Notices
Results 1 to 14 of 14
Like Tree2Likes
  • 1 Post By Dywyddyr
  • 1 Post By Markus Hanke

Thread: Latest Paper by T. Padhmanaban may 2014

  1. #1 Latest Paper by T. Padhmanaban may 2014 
    Suspended
    Join Date
    Sep 2013
    Posts
    475
    Here is the link :

    http://arxiv.org/pdf/1405.5535v1.pdf

    ABSTRACT

    "I show that in a general, evolving spacetime, the rate of change of gravitational
    momentum is related to the difference between the number of degrees of freedom in
    the bulk and the boundary of a region. This expresses the gravitational field equa-
    tion in the thermodynamic language (in contrast with the conventional geometric
    language) which is the natural description, if gravity is an emergent phenomenon.
    In all static spacetimes, the number of degrees of freedom in the boundary is equal
    to the number of degrees of freedom in the bulk; i.e., these spacetimes maintain
    holographic equipartition. It is the departure from holographic equipartition that
    drives the time evolution of the spacetime. This result, which is equivalent to
    Einstein’s equations, provides an elegant, holographic, description of spacetime
    dynamics."


    CONCLUSION

    "This strengthens the idea
    that gravitational field equations have the same conceptual status as the equations of
    thermodynamics or fluid mechanics, with the Davies-Unruh temperature providing the
    link between microscopic and macroscopic descriptions of spacetime. It is remarkable
    that the dynamical evolution of the spacetime can be described in such an elegant,
    holographic language which is closer to thermodynamics than to geometry."




    >> I'm interested in your reactions on this paper.


    Last edited by Noa Drake; May 29th, 2014 at 02:26 PM.
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Professor Daecon's Avatar
    Join Date
    Jul 2013
    Location
    New Zealand
    Posts
    1,288
    What's it about?


    Reply With Quote  
     

  4. #3  
    Genius Duck Dywyddyr's Avatar
    Join Date
    Jan 2013
    Location
    Scunthorpe, UK
    Posts
    11,992
    Quote Originally Posted by Daecon View Post
    What's it about?
    It's about 6 pages.
    shlunka likes this.
    "[Dywyddyr] makes a grumpy bastard like me seem like a happy go lucky scamp" - PhDemon
    Reply With Quote  
     

  5. #4  
    Suspended
    Join Date
    Sep 2013
    Posts
    475
    Quote Originally Posted by Daecon View Post
    What's it about?
    I added the abstract and the conclusion to give you an idea.
    Reply With Quote  
     

  6. #5  
    Anti-Crank AlexG's Avatar
    Join Date
    Mar 2012
    Posts
    2,809
    I noticed that out of the 5 references in the paper, one was from 1975, and the other 4 he was referencing himself. All his self-references were to papers on arvix, none of which was peer reviewed.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
    Reply With Quote  
     

  7. #6  
    Suspended
    Join Date
    Feb 2013
    Posts
    1,774
    Quote Originally Posted by AlexG View Post
    I noticed that out of the 5 references in the paper, one was from 1975, and the other 4 he was referencing himself. All his self-references were to papers on arvix, none of which was peer reviewed.
    No, look more carefully, all of his references are published . In very reputable journals. He simply gives the arxiv link as an addition.
    Reply With Quote  
     

  8. #7  
    Suspended
    Join Date
    Sep 2013
    Posts
    475
    This paper is a continuation on his larger 2009 paper 'Thermodynamical aspects of gravity : new insights', containing 150 references, only a very small portion being his own papers. In turn that 2009 paper was an important reference in Erik Verlindes 2010 paper 'On the origin of gravity and the laws of Newton, and an influence on his work after 2010.
    Reply With Quote  
     

  9. #8  
    Anti-Crank AlexG's Avatar
    Join Date
    Mar 2012
    Posts
    2,809
    I stand corrected.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
    Reply With Quote  
     

  10. #9  
    Brassica oleracea Strange's Avatar
    Join Date
    Oct 2011
    Location
    喫茶店
    Posts
    17,036
    ei incumbit probatio qui dicit, non qui negat
    Reply With Quote  
     

  11. #10  
    Moderator Moderator Markus Hanke's Avatar
    Join Date
    Nov 2011
    Location
    Ireland
    Posts
    7,302
    Just a few comments here. Firstly, Thanu Padhmanaban is one of the foremost experts on gravitational physics alive today. His textbook "Gravitation: Foundation and Frontiers" is well on track to become a standard text alongside MTW and Wald, although it must be said that it is highly technical and definitely not your run-of-the-mill undergrad text. In any case, he is a genuine researcher and brilliant academic, albeit not one who is widely known outside academic circles.

    >> I'm interested in your reactions on this paper.
    I closely follow both gr-qc and hep-th on arXiv, and Padhmanaban is in my favourites along with a few others, so I read this paper when it was first uploaded. It is very interesting, though many of the details elude me for lack of mathematical knowledge; however, it goes along very nicely with some of the things I had mentioned on your other thread. The basic idea of this paper is that the future-oriented foliation of hypersurfaces ( i.e. the "succession of moments of time" ) arises from a relationship between a hypervolume and its surface, called the holographic equipartition principle. I would lie if I said I understand everything involved in this, but basically what he is pointing out that there is a link between macroscopic gravitation and the microscopic structure of the vacuum given by Unruh radiation, i.e. the fact that accelerated observers see a different vacuum ground state.

    Padhmanaban has been working on these ideas for some time, so this paper is an elaboration on previous proposals.
    Howard Roark likes this.
    Reply With Quote  
     

  12. #11  
    Moderator Moderator Markus Hanke's Avatar
    Join Date
    Nov 2011
    Location
    Ireland
    Posts
    7,302
    I forgot to mention the following - while there are remarkable parallels between gravity and thermodynamics, Verlinde's original idea of "entropic gravity" appears to be in conflict with experimental data. I wasn't aware of this until KJW pointed it out a while back, but the paper outlining this seems quite convincing :

    http://alpha.sinp.msu.ru/~panov/Lib/...009.5414v1.pdf
    Reply With Quote  
     

  13. #12  
    Suspended
    Join Date
    Sep 2013
    Posts
    475
    It seems that this is an ongoing discussion
    with arguments and counter arguments

    http://arxiv.org/pdf/1104.4650v2.pdf
    Reply With Quote  
     

  14. #13  
    Moderator Moderator Markus Hanke's Avatar
    Join Date
    Nov 2011
    Location
    Ireland
    Posts
    7,302
    Quote Originally Posted by Noa Drake View Post
    It seems that this is an ongoing discussion
    with arguments and counter arguments

    http://arxiv.org/pdf/1104.4650v2.pdf
    Interesting I'd call it a healthy debate !
    Reply With Quote  
     

  15. #14  
    Suspended
    Join Date
    Sep 2013
    Posts
    475
    Healthy debate ! Excellent.
    Reply With Quote  
     

Similar Threads

  1. Replies: 0
    Last Post: April 24th, 2014, 03:50 AM
  2. Sochi 2014
    By RomanK in forum General Discussion
    Replies: 17
    Last Post: February 25th, 2014, 05:51 PM
  3. Your best wishes 2014
    By Estheria Quintessimo in forum General Discussion
    Replies: 1
    Last Post: December 26th, 2013, 06:06 PM
  4. 2014 Conferences
    By InternationalASET in forum General Discussion
    Replies: 0
    Last Post: December 5th, 2013, 01:58 PM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •