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A Jewel at the Heart of Quantum Physics

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Re: A Jewel at the Heart of Quantum Physics

#61

Post by VLM »

has2k1 wrote: post #33
noonespecial wrote: post #5

Every once in a while I get the feeling that the greatest discoveries are still ahead and these next few decades might be the real "golden age of science". The "individual genius" phase is just behind us and the "collaborative brilliance" phase is just beginning.

It is possible that Gravity as we know it is an illusion. For example, the Newtonian take on Gravity was that it was a force. That according to Einstein was illusory, Gravity was really a geometric manifestation due to the curvature of space-time. With that take Gravity as we know it is different from the Gravity as was once known. However the Newtonian view that Gravity is a force can and still does facilitate usefu…

Perhaps another analogy for an illusion of a force would be centrifugal force?

Re: A Jewel at the Heart of Quantum Physics

#62

Post by bsullivan01 »

redhat-reallyp wrote: post #55
bsullivan01 wrote: post #35

Earlier quoted context omitted.

what are your qualifications? No offense meant, but I am trying to see if this is real or not. Quite a few smart people seem excited by it, yet you dismiss it

"Quite a few smart people seem excited by it" Why aren't you asking them for their qualifications, then? Serious question, think about what your choice implies. Is it that "you want to believe", perhaps? You don't need a PhD in quantum physics to detect the hype in this article. The comment I responded to was reacting more to the unsupported claims and hype than any actual discovery. "yet you dismiss it" I'm not dism…

Why aren't you asking them for their qualifications, then?

Don't need to, checked them as they posted their names and all their research is online. http://arxiv.org/abs/1212.5605

They also posted the math behind it (which went over my head) unlike you. Next time, if you want to be taken seriously explain yourself better and try to be specific. If you know what you are talking about, of course.

Re: A Jewel at the Heart of Quantum Physics

#63

Post by mrcactu5 »

Nima Arkani-Hamed is a nortorious loudmouth.

I went to his lecture from 1-3 and we got an encore from 3-5 and another from 5-6. It is no surprise his paper is verbose clocking at 154 pages.

Scattering Amplitudes and the Positive Grassmannian http://arxiv.org/abs/1212.5605

Alejandro Morales has some lecture notes on a course on the Positive Grassmanian The professor was Alexander Postnikov at MIT.

http://www.thales.math.uqam.ca/~ahmorales/18.318lecs/lecture...

Feynman famously said "I think I can safely say that nobody understands quantum mechanics." That was in 1965 but it's still true.

The scattering amplitudes in a certain case of N=4 Super Yang-Mills theory are more symmetric than people first expected. This has applications to "total positivity" and "integrable systems".

This will not help you build an app, but it's beautiful and represents an important shift in mathematics.

Re: A Jewel at the Heart of Quantum Physics

#64

Post by selimthegrim »

biot wrote: post #42
selimthegrim wrote: post #17

Earlier quoted context omitted.

I was talking to a friend in the physics department at Stanford a few months ago about how one of the people whose work is cited in this paper (Greg Moore of Rutgers) had found analytic expressions purely rooted in geometry for Bethe Ansatz[1] results in (1+1) dimensional systems. Based on that, I told my friend I believed these "physical mathematics types" (as they call themselves) were on to something. He concurred…

In other words, you made a comment four months ago that simple, geometric models are likely to be important?

The point was that these techniques that people are decrying as just applying to super idealized cases in N=4 SUSY produced real computationally and experimentally testable results in real lower dimensional systems. However, no one is going to be putting out excited press releases about thermodynamic Bethe Ansaetze.

Re: A Jewel at the Heart of Quantum Physics

#65

Post by jessriedel »

gaze wrote: post #7
gruseom wrote: post #2

Is anyone here familiar with this work? I would like to hear more about it. At a minimum, this article is very much better than the usual science blog filler—it contains signs of a genuine conceptual breakthrough. For example: “You can easily do, on paper, computations that were infeasible even with a computer before.” That doesn't happen very often! Or this: [T]he new geometric approach to particle interactions remo…

This isn't my field (a.k.a. I'm talking out of my ass), but I can give it my best shot. Usually with QFT you start with locality and unitarity as a sort of starting point. You might hope that you could come up with something much simpler where locality and unitarity come about naturally from the model itself (the goal of physics being to show that "it had to be this way".) QFT tells us how the world works by calculat…

Do you know of a good review paper?

Re: A Jewel at the Heart of Quantum Physics

#66

Post by loup-vaillant »

slacka wrote: post #53
ssivark wrote: post #22

Earlier quoted context omitted.

I've been keenly following this area of research and have heard some of the talks and read some papers. I concur with the sketch given by @gaze. 1. The notion of unitarity is a "common sense" rule that implies that you can consistently assign probabilities to possible outcomes in a quantum mechanical experiment ( http://en.wikipedia.org/wiki/Unitarity_%28physics%29 ) 2. The notion of locality states that what happens…

> 2. The notion of locality states that what happens on Jupiter better not affect how fast your code compiles this morning (or how experiments run on earth). This is an important postulate, because if this weren't true, we might as well give up on doing science as there would be arbitrarily many external influences we couldn't take into account. Unfortunately for science, the principle of locality has been violated m…

I bet my arm that in a Many World Interpretation of Quantum mechanics, those apparent non-localities have not, in fact, have been violated.

We can have a classical analogy to this. Put a blue ball and a red ball in a black box. Shake the box. Without looking, take a ball from the box and put it in a black safe. That way, you should have no idea which ball in in the safe.

Now send the black box to your colleagues on Mars, along with a copy of your experimental protocol. Let them open the box. And, lo and behold, the instant they see the ball, they know which colour your ball is, despite the fact you're separated by several light-minutes. As if information travelled faster than light —no, scrap that, instantaneously.

Quite underwhelming, isn't it? Well, the EPR though (and actual) experiments work on similar principles: there is a common cause. When 2 particles are entangled, it means they share information. When you send those particles away in opposite directions, they carry this information with them, at Slower Than Light speed. Then we perform some experiment on one of the two particles, and we know instantly how some other experiment is likely to turn out with the other particle.

It's that mundane. It only gets confusing when you talk of "probabilities", instead of talking of the square of complex amplitudes… which are a bit different from actual probabilities. In the Copenhagen interpretation of quantum mechanics, we tend to think of the universe as unique, and the laws of physics have some fundamental randomness in them. The Many World interpretation is simpler: no randomness, just a universe that splits in multiple blobs that eventually cease to interact with each other (The split is not instantaneous: it propagates at the speed of light at most).

So, when you perform that experiment with the first particle, you're not telling the second one how to behave. You merely learn which universe you are living in.

---

Now, find a reliably replicated experiment where information was transmitted faster than light, and I will be choking through sheer astonishment.

Re: A Jewel at the Heart of Quantum Physics

#67

Post by redhat-reallyp »

vinceguidry wrote: post #60
redhat-reallyp wrote: post #55

Earlier quoted context omitted.

"Quite a few smart people seem excited by it" Why aren't you asking them for their qualifications, then? Serious question, think about what your choice implies. Is it that "you want to believe", perhaps? You don't need a PhD in quantum physics to detect the hype in this article. The comment I responded to was reacting more to the unsupported claims and hype than any actual discovery. "yet you dismiss it" I'm not dism…

In other words you just spent a dozen or so paragraphs venting your bullshit detector in a space where numerous contributors that are much, much smarter than you have indicated otherwise. It's like inverse bike shedding.

Perhaps you missed the part of my very short comment where I wrote "I'm not dismissing that the work could have value, but the article makes claims that go far beyond anything that's been demonstrated."

You might want to re-read my original comment and take note of the issues I commented on. If you disagree with what I'm saying, why not respond on those points? I can't help wonder if your problem is actually that I'm interfering with your "I want to believe" circuitry.

I like to distinguish between actual science and mathematics and nonsensical metaphysical claims like "...giving up space and time as fundamental constituents of nature and figuring out how the Big Bang and cosmological evolution of the universe arose out of pure geometry." YMMV.

Re: A Jewel at the Heart of Quantum Physics

#68

Post by redhat-reallyp »

bsullivan01 wrote: post #62
redhat-reallyp wrote: post #55

Earlier quoted context omitted.

"Quite a few smart people seem excited by it" Why aren't you asking them for their qualifications, then? Serious question, think about what your choice implies. Is it that "you want to believe", perhaps? You don't need a PhD in quantum physics to detect the hype in this article. The comment I responded to was reacting more to the unsupported claims and hype than any actual discovery. "yet you dismiss it" I'm not dism…

Why aren't you asking them for their qualifications, then? Don't need to, checked them as they posted their names and all their research is online. http://arxiv.org/abs/1212.5605 They also posted the math behind it (which went over my head) unlike you. Next time, if you want to be taken seriously explain yourself better and try to be specific. If you know what you are talking about, of course.

You're comparing me to the authors of the work? My misunderstanding then, I thought you were comparing my take to that of other commenters.

"try to be specific"

I did post specifics, include a link to an example of the issues with supersymmetry as a physical model.

"explain yourself better"

If you can identify what you didn't understand, I'd be happy to explain it further. I stand by my comment - it doesn't contain anything non-factual that can't be supported with references, although when it comes to silly metaphysical claims about the universe arising from pure geometry, those references are going to be to philosophy texts, not science texts. Which hints at the problem with the claim in the first place.

Re: A Jewel at the Heart of Quantum Physics

#69

Post by polaris9000 »

It is discoveries like this one that always makes me wish I had pursued physics or mathematics back in college. There are so many things in Nature yet to be discovered! Imagine all of the mysteries that await us in the future. Take, for example, the theoretical graviton particle. What will happen once it is finally "discovered"?

Thanks for the article; It is articles like this that make me want to go back to school and major in physics or mathematics.

Re: A Jewel at the Heart of Quantum Physics

#70

Post by loup-vaillant »

redhat-reallyp wrote: post #13
gruseom wrote: post #2

Is anyone here familiar with this work? I would like to hear more about it. At a minimum, this article is very much better than the usual science blog filler—it contains signs of a genuine conceptual breakthrough. For example: “You can easily do, on paper, computations that were infeasible even with a computer before.” That doesn't happen very often! Or this: [T]he new geometric approach to particle interactions remo…

"it contains signs of a genuine conceptual breakthrough." It contains claims of such signs, which seems to be the point of this fluff piece. Alarm bells should go off when you read statements like this: "...giving up space and time as fundamental constituents of nature and figuring out how the Big Bang and cosmological evolution of the universe arose out of pure geometry." Ah yes, well that solves the mystery, doesn'…

> Ah yes, well that solves the mystery, doesn't it. The universe arose out of pure geometry.

That was a serious hypothesis before this. Heard about Tegmark's level IV multiverse? It's the idea that every mathematical structure just "exists", like "poof magic", and the simpler ones would, like, have greater weight. Kind of a literal interpretation of Occam's Razor, really. A corrolary is, the simpler the laws of physics are, the more probable the above hypothesis is. And suddenly we learn that the true laws of physics might be much simpler than we anticipated? This is huge.

Or not.

The idea of a timeless universe, where our subjective notion of time just arise from its structure has been around for quite some… time.

Likewise, Occam's Razor itself suggests that the true laws of physics are simpler than we think. Plus, current human laws of physics are either false or incomplete. I fully expect future physics to be further simplified. Claims of massive simplification are therefore not that surprising.

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That said, I agree with your specific objections (the "work in progress" warnings).

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