Farewell Feynman Diagrams?

Study matter and its motion through spacetime...

Moderators: Calilasseia, ADParker

Re: Farewell Feynman Diagrams?

#21  Postby Steve » Sep 19, 2013 4:42 pm

I am not a mathematician, but does this have the potential to advance the language of physics sort of like calculus in Newtons day? That would be very cool. No hot. I said I wasn't a mathematician, right?
As your desire is, so is your will.
As your will is, so is your deed.
As your deed is, so is your destiny
Blue Mountain Center of Meditation
User avatar
Steve
RS Donator
 
Posts: 6908
Age: 64
Male

New Zealand (nz)
Print view this post

Ads by Google


Re: Farewell Feynman Diagrams?

#22  Postby Rumraket » Sep 19, 2013 8:39 pm

DavidMcC wrote:
Rumraket wrote:Oh my god, this is crystal power crap isn't it? :lol:

Not sure it is. Any resemblance to a real crystal is coincidental.
That doesn't make it correct, though, just not necessarily woo, any more than E8 was woo.

I was joking. :)
Half-Life 3 - I want to believe
User avatar
Rumraket
 
Posts: 13148
Age: 39

Print view this post

Re: Farewell Feynman Diagrams?

#23  Postby iamthereforeithink » Sep 19, 2013 8:44 pm

Yoohoo! I would advise the OP to change his username to "amplituhedron59". We don't need 'em twistors anymore.
“The supreme art of war is to subdue the enemy without fighting.” ― Sun Tzu, The Art of War
User avatar
iamthereforeithink
 
Posts: 3332
Age: 9
Male

Country: USA/ EU
European Union (eur)
Print view this post

Re: Farewell Feynman Diagrams?

#24  Postby Rumraket » Sep 19, 2013 8:46 pm

Steve wrote:I am not a mathematician, but does this have the potential to advance the language of physics sort of like calculus in Newtons day? That would be very cool. No hot. I said I wasn't a mathematician, right?

And relatedly, will this help with significantly reducing the computational cost of simulating fundamental physics by simplifying the mathematics required to model it?
Half-Life 3 - I want to believe
User avatar
Rumraket
 
Posts: 13148
Age: 39

Print view this post

Re: Farewell Feynman Diagrams?

#25  Postby newolder » Sep 19, 2013 9:46 pm

Rumraket wrote:
Steve wrote:I am not a mathematician, but does this have the potential to advance the language of physics sort of like calculus in Newtons day? That would be very cool. No hot. I said I wasn't a mathematician, right?

And relatedly, will this help with significantly reducing the computational cost of simulating fundamental physics by simplifying the mathematics required to model it?

sure... he's claimed to have done a calculation in-flight on 1/2 a sheet of paper. 100 dollar flight, 1 cent paper + pencil = much less than a 'personal assistant' asking wolfram-alpha. :cheers:
Geometric forgetting gives me loops. - Nima A-H
User avatar
newolder
 
Name: Albert Ross
Posts: 6531
Age: 8
Male

Country: Feudal Estate number 9
Print view this post

Re: Farewell Feynman Diagrams?

#26  Postby natselrox » Sep 20, 2013 5:45 am

Amplituhedron... Amplituhardon... Hard on Amplitude... Go home physics, you're drunk...
When in perplexity, read on.

"A system that values obedience over curiosity isn’t education and it definitely isn’t science"
User avatar
natselrox
 
Posts: 10037
Age: 107
Male

India (in)
Print view this post

Re: Farewell Feynman Diagrams?

#27  Postby twistor59 » Sep 20, 2013 6:22 am

:lol:
iamthereforeithink wrote:Yoohoo! I would advise the OP to change his username to "amplituhedron59". We don't need 'em twistors anymore.


Once a twistor always a twistor :dance:
A soul in tension that's learning to fly
Condition grounded but determined to try
Can't keep my eyes from the circling skies
Tongue-tied and twisted just an earthbound misfit, I
User avatar
twistor59
RS Donator
THREAD STARTER
 
Posts: 4966
Male

United Kingdom (uk)
Print view this post

Ads by Google


Re: Farewell Feynman Diagrams?

#28  Postby newolder » Sep 20, 2013 8:57 am

Much scope for etymological play-time. Amp = electric current, lit = aflame, u = not i, he = male, dron(e) = bee/ant/bug. Gives, "Don't put your daughter on the stage, Mrs Worthington." - Nope, natselrox is rite, hic. :drunk:
Geometric forgetting gives me loops. - Nima A-H
User avatar
newolder
 
Name: Albert Ross
Posts: 6531
Age: 8
Male

Country: Feudal Estate number 9
Print view this post

New Physics Geometry?

#29  Postby Sovereign » Sep 21, 2013 6:43 pm

Physicists have discovered a jewel-like geometric object that dramatically simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality.

“This is completely new and very much simpler than anything that has been done before,” said Andrew Hodges, a mathematical physicist at Oxford University who has been following the work.

The revelation that particle interactions, the most basic events in nature, may be consequences of geometry significantly advances a decades-long effort to reformulate quantum field theory, the body of laws describing elementary particles and their interactions. 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.

“The degree of efficiency is mind-boggling,” said Jacob Bourjaily, a theoretical physicist at Harvard University and one of the researchers who developed the new idea. “You can easily do, on paper, computations that were infeasible even with a computer before.” Continued...

https://www.simonsfoundation.org/quanta ... m-physics/
Sovereign
 
Posts: 2989
Male

United States (us)
Print view this post

Re: New Physics Geometry?

#30  Postby Thomas Eshuis » Sep 21, 2013 6:46 pm

Already a thread here.
"Respect for personal beliefs = "I am going to tell you all what I think of YOU, but don't dare retort and tell what you think of ME because...it's my personal belief". Hmm. A bully's charter and no mistake."
User avatar
Thomas Eshuis
 
Name: Thomas Eshuis
Posts: 30143
Age: 30
Male

Country: Netherlands
European Union (eur)
Print view this post

Re: New Physics Geometry?

#31  Postby Sovereign » Sep 21, 2013 6:51 pm

I missed that :oops:
Sovereign
 
Posts: 2989
Male

United States (us)
Print view this post

Re: Farewell Feynman Diagrams?

#32  Postby advaitya » Sep 22, 2013 8:22 am

I read the article. On the one hand, it gives the impression that the researchers have simply landed upon a more efficient method of doing certain calculations.

But the article also quotes the researchers speculating that space and time might not be fundamental features of the universe. Where would it leave gravity, which in GR is an effect of spacetime? Does gravity become something non-fundamental, or emergent as well?
advaitya
 
Posts: 323
Age: 37
Male

Country: India
India (in)
Print view this post

Re: Farewell Feynman Diagrams?

#33  Postby twistor59 » Sep 22, 2013 10:40 am

advaitya wrote:I read the article. On the one hand, it gives the impression that the researchers have simply landed upon a more efficient method of doing certain calculations.

But the article also quotes the researchers speculating that space and time might not be fundamental features of the universe. Where would it leave gravity, which in GR is an effect of spacetime? Does gravity become something non-fundamental, or emergent as well?


As I understand it, the new method simplifies the calculation of scattering amplitudes for <curly!>N=4 Supersymmetric Yang Mills theory. This is a gauge theory and it doesn't explicitly contain any gravity. However, in the AdS-CFT correspondence, this Yang Mills theory is thought of as living on the boundary of bulk spacetime. Spacetime, of course, contains gravity and AdS-CFT provides a dictionary for translating between the bulk theory with gravity and the boundary theory without gravity. So, in this sense, yes gravity (and the bulk itself!) is kind of emergent from the boundary theory.
A soul in tension that's learning to fly
Condition grounded but determined to try
Can't keep my eyes from the circling skies
Tongue-tied and twisted just an earthbound misfit, I
User avatar
twistor59
RS Donator
THREAD STARTER
 
Posts: 4966
Male

United Kingdom (uk)
Print view this post

Re: Farewell Feynman Diagrams?

#34  Postby iamthereforeithink » Sep 22, 2013 10:52 am

To me, it makes sense that space and time are emergent, rather than fundamental. It saves us from having to answer questions like "When did time begin?".
“The supreme art of war is to subdue the enemy without fighting.” ― Sun Tzu, The Art of War
User avatar
iamthereforeithink
 
Posts: 3332
Age: 9
Male

Country: USA/ EU
European Union (eur)
Print view this post

Re: Farewell Feynman Diagrams?

#35  Postby twistor59 » Sep 22, 2013 11:34 am

iamthereforeithink wrote:To me, it makes sense that space and time are emergent, rather than fundamental. It saves us from having to answer questions like "When did time begin?".


As far as I know (i.e. not very far!), in these holographic boundary theories, to date it's only spatial dimensions which they've been able to make emerge, not temporal ones.
A soul in tension that's learning to fly
Condition grounded but determined to try
Can't keep my eyes from the circling skies
Tongue-tied and twisted just an earthbound misfit, I
User avatar
twistor59
RS Donator
THREAD STARTER
 
Posts: 4966
Male

United Kingdom (uk)
Print view this post

Ads by Google


Re: Farewell Feynman Diagrams?

#36  Postby iamthereforeithink » Sep 22, 2013 1:45 pm

twistor59 wrote:
iamthereforeithink wrote:To me, it makes sense that space and time are emergent, rather than fundamental. It saves us from having to answer questions like "When did time begin?".


As far as I know (i.e. not very far!), in these holographic boundary theories, to date it's only spatial dimensions which they've been able to make emerge, not temporal ones.


Yes (AFAIK), but time seems to be entirely absent from these models. I'm not sure what that means. I'm also not completely clear about the implications of this particular geometric object. Apparently, it also does away with the need for virtual particles and "unitarity". How does it do that? When they say it does away with unitarity, do they mean that the probabilities don't sum up to one, or that probabilities are not needed at all?
“The supreme art of war is to subdue the enemy without fighting.” ― Sun Tzu, The Art of War
User avatar
iamthereforeithink
 
Posts: 3332
Age: 9
Male

Country: USA/ EU
European Union (eur)
Print view this post

Re: Farewell Feynman Diagrams?

#37  Postby twistor59 » Sep 22, 2013 3:02 pm

iamthereforeithink wrote:
twistor59 wrote:
iamthereforeithink wrote:To me, it makes sense that space and time are emergent, rather than fundamental. It saves us from having to answer questions like "When did time begin?".


As far as I know (i.e. not very far!), in these holographic boundary theories, to date it's only spatial dimensions which they've been able to make emerge, not temporal ones.


Yes (AFAIK), but time seems to be entirely absent from these models. I'm not sure what that means.


Nima's mantra is "spacetime is doomed". I think that just means he wants to formulate physics in a new set of variables in which spacetime doesn't appear. A bit like Roger Penrose's aim to formulate all of physics in twistor space. You can relate the end results back to spacetime by doing a certain transform, but all the calculations are done elsewhere, and the gain from doing this is that the calculations are easier!

iamthereforeithink wrote:
I'm also not completely clear about the implications of this particular geometric object. Apparently, it also does away with the need for virtual particles and "unitarity". How does it do that? When they say it does away with unitarity, do they mean that the probabilities don't sum up to one, or that probabilities are not needed at all?


I would imagine they mean that unitarity is "not manifest". i.e. if you look at the formalism, it's not obvious that all the probabilities add up to one. But if you looked harder and did lots of convoluted calculations, you'd find that unitarity was indeed respected.
A soul in tension that's learning to fly
Condition grounded but determined to try
Can't keep my eyes from the circling skies
Tongue-tied and twisted just an earthbound misfit, I
User avatar
twistor59
RS Donator
THREAD STARTER
 
Posts: 4966
Male

United Kingdom (uk)
Print view this post

Re: Farewell Feynman Diagrams?

#38  Postby newolder » Oct 03, 2013 3:55 pm

Lance Dixon/Sean Carroll blog post on "amplitudes'. The topic's work gets a brief mention too.
http://www.preposterousuniverse.com/blo ... mplitudes/
:thumbup:
Geometric forgetting gives me loops. - Nima A-H
User avatar
newolder
 
Name: Albert Ross
Posts: 6531
Age: 8
Male

Country: Feudal Estate number 9
Print view this post

Re: Farewell Feynman Diagrams?

#39  Postby DavidMcC » Oct 03, 2013 4:29 pm

I'm not sure that the "jewel-like geometric object" means that space-time is somehow unnecessary for the particles to exist in, and interact. I suppose it depends on your cosmology. In mine, particles are but excitations of space in the first place, so the latter would still be necessary.
May The Voice be with you!
DavidMcC
 
Name: David McCulloch
Posts: 14913
Age: 66
Male

Country: United Kigdom
United Kingdom (uk)
Print view this post

Re: Farewell Feynman Diagrams?

#40  Postby iamthereforeithink » Oct 03, 2013 5:41 pm

DavidMcC wrote:I'm not sure that the "jewel-like geometric object" means that space-time is somehow unnecessary for the particles to exist in, and interact. I suppose it depends on your cosmology. In mine, particles are but excitations of space in the first place, so the latter would still be necessary.


To each his own cosmology, I suppose.
“The supreme art of war is to subdue the enemy without fighting.” ― Sun Tzu, The Art of War
User avatar
iamthereforeithink
 
Posts: 3332
Age: 9
Male

Country: USA/ EU
European Union (eur)
Print view this post

PreviousNext

Return to Physics

Who is online

Users viewing this topic: No registered users and 1 guest