Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A Emergent Gravity and the Dark Universe

  1. Nov 9, 2016 #1
    I just read about how professor Erik Verlinde saying that 'gravity is not a fundamental force of nature, but an emergent phenomenon. In the same way that temperature arises from the movement of microscopic particles, gravity emerges from the changes of fundamental bits of information, stored in the very structure of spacetime.'
    http://www.uva.nl/en/news-events/ne...ory-of-gravity-might-explain-dark-matter.html
    http://phys.org/news/2016-11-theory-gravity-dark.html
    So I was wondering what do YOU guys think about it? Does it make sense? Will he be able to 'prove' his theory? Will this become our new theory about the universe and such?
     
  2. jcsd
  3. Nov 12, 2016 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Verlinde talks about Entropic gravity - so gravity is to be modelled as emerging from the tendency for things to try to increase their entropy. Space itself is also emergent. See for example:
    https://arxiv.org/abs/1001.0785

    Also see in these forums:
    https://www.physicsforums.com/threads/erik-verlindes-new-view-on-dark-matter.755235/
    ... pretty much sums it up.

    ... not really a good question in science. It does not look immediately like some crackpot idea, but so what?
    Verlinder certainly believes he can make a good case for it.

    Short answer: nobody knows.

    afaict the theory has yet to produce any special predictions to distinguish it from general relativity... so, unless I missed something, there is no reason at present to suspect that it may be true or even useful.

    What a new theory like this needs to do is account for the old theories (which seems to be what the bulk of the papers I looked at are trying to do) and also have explanatory power in areas the old theories do not work well or at all. The second part seems sketchy at best. A new theory that explains everything the old theory does but no more is unlikely to get adopted.

    OTOH: it is probably too early to say that it is definitely not true. The default position is to remain skeptical until good evidence is forthcoming.

    Edit: more accessible expl of the usual debunk attempt: http://motls.blogspot.co.nz/2010/01/erik-verlinde-why-gravity-cant-be.html

    In 2012 he got 18million euros to fund an institute to work out the kinks in the theory.
    He gave a interview back then:
    http://www.uva.nl/en/news-events/ne...ew-with-prof.-erik-verlinde-introduction.html
    He says he’s working on explaining dark matter with his entropic gravity ideas. Progress seems slow, maybe because, as he says, "There are some small gaps in my reasoning and things that I still do based on intuition. I’m trying to fill in those gaps." Hum yeah... that's a red flag right there.

    He seems to have a decent publication/citation record:
    https://scholar.google.com/citations?user=Tm64-J0AAAAJ

    I havn't been through the citation on the entropic gravity stuff to see if they were supporting, or refuting.
     
    Last edited: Nov 12, 2016
  4. Nov 15, 2016 #3
    Watch Sean Carroll's video.



    He explains that even if you accept the findings and results of the recent papers, we STILL NEED dark matter and dark energy to explain what we observe,
     
  5. Nov 16, 2016 #4

    phinds

    User Avatar
    Gold Member
    2016 Award

    His argument about the exact variations in the acoustic ripples in the CMB are VERY convincing and something I had not heard before. Thanks for posting that @David Neves
     
  6. Nov 17, 2016 #5
    Good points by Carroll. In short, for Verlinde's theory to be plausible at all he has to first convince the science community they are wrong about the interpretation of the CMB's angular power spectrum as acoustic peaks of the last scattering surface. That's a tall order. Towards the end of Verlinde's paper there's a hint that he's going after expansion too in order to get rid of DM and DE. A bold guy this Verlinde.
     
  7. Dec 15, 2016 #6

    PeterDonis

    User Avatar
    2016 Award

    Staff: Mentor

    Some off topic posts have been deleted. Everyone please be aware of the PF rules on personal theories/speculations. Also please be aware that this is an "A" level thread, which assumes that anyone who posts in it has and can demonstrate a graduate level background, or the equivalent, in the subject matter. Posts will be moderated accordingly.
     
  8. Dec 15, 2016 #7

    atyy

    User Avatar
    Science Advisor

    There are indeed good indications that gravity and entropy are related. I have not seen any detailed development of Verlinde's vague ideas. However, there is the now classic work of Bekenstein, Hawking, and Jacobson, and the promising developments of those ideas in the context of the Maldacena's version of holography.

    https://arxiv.org/abs/1312.7856
    Gravitation from Entanglement in Holographic CFTs
    Thomas Faulkner, Monica Guica, Thomas Hartman, Robert C. Myers, Mark Van Raamsdonk

    https://arxiv.org/abs/1308.3716
    Gravitational Dynamics From Entanglement "Thermodynamics"
    Nima Lashkari, Michael B. McDermott, Mark Van Raamsdonk

    https://arxiv.org/abs/1609.00026
    Lectures on Gravity and Entanglement
    Mark Van Raamsdonk
     
  9. Dec 16, 2016 #8
    more like an alternative explanation.
     
  10. Dec 16, 2016 #9
    Carroll also admits he hasn't read Erik Verlinde paper.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Emergent Gravity and the Dark Universe
  1. Emergent Gravity IV (Replies: 37)

Loading...