Spacetime Geometry may "falsify" locality?

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sciborg2

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« on: September 21, 2013, 02:36:41 pm »
A Jewel at the Heart of Quantum Physics

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The new geometric version of quantum field theory could also facilitate the search for a theory of quantum gravity that would seamlessly connect the large- and small-scale pictures of the universe. Attempts thus far to incorporate gravity into the laws of physics at the quantum scale have run up against nonsensical infinities and deep paradoxes. The amplituhedron, or a similar geometric object, could help by removing two deeply rooted principles of physics: locality and unitarity.

“Both are hard-wired in the usual way we think about things,” said Nima Arkani-Hamed, a professor of physics at the Institute for Advanced Study in Princeton, N.J., and the lead author of the new work, which he is presenting in talks and in a forthcoming paper. “Both are suspect.”

Locality is the notion that particles can interact only from adjoining positions in space and time. And unitarity holds that the probabilities of all possible outcomes of a quantum mechanical interaction must add up to one. The concepts are the central pillars of quantum field theory in its original form, but in certain situations involving gravity, both break down, suggesting neither is a fundamental aspect of nature.

For some context:

Physicists Discover Geometry Underlying Particle Physics


Kellais

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« Reply #1 on: September 22, 2013, 12:22:47 pm »
This is why i love Physics and Math  8)

Fascinating.

Although as someone who is not that versed in physics, i'm not sure if understand this properly  ;D
As a mathematician, i am more than baffled at the idea that somehow there is a "space" where probabilities can sum up to a value greater than 1...it's just ... wrong  :o How can something add up to more than "absolut certainty"?!
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Meyna

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« Reply #2 on: September 22, 2013, 10:04:57 pm »
This is why i love Physics and Math  8)

Fascinating.

Although as someone who is not that versed in physics, i'm not sure if understand this properly  ;D
As a mathematician, i am more than baffled at the idea that somehow there is a "space" where probabilities can sum up to a value greater than 1...it's just ... wrong  :o How can something add up to more than "absolut certainty"?!

From what I can gather (reading comments on various websites discussing this), this model doesn't propose probabilities for quantum systems adding up to something other than 100%, but, rather, that instead of assuming unitarity (probabilities adding up to 100%) for quantum systems a priori, this model results in unitarity as a consequence.

For reference, I was looking through comments on this article: https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics/

posted on Reddit: http://www.reddit.com/submit?url=https%3A%2F%2Fwww.simonsfoundation.org%2Fquanta%2F20130917-a-jewel-at-the-heart-of-quantum-physics%2F
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Kellais

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« Reply #3 on: September 22, 2013, 10:39:01 pm »
Heh, serves me right for assuming things  :-X But i have the excuse of not enough sleep in the last couple of days  ;D Now it makes more sense.
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Meyna

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« Reply #4 on: September 23, 2013, 02:45:56 am »
Heh, serves me right for assuming things  :-X But i have the excuse of not enough sleep in the last couple of days  ;D Now it makes more sense.

A lot of readers definitely took the same message away from these articles, so I don't think it's too big a misstep on your part. Heck, I have a degree in physics and I needed some other opinions before I started to understand what was being asserted here.
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Kellais

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« Reply #5 on: September 23, 2013, 10:11:17 am »
Ok, this is at least less embarrasing now  ;)

I am a mathematician though and just should not have jumped to conclusions...that's unprofessional  ;D

Anyway...i clicked on your first url and hot damn...some quotes:

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Interactions that were previously calculated with mathematical formulas thousands of terms long can now be described by computing the volume of the corresponding jewel-like “amplituhedron,” which yields an equivalent one-term expression.

Wow...that's indeed mind-boggling. And super elegant. Some theories are just flat out better than others  ;)

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In keeping with this idea, the new geometric approach to particle interactions removes locality and unitarity from its starting assumptions. The amplituhedron is not built out of space-time and probabilities; these properties merely arise as consequences of the jewel’s geometry.

The important part, i guess. And i have bolded what you so neatly summarized in your second last post.
Again, very elegant if the theory holds.
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Meyna

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« Reply #6 on: September 23, 2013, 12:22:34 pm »
Indeed; even though this is just a different perspective of concepts we already take for granted, it does simplify things (a lot!), which makes it a promising lead in our hunt for a quantum theory that plays nice with general relativity.
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« Reply #7 on: September 23, 2013, 05:40:31 pm »
I really enjoy these ideas of movement and geometry - for instance, the shapes generated by the elliptical orbit of the celestial spheres. And Cymatics 8).

But I'd need some serious maths learning before I could appreciate or contribute to conversations such as these.
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