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

Experimental evidence that confirms or points toward extraspatial dims

  1. Dec 13, 2006 #1
    Is there any experimental evidence that confirms or points toward extra spatial dimensions? I have been looking around for a bit, couldn't find anything.
  2. jcsd
  3. Dec 13, 2006 #2
    No there isn't. It is one of the things they will be looking for at the Large Hadron Collider, but so far all searches have been negative.
  4. Jan 2, 2007 #3
    What do you mean by a "dimension". In the strict mathematical sense a "dimension" is a variable. A "physical dimension" would be a physical variable or characteristic.

    One difficulty in dealing with the issue is that we are conditioned early in our education to believe that physical dimensions must be something like length, width and height. There is no logical reason that other physical characteristics cannot be dimensions. For example, force or energy characteristics are variables that could be treated as physical dimensions other than the 3 Euclidean dimensions. Gravity is an obvious characteristic that isn't consistent with length, width and height. The sun is larger than earth and has stronger gravity, but a black hole could be smaller than a basketball and still have much greater gravity.
  5. Jan 2, 2007 #4


    User Avatar
    Gold Member

    Note the original posting asks for "spatial dimensions", not plainly "dimensions" or "spaces"
    Last edited: Jan 2, 2007
  6. Jan 2, 2007 #5


    User Avatar
    Gold Member

    Now, the closest thing to experimental evidence is that the representations 1+5+10 of SU(5), and thus the representation 16 of SO(10), can be built from five fermionic generators (an idea from Wilczek and Zee). One could argue if these five generator are related to at least five extra dimensions, but such argument has never been written down in a formal paper.

    The next "experimental" argument is from Witten, who argued, around 1981-83, than the minimal space to incorporate an action of SU(3)xSU(2)xU(1) is seven-dimensional. You can call this argument "experimental" in the sense that it starts from the standard model group and not from any mathematial requisite of quantisation of an abstact setup (as string theory, for instance). Note that Witten argument requires a total of 11 dimensions instead of the 10 of string theory, so it was a justification for SuGra (in 11 dimensions) and a motivation for M-theory.
    Last edited: Jan 2, 2007
  7. Jan 17, 2007 #6
    In the applied mathematics of Game Theory, dimensions are considered alternative strategies.

    I have been reading a classic from the Society of Industrial and Applied Mathematics [SIAM]: Tamer Basar and Geert Jan Olsder. 'Dynamic Noncooperative Game Theory', revised 1999 from 1982. The authors refer to this as a type of representation theory.

    Since this is mathematics, the language is similar, but not identical to representation theory used in physics.

    Some differences include using C* for cost-to-come and G* for cost-to-go,

    Similarities include index sets, infinite topological structured sets, mappings and functionals in discrete time.

    There is substitution for some of these items in continuous time such as time intervals, Borel sets, trajectory, action and informational topological spaces.

    Tme appears to be treated as a duality.
    There may or not be stochastic influences.
    The Isaacs condition for the Hamiltonian is used.

    Types of such games include:
    for discrete time -
    OL - open loop
    CLPS - closed loop perfect state information
    CLIS - CL imperfect state
    FB - feedback perfect
    FIS - feedback imperfect
    1DCLPS - one-step delayed CLPS
    1DOS - one-step delayed obsevation sharing
    for continuous time -
    eta-DCLPS - eta-delayed DCLPS
    MPS - memoryless perfect state

    If players are allowed to be entities capable of exchanging enegy quanta or longevity then this might considered enegy economics?

    The stochastic game may be consitent with the probablistic nature of QM.

    Is phyisics failing to use a valluable tool of representation theory from applied mathematics?
  8. Jan 18, 2007 #7
  9. Jan 18, 2007 #8


    User Avatar
    Homework Helper

    This is if you assume that extra-dimensions are compactified and that gravity is not confined. In the warped spacetime of Randall and Sundrum, you can have "large extra-dimensions" without violating Newton's law.
    see for example: Phys.Rev.Lett. 83 (1999) 4690-4693 [hep-th/9906064]
  10. Sep 26, 2007 #9
    Kaluza-Klein Dimensions


    Could someone please tell me how many extra dimensions are needed to incorporate the strong and weak forces into the Kaluza-Klein model which has gravity at 4 dimensions and electro-magnetism at 5 dimensions?

  11. Sep 27, 2007 #10
    IMHO the masses are looking to far ahead, into the 6th, 7th, 8th, etc. Dimensions rather than focusing on the next obvious evolution.

    And to answer the original question.

    This is interesting-
  12. Sep 28, 2007 #11
    Think of a cause of quantum entanglement. So that this would be a cause that can act without varying at any distance between entangled quantum components so as to maintain the measured correlations in their forms of behaviour.

    Such a cause could not be described as surrounding objects in 3D space so where could it act but from additional spatial dimensions?
  13. Sep 29, 2007 #12


    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    This [quantum entanglement] is a bug in the wax of Einstein's universe. But in defense of DrE, QM was not yet a player. And QM does not diminish the importance of his 'new and improved' version of classical mechanics.
  14. Sep 29, 2007 #13


    User Avatar

    The DGP baneworld model also loosens the constraint on compactified extra dimensions, adding an extra infinite 5th bulk dimension:

  15. Sep 29, 2007 #14


    User Avatar
    Homework Helper

    sure.... there are many models out there.. perhaps one day we can create our own :smile:
  16. Sep 29, 2007 #15


    User Avatar

    Sure! Randall-Sundrum, by the way, does show departures from Newtonian gravitation. It's effectively a Yukawa-like potential due to the "warp factor" that attenuates the leakage into the bulk, albeit the deviations arise only at extremely small length scales (and not "sub-millimetre" as with the ADD model).
    Last edited: Sep 29, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Experimental evidence that confirms or points toward extraspatial dims
  1. Is there evidence of (Replies: 1)