"Quantum untanglement"

[gcol]

In this week's NewScientist (3rd Nov.) There is an article titled "quantum untanglement", by one Mark Buchanan. (not, I believe the same person who comes up as a Baptist minister!). He appears to be a phd and sometime editor of this magazine and Nature. I can provide no links, because it requires a subscription which I do not have.

 

The reason I hesitantly bring this up, is that my knowledge of the way things are, and the way they might be in the future, is through such "popular Science" articles. They feed my curiousity and fuel my imagination in an easy to assimilate maths-lite way. (As of course do also many of the threads in this august forum;) ).

 

I hope that among the readers of this forum are many who have read this article and can give me their opinions on the new ideas and theories therein explored.

 

I fear, though, that without a link there may be little response.

 

But a small random quote to whet appetites, and possibly hook Martin: "Lee Smolin of the perimeter institute in Waterloo, Canada, for one, doubts that physicists can really make headway building a true theory of quantum gravity and spacetime before making some serious revisions to quantum theory itself. The inability of theorists to extend quantum theory to the entire universe, he suggests, may imply that it only works for parts of the universe, as an approximation of some deeper reality." (My italics.)

 

 

Two more quotes from the closing paragraph, that I find delicious: "Sudenly it's more acceptable to challenge the dogma and to look for a more fundamental simpler theory" and "Now lots of people are looking at the standard ideas of physics through new eyes" (Philip Pearle, ex Hamilton College, NY.)

 

There is also some comment on work by 'thooft on a deterministic phenomenon that lies below quantum theory an is (deliberately?) ignored by it.

[swansont]

Two more quotes from the closing paragraph, that I find delicious: "Sudenly it's more acceptable to challenge the dogma and to look for a more fundamental simpler theory" and "Now lots of people are looking at the standard ideas of physics through new eyes" (Philip Pearle, ex Hamilton College, NY.)

 

I haven't read the article, but the implication of this quote is wrong. QM was never dogma; it works in explaining how nature behaves, and for that reason it won't be scrapped. Just like F=ma and all of classical physics is still around. If someone finds a more basic description of nature, it had better predict all of the quantum effects we see, since that's how nature behaves.

[Mr Skeptic]

http://www.newscientist.com/channel/fundamentals/mg19626281.400-quantum-untanglement-is-spookiness-under-threat.html

 

doesn't help much, though

[Farsight]

Will further advances in the understanding of quantum mechanics overtake classical views of the physical world at all levels eventually? Why or why not?

 

No. Classical will overtake quantum mechanics. Here's an example of what I mean, an article from last week's New Scientist.

 

Quantum Entanglement: Is spookiness under threat?

 

In a nutshell it says Quantum Physics perhaps isn't so spooky after all, and the answer lies in geometry. I share that view. The link is just a stub I'm afraid, but the full article is worth reading.

[D H]

No. Quantum mechanics will not overtake classical views at all levels. Farsight is just plain goofy again. There is no reason to use quantum mechanics to describe a block sliding down a board and many reasons (over 10²³ reasons) not to. The same applies to relativity. There is no reason to use relativistic velocity addition equations for speeds much, much smaller than the speed of light.

 

Appropriate simplifications are an important part of physics. We even make simplifications within classical physics. For example, for small changes in elevation above the surface of the Earth one can assume a constant gravitational force, making the gravitational potential [math]E=mgh[/math] rather than [math]E=GmM_e/r-GmM_e/(r+h)[/math].

[Farsight]

...Farsight is just plain goofy again...

 

Read the article. Or be an shining example: don't read the article, just insult somebody who offers information that doesn't fit your preconceptions.

[swansont]

No. Classical will overtake quantum mechanics. Here's an example of what I mean, an article from last week's New Scientist.

 

Quantum Entanglement: Is spookiness under threat?

 

In a nutshell it says Quantum Physics perhaps isn't so spooky after all, and the answer lies in geometry. I share that view. The link is just a stub I'm afraid, but the full article is worth reading.

 

No, I don't think that's the nutshell.

 

The only mention of geometry is loop quantum gravity, and this is but one example of many flavors of "physics beyond QM" that are mentioned. One should note that there is nothing mentioned that has any concrete results yet. The paper by the main protagonist is still in review at PRL.

 

edit: several posts related to this topic copied from another thread

[Cap'n Refsmmat]

Joy Christian's paper on the subject is available on arXiv.

[fredrik]

Just to add a personal opinon as requested in th OP.

 

"Lee Smolin of the perimeter institute in Waterloo, Canada, for one, doubts that physicists can really make headway building a true theory of quantum gravity and spacetime before making some serious revisions to quantum theory itself. The inability of theorists to extend quantum theory to the entire universe, he suggests, may imply that it only works for parts of the universe, as an approximation of some deeper reality." (My italics.)

 

I think quantum theory needs to be revised. But, OTOH, what is the difference between revised and extended? It's a matter of point of view I guess.

 

In a certain sense QM is very beautiful, but there are some major problems I have with it, and that roots in the probability formalism used. When so anal about everything beeing measurable (which is GOOD), the foundations are seemingly an exception from this principle. The concept of objective probabilities are very foggy business IMO. Also the concept of objective probability spaces are similarly vague IMHO.

 

There is probably a still a very good explanation why the current models are still successful, and the extension will not change this, just like we can see why classical mechanics is still right for all practical purposes in most everyday scenarios.

 

I think QM is emergent, and the same goes for many of the symmetries.

 

One of the annoying things is the sometimes the theories are forumlate as if they were independent of an observer, while they can never be fundamentally so as far as I understand, only in en effective or emergent sense. For practical purposes, there is not always a difference, but the difference will be in the effectiveness in extended knowledge.

 

None of these ideas contradict current effective models though.

 

/Fredrik

[foodchain]

What if by simple chance the mathematical framework such as probability simply is describing what is going on at such a scale? I mean don’t get me wrong but simply put you don’t see a massive scale of questions launched on the most simple aspects of classical physics, why is it so different with QM? Its still just math used to describe and predict natural phenomena.

 

Here is my last question to it all. How do we gauge as Dawkins pointed out the impact of human processes on such a scale of trying to define the universe for lack of better words? I mean to apply the concept of a false vacuum, entropy and an energy well to people playing tennis I do not know if is common practice in physics. The question then comes to me is such simply a product of never using such understanding in such an endeavor.

 

If classical physics is as complex as it is currently and took as long as it did to reach its status, why would attempting to match something as complex as QM which has empirical proof to reality be any less simpler. Maybe its just that much more complex.

[fredrik]

What if by simple chance the mathematical framework such as probability simply is describing what is going on at such a scale?

 

I guess this comment was general, and perhaps not relating to my post but I'll just note to avoid beeing misunderstood. I personally don't have anything against uncertainty concepts and indeterminsm and leaving the classical realm, this is good stuff.

 

On the contrary, do i have serious objections on the determinism of probability in QM. The original idea of QM, is that while we can not in general determine the outcome of a particular experiment, we CAN determined exactly the probability - this is where it smells. This usually resorts to ridicilous reasoning of infinite experiment series and infinite data storage. The argumentation holds perfect in the practical sense, but it is not rigorous reasoning to me, but that's possibly relative.

 

The foundations on QM are IMO idealisations. Their support is the the implications of them are proven effective in experiments, which means they are GOOD idealisations. But if we now want to extend our understandin to the next step, the question is if these idealisations should be updated or if we want can patch on onto the existing ones. I see this as philosophical questions of science and it's method.

 

I mean don’t get me wrong but simply put you don’t see a massive scale of questions launched on the most simple aspects of classical physics, why is it so different with QM? Its still just math used to describe and predict natural phenomena.

 

I can't comment on the days where QM weren't known the mankind as I wasn't around but I figure that popping the realism of classical mechanics was an eye opener (it was for me). In the light of today, of course the fundaments of classical mechanics is even worse than than of QM. But that doesn't stop it from beeing excellent in most cases.

 

Here is my last question to it all. How do we gauge as Dawkins pointed out the impact of human processes on such a scale of trying to define the universe for lack of better words?

 

I am not familiar with his thinking, but what the impact of the self, on it's conception of the world view is I think necessarily massive, because I think my conception of the world lives within me (encoded the microstructure that makes me), where else would it reside? But what is me? Is my notes and books and computer part of me? How about society? I think there are different ways to the define a self but I can not think of the self as be defined unambigously without reference to it's environment and an organism is consistent only in it's right environment.

 

/Fredrik

[gcol]

Fredrik:

But if we now want to extend our understandin to the next step, the question is if these idealisations should be updated or if we want can patch on onto the existing ones. I see this as philosophical questions of science and it's method.

.

 

Nicely said, in my opinion.

 

Thanks one and all for your replies. I am getting an even clearer impression of who, among forum regulars, are stalwart defenders of the standard model, who are occasionally sniping at it, and who are mounting a frontal assault.

 

Any comments on the suggested limitations of Bell's hypothesis because of its reliance on "ordinary" numbers?

[fredrik]

This may seem like a lame answer but I personally haven't spent that much time analysing bell's theorem to pieces mainly because from my point of view, it's not a high relevance problem. It seems originally the motivation behind it was the desire to maintain the old ideals. I have persoanlly released those ideals on other grounds, and thus trying to find flaws in alternative grounds to release them can not be motivated for me.

 

But if there was motivation I think alot could be said about that, and the implicit ideas used in it.

 

For example locality itself, refers to the concept of space and distance. But what is space in the first place? If I'm not mistaken Ariel Caticha (who's proclaimed vision is to derive general relativity (classical) from some principles of inductive inference and Maximum entropy principles) has elaborated that space is rather defined in terms of relative influence. That distance is rather defined as a measure of influence or distinguishability. But how does one effectively separate 3D space from other generic configuration spaces? In particular if you spell out the locality assumption properly in terms of conditional probabilities and use bayes theorem, I can't help wonder why locality should be obvious.

 

There are many other things I prefer to get headache of than to try to restore local realism. Thereof my slightly misirected attention

 

/Fredrik

[swansont]

I'm also not a follower of the details of these experiments, but I wonder if it's been investigated to see if entangled particles are in a superposition and merely oscillating between the two states. This is such a fundamental issue that I can't imagine that it hasn't been investigated and disproven, but I've never checked to be sure.

[Farsight]

No, I don't think that's the nutshell. The only mention of geometry is loop quantum gravity, and this is but one example of many flavors of "physics beyond QM" that are mentioned. One should note that there is nothing mentioned that has any concrete results yet. The paper by the main protagonist is still in review at PRL.

 

See the bottom of page 38:

Smolin and Fotini Markopoilou, also at the Perimeter Institute, have been exploring how hints of that deeper theory might emerge from primitive notions of geometry.

Yes, the article then moves on to Loop Quantum Gravity, but search the internet on "Loop Quantum Geometry" or look for recent papers from Lee Smolin. There was one on about the 7th October that caught my eye, but I can't find it now and must dash:

 

http://www.google.co.uk/search?hl=en&q=%22loop+quantum+geometry%22

 

http://arxiv.org/find/grp_physics/1/au:+smolin/0/1/0/all/0/1

[swansont]

See the bottom of page 38: Yes, the article then moves on to Loop Quantum Gravity, but search the internet on "Loop Quantum Geometry" or look for recent papers from Lee Smolin. There was one on about the 7th October that caught my eye, but I can't find it now and must dash:

 

Yes, the article mentions Smolin and LQG as a geometry argument — once. It's not the article "in a nutshell." Other people and approaches are mentioned as well, and the main point of the article was work by Christian.

[Farsight]

Look at the picture on page 39. That's Christian's non-commutative operation. And what sort of operation is it? Why, it's a rotation. A geometrical operation.

 

If you'd rather believe in spooky action at a distance than openly acknowledge what's actually in the article, or search Joy Christian's paper for geometric, maybe it's time we had a new physics "expert" round here.

[foodchain]

Look at the picture on page 39. That's Christian's non-commutative operation. And what sort of operation is it? Why, it's a rotation. A geometrical operation.

 

If you'd rather believe in spooky action at a distance than openly acknowledge what's actually in the article, or search Joy Christian's paper for geometric, maybe it's time we had a new physics "expert" round here.

 

Well the Schrödinger equation still stands I think, so does the time evolution operator so maybe we should just wait until something occurs because that’s how it works. If quantum mechanics does not work, or simply put if at the smallest scale you had no stability then relatively speaking I would think the universe to be a bit drastic in regards to difference.

 

Look, I am a QM fanboy. I wish people would redo classical from a quantum perspective, or find a way to let it out of the atom into the universe, such is not occurring as rapidly as I would hope. Geometry, well that’s invented by humans, the best bet is not trying to get in an idealist camp and maybe trying to figure out how nature works. If you like Einstein and relativity so much you should accept QM on the basis that he predicted BEC from such and it was validated and is now a baby field of physics with much promise for further understanding, he also said science was the most important thing we have and its primitive and childlike. Those are not his exact words but very similar. Relativity like QM has problems, this is not something hidden. I don’t very much care about this either to be honest because I rely more or less on the empirical, not some new formation of math. QM and relativity both have empirical support, so the big problem I think is getting them to work together. Sadly I don’t think that will occur in the midst of ape warfare.

[swansont]

Look at the picture on page 39. That's Christian's non-commutative operation. And what sort of operation is it? Why, it's a rotation. A geometrical operation.

 

Rotations were offered as an example of a non-commuting operation. How do I conclude this?

 

"Take rotations in space,

for example. They differ fundamentally from

ordinary numbers in one important respect:

the order of rotations matters (see Diagram).

Rotations do not commute."

 

But there are lots of operations that don't commute, so you can't conclude that Christian's work is based on rotations based on the article.

 

If you'd rather believe in spooky action at a distance than openly acknowledge what's actually in the article, or search Joy Christian's paper for geometric, maybe it's time we had a new physics "expert" round here.

 

I was commenting on the Quantum Untanglement article only, so searching Christian's paper is moot. "geometry" showed up exactly once in my search.

 

"Smolin and Fotini Markopoulou, also at the

Perimeter Institute, have been exploring how

hints of that deeper theory might emerge from

primitive notions of geometry. Their research

centres on the concept of loop quantum

gravity ..."

 

If Christian's work is centered on geometry, blame Mark Buchanan for writing a crappy summary, because he doesn't mention it.

[Farsight]

Foodchain: I think Relativity is imperfect, but I don't reject it. In similar vein I don't reject QM. The mathematics works. But we don't understand what it means. The issue with Quantum Mechanics has always been the interpretation of what's actual going on in the subatomic world. I don't reject QM, instead what I reject is the idea that we can never understand what it's telling us, and I reject the weird unprovable stuff like parallel worlds. I'm now adopting the view that the underlying issues are associated with the concept of point particles, and a better interpretation is available by considering "particles" to be extended non-local volumetric entities, saying, in effect: "the wave function is the particle". It means (despite the photoelectric effect and Einstein's Nobel Prize) that the photon really is a wave, and then geometry becomes utterly crucial. I really do think this is the route to combining QM and Relativity. In a way this is "my area", and I'm much more sensitive to it than others. I know what these guys are on about. So whilst people might claim I see what I want to see, in the article, I see Gerard t'Hooft, I see Smolin talking geometry again, I see the picture of the geometrical rotations. And I see four instances of "geometric" in Joy Christian's paper, where I also see this:

 

 

...It is crucial to note that the ej appearing in the above definition are not the usual self-adjoint operators on a complex Hilbert space' date=' but are the ordinary 3-vectors in the real physical vector space...

 

...appearing therein is not the unit imaginary i = √−1, but a real geometric entity...

 

...a volume form...

 

...a classical relation...

 

...a local realistic model can be constructed to exactly reproduce quantum mechanical correlations...

 

...spacelike separated...

 

...sharper geometrical meaning...

 

...classical, local realistic framework...

 

...orthogonal directions in the physical space...

 

...algebraic properties of the physical space...[/quote']

[Mr Skeptic]

I too think the best solution to the wave particle duality is to say, "Well duh! It's a wave-particle (quantized wave?) just like everything else."

[Farsight]

Or you could think along the lines of Chinatown:

 

Evelyn Mulwray: She's my daughter.

[Gittes slaps Evelyn]

Jake Gittes: I said I want the truth!

Evelyn Mulwray: She's my sister...

[slap]

Evelyn Mulwray: She's my daughter...

[slap]

Evelyn Mulwray: My sister, my daughter.

[More slaps]

Jake Gittes: I said I want the truth!

Evelyn Mulwray: She's my sister AND my daughter!

 

*******************************************

 

Foodchain: I think Relativity is imperfect, but I don't reject it. In similar vein I don't reject QM. The mathematics works. But we don't understand what it means. The issue with Quantum Mechanics has always been the interpretation of what's actual going on in the subatomic world. I don't reject QM, instead what I reject is the idea that we can never understand what it's telling us, and I reject the weird unprovable stuff like parallel worlds. I'm now adopting the view that the underlying issues are associated with the concept of point particles, and a better interpretation is available by considering "particles" to be extended non-local volumetric entities, saying, in effect: "the wave function is the particle". It means (despite the photoelectric effect and Einstein's Nobel Prize) that the photon really is a wave, and then geometry becomes utterly crucial. I really do think this is the route to combining QM and Relativity. In a way this is "my area", and I'm much more sensitive to it than others. I know what these guys are on about. So whilst people might claim I see what I want to see, in the article, I see Gerard t'Hooft, I see Smolin talking geometry again, I see the picture of the geometrical rotations. And I see four instances of "geometric" in Joy Christian's paper, where I also see this:

 

Well? Come on fellas. Cat got your tongue? Am I the only one who actually reads articles and scientific papers? Or writes them? Or would you rather run off and hide than apologise for your sneering abuse and admit that I've got a point?

[swansont]

Well? Come on fellas. Cat got your tongue? Am I the only one who actually reads articles and scientific papers? Or writes them? Or would you rather run off and hide than apologise for your sneering abuse and admit that I've got a point?

 

I guess you need to define what you mean by a "geometrical argument" because I assumed it was similar to e.g. relativity, in that space in non-Euclidean. Discussing the various operations within Euclidean space means that everything is a geometric argument, in which case "it's a geometrical argument" has no meaning.

 

Until you have a paper published in a peer-reviewed journal, you can't validly claim to write them.

[Brian H]

The probability wave idea is problematic to me, in that I want to know where and how the probability is stored and recorded, and how it persists and is "objectified". Perhaps there is some level of description beyond which infinite regression or self-reference is unavoidable. That would then have to qualify as the Final Theory, I suppose.

[fredrik]

The probability wave idea is problematic to me, in that I want to know where and how the probability is stored and recorded, and how it persists and is "objectified".

 

I personally think this is a sound objection. I think when we can answer this in it's full, we may also understand how the probability spaces as well as classical structures are formed and how it relates to fundamental concepts like mass.

 

In my preferred view, the observer is the realisation of the record, and subjective probabilities are induced from the observer himself. Any objective, as opposed to subjective probabilities would only make sense to the extent there is anagreement between a large set of observers. The emergent physical nature of the observer, is the microstructure who is used to encode and store information. In this view it's clear that complex microstructures will have a larger "intertia" against change, than does a simpler structure. There seems to be some close connection between intertia (as in resistance against perturbation) and the "record capacity".

 

What remains is to identify a successful formalism to implement this, and how to pull out of it also time and space. To understand exactly how all structures emerges out of the basic principles. And in this context most probably background structures like space and superimposed structures like particles must be unified.

 

In expect that this almost philosophical questions will get an answer eventually.

 

/Fredrik