicists among the us, please share your opinion on the paper with the rest of us. It's not easy to digest the paper. The finding is not only going to change finance, but also the whole data economy will speed up. Now 'Quants' can be located anywhere and everyone has can enjoy same ad…

> Alice sends the outcome via a classical communication channel to Bob, who can then recover the original state by applying the corresponding local transformation.

This seems to be the key point - there is absolutely no FTL information transfer going on, which is pretty much what I expected. As I said before, it would've been much bigger news if there was. The press article was clearly written by someone who didn't understand what was going on (or was intentionally deceitful, but that seems unlikely).

Re: Fluid Tests Hint at Concrete Quantum Reality

#115

Post by thedufer »

jostylr wrote: post #54
thedufer wrote: post #25

Earlier quoted context omitted.

Its certainly accessible, but I'm not sure how much I trust the authors to understand what they're talking about after point 3. > But very often the conclusion that is drawn from this observation is that our _knowledge_ about the path followed by the electron causes the interference pattern to disappear. Although we couch the idea in terms of "knowledge", the usual meaning of that word is not what anyone thinks is ac…

That FAQ is generated by the students of a very trustworthy group. Students typically setup strawman when explaining things. Look more to the source. Also, they are trying to argue against a theory which no one wants to fully specify. So they have to come up with something definite. And as soon as they do, the other side says "Strawman!" And then proceeds, as you have just done, to refuse to give a definite theory. A…

There is a range of possibilities of what might cause a wavefunction collapse, and the constructed strawman is nowhere near that. It would be like if we claimed the speed of light was 3.2e8 +/- 5e7 m/s and someone decided our whole theory was bunk because the speed of light is obviously faster than 100 m/s. Well yeah, it is, but there's no contradiction here.

"if the particle interacts with something in such a way that its position suddenly becomes deducible, then it collapses" would be a theory in the range of possibilities. It would be much more convincing to argue against something like that.

Re: Fluid Tests Hint at Concrete Quantum Reality

#116

Post by eli_gottlieb »

DavidPlumpton wrote: post #111
danbruc wrote: post #51

Earlier quoted context omitted.

IMHO the many worlds interpretation is one of the least appealing interpretation - millions of millions of millions of universes for nothing. What do you think about the following similar argument? Why are the laws of physics and the physical constants the way they are? There is a universe for every possible set of laws and constants and our universe just happens to be compatible with life. You can just render almost…

What's more likely? That quantum interference appears because many worlds perpetually exist, or because they seem to exist but somehow don't, or because they sometimes briefly come into existence, hang around for a bit and then randomly collapse breaking all sorts of laws (Liouville thereom, CPT invariance etc.)? Many Worlds is much tidier than all the alternatives.hh

Actually, I'd say the "illusion" option is the simplest and tidiest. It is more likely that we interpret a complicated reality from incomplete information than that reality truly is complicated.

Re: Fluid Tests Hint at Concrete Quantum Reality

#117

Post by [deleted] »

sriku wrote: post #102
msane wrote: post #101

Earlier quoted context omitted.

The significance is that this is a model of a special, alternate formulation of quantum mechanics called Pilot-wave Theory.

pwt is an interpretation. All interpretations of QM share the same mathematics .. or effectively the same maths. Different "interpretations" cannot produce different predictions in experiments. So using an experiment designed to emulate pwt (which afaik violates special relativity) can only say one thing possibly - that if we find it convenient to think in this way in some limited cases of quantum mechanics, we may d…

[deleted]

Re: Fluid Tests Hint at Concrete Quantum Reality

#118

Post by msane »

sriku wrote: post #102
msane wrote: post #101

Earlier quoted context omitted.

The significance is that this is a model of a special, alternate formulation of quantum mechanics called Pilot-wave Theory.

pwt is an interpretation. All interpretations of QM share the same mathematics .. or effectively the same maths. Different "interpretations" cannot produce different predictions in experiments. So using an experiment designed to emulate pwt (which afaik violates special relativity) can only say one thing possibly - that if we find it convenient to think in this way in some limited cases of quantum mechanics, we may d…

Wow!

Re: Fluid Tests Hint at Concrete Quantum Reality

#119

Post by msane »

sriku wrote: post #102
msane wrote: post #101

Earlier quoted context omitted.

The significance is that this is a model of a special, alternate formulation of quantum mechanics called Pilot-wave Theory.

pwt is an interpretation. All interpretations of QM share the same mathematics .. or effectively the same maths. Different "interpretations" cannot produce different predictions in experiments. So using an experiment designed to emulate pwt (which afaik violates special relativity) can only say one thing possibly - that if we find it convenient to think in this way in some limited cases of quantum mechanics, we may d…

> All interpretations of QM share the same mathematics .. or effectively the same maths.

No they do not.

> Different "interpretations" cannot produce different predictions in experiments.

Yes they do.

Re: Fluid Tests Hint at Concrete Quantum Reality

#120

Post by prutschman »

SilasX wrote: post #99
spacehome wrote: post #88

Earlier quoted context omitted.

I would never say instead of. Read whomever you like; read them all. Though, I would suggest that anyone who still takes Copenhagen seriously really needs to digest that sequence. Eliezer is a smart guy with great insights into how to think about questions. His "position of authority" is that he writes in a way that's clear and conveys meaningful novel insights. If you think that only Ph.D.s have insights worth readi…

>>And why should we read Yudkowski instead >I would never say instead of. When you recommend something, you're implicitly advocating that it be read in preference to other works on the matter. It makes no sense to say "I recommend this, but it's no better than anything else."

"I recommend this. Reading it is better than not reading it, and you may not have been aware of its existence."

The recommender is in no position to know whether your next-best alternative was reading another work on the subject or reloading hacker news or taking a nap.

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