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(Wired)   Today's word of the day: amplituhedron   ( wired.com) divider line
    More: Cool, quantum systems, gluons, learning, quantum field theory, virtual particles, quantum gravity, higher dimensions, Richard Feynman  
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8535 clicks; posted to Main » on 12 Dec 2013 at 1:50 PM (3 years ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-12-12 02:14:02 PM  
3 votes:
So, on Dec 6 Arkani-Hamed and Trnka publish in the Arxiv their awaited paper "The Amplituhedron".

Perturbative scattering amplitudes in gauge theories have remarkable simplicity and hidden infinite dimensional symmetries that are completely obscured in the conventional formulation of field theory using Feynman diagrams. This suggests the existence of a new understanding for scattering amplitudes where locality and unitarity do not play a central role but are derived consequences from a different starting point. In this note we provide such an understanding for N=4 SYM scattering amplitudes in the planar limit, which we identify as ``the volume" of a new mathematical object--the Amplituhedron--generalizing the positive Grassmannian. Locality and unitarity emerge hand-in-hand from positive geometry.

Does Wired get some expert(s) to discuss what is revealed in this paper that was just alluded to before? Nope. They just reprint an analysis from September 17, 2013 (that already appeared in Fark).

One of the greatest achievements in modern maths/physics was Emmy Noether's proof that any symmetry corresponds to a conserved quantity.
2013-12-12 02:37:54 PM  
2 votes:
I thought there was someone who had a geometrical solution to the particle model long ago.  It doesn't mean this is a bad thing; I'd rather see a good idea rehashed every six months.  Like the Eightfold Path, the Standard Model has models slapped on to it, but nobody knows why.  Experimental physicists care about 'how' before 'why', and I never did like the concept of 'renormalizing infinities'.  "Oh, the math says this integral goes to infinity.  But we know the probability can't be more than 100% so we'll just spackle over the holes in the mathematics."
2013-12-12 02:17:38 PM  
2 votes:

Marcus Aurelius: nmrsnr: I'm cautiously optimistic that this thing will actually lead to new ways of thinking about/understanding/teaching particle physics, similar to how Feynman diagrams simplified and made abstract concepts more concrete.

Theoretical physicists are more conservative and resistant to change than any known force in the universe.


I was going to ask how you came to that conclusion, but I decided it didn't matter.
2013-12-12 01:26:29 PM  
2 votes:
I'm cautiously optimistic that this thing will actually lead to new ways of thinking about/understanding/teaching particle physics, similar to how Feynman diagrams simplified and made abstract concepts more concrete.
2013-12-12 04:35:30 PM  
1 vote:
So...... is this a breakthrough that I should wish I was fully able to understand or should it be dismissed as witchcraft of some kind?
2013-12-12 04:24:32 PM  
1 vote:
So then...this guy had it right?

www.timecube.com
2013-12-12 04:16:40 PM  
1 vote:
Aliens:  Wow!  Look at you guys.  You've really come a long way.  How did you do it?

Us: Well, we derived a mathematical model of the universe.

Aliens:  Oh.  Math.  We tried that.  Turns out it's ultimately a dead end.
2013-12-12 03:57:05 PM  
1 vote:
I'm really hoping that I'm alive when we solve physics. That, or we create a true human-level AI, or we make contact with an extraterrestrial intelligence. Seriously, can we do one of those within the next, oh, forty years? That would be awesome.
2013-12-12 03:52:16 PM  
1 vote:

chumboobler: I am still in the anti "time" camp. I think it should be decay of solvency. Time is a fictional thing that man made up to track things.  Time exists, but not as time as we know it.  It is all about decay of bonds in molecules and those vary wildly depending on the molecule involved...... If we give up time as an absolute, we will progress. It varies greatly depending on what and where you are.


When the Sun shines upon Earth, 2 - major Time points are created on opposite sides of Earth - known as Midday and Midnight. Where the 2 major Time forces join, synergy creates 2 new minor Time points we recognize as Sunup and Sundown.
2013-12-12 03:47:59 PM  
1 vote:
here is a video on the subject:

The Amplituhedron
Nima Arkani-Hamed

http://susy2013.ictp.it/video/05_Friday/2013_08_30_Arkani-Hamed_4-3. ht ml
2013-12-12 03:21:31 PM  
1 vote:
Turtles. Turtles all the way down.
2013-12-12 03:06:04 PM  
1 vote:

syrynxx: I thought there was someone who had a geometrical solution to the particle model long ago.  It doesn't mean this is a bad thing; I'd rather see a good idea rehashed every six months.  Like the Eightfold Path, the Standard Model has models slapped on to it, but nobody knows why.  Experimental physicists care about 'how' before 'why', and I never did like the concept of 'renormalizing infinities'.  "Oh, the math says this integral goes to infinity.  But we know the probability can't be more than 100% so we'll just spackle over the holes in the mathematics."


Renormalization is less weird when viewed from a modern context (see Anthony Zee's text for a good intro).  Basically, introducing a cutoff into the theory isn't some ad-hoc procedure merely to remove infinities.  It's an acknowledgment that the theory will break down at high energies.  But then you remove the cutoff to recover precisely the physics that doesn't depend on high-energy details, i.e. the part that's useful in practice, in the absence of a better theory.  From this perspective, renormalization is actually expected, not a kludge, and it points the way to theories (precisely the renormalizable ones) that are useful approximations.
2013-12-12 02:06:48 PM  
1 vote:
Very cool. Thanks, subby.
2013-12-12 02:06:02 PM  
1 vote:

DerAppie: Didn't we already have a thread or two about this?


This is a new facet
2013-12-12 02:05:12 PM  
1 vote:
Didn't we already have a thread or two about this?
 
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