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What are all the Dimensions?

  1. Oct 30, 2003 #1
    I'm just curious, and since I'm not having any luck on Google searches; I decided to ask the PF and Mkaku forum.

    What are the names for all the 11 Dimensions? Or do they even have given, scientific names? Just wondering.

    Oh and one more thing. Does the new hypothesis of the Universe being a dodecahedron have any spin or affect on the 11d theory?

  2. jcsd
  3. Oct 30, 2003 #2


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    The higher dimensions don't have names. In physics the three common names length, width, and height are rarely used since the objects concerned can easily be rotated into any coordinate system without changing the physics. So when you go up to Minkowski space you just have the distinction between time and the three spacelike dimensions. Similarly in string theory, time is distinguished from the 9 or 25 or whatever spacelike dimensions. Sometimes they work in what is called the lightcone gauge, in which time ans one space dimension are singled out, and then the remaining space dimensions are called transverse dimensions.

    This is about as far as naming goes. Once you get used to replacing x, y, and z by x1,x2,... the naming thing soon becomes uninteresting.
  4. Oct 30, 2003 #3
    Hehehe. Okay, just making sure. Thanks for the insight.
  5. Nov 8, 2003 #4
    The high dimension everywhere

    As the mass complex everywhere, the dimension more than 4 is everywhere so. It is not important about dimension number, the important is in a unit and some phys means in the same dimension unit.
  6. Dec 23, 2003 #5
    Well, movement in the 5th dimension is sometimes referred to as "ana" and "kata", though I can't remember who coined it.
  7. Dec 23, 2003 #6
    My understanding is that some of the dimensions were added to the model because of forces. It was suggested that light could be caused by something vibrating in a dimension other than our three, thus creating these energetic "waves" in our three dimensional space. The only puzzling thing about that theory is that, when photons are produced, they don't move in waves such as in water rippling, but more like waves on the beach, only without the returning motion.
    I believe that some suggestions have been made on the relationship between gravity and other dimensions that relates to the curavture of space time and the like. I'm not exactly sure what led to the precise numbers of dimensions that have been proposed so for, perhaps someone else can shed some light on this.
  8. Dec 23, 2003 #7


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    The dimensionality of spacetime is actually a variable in string theory. In the various different kinds of string theory you can solve for the variable. In bosonic string theory (the oldest kind )it comes out 26. In supersymmetric string theory it comes out 10. M-theory builds an extra dimension on superstring theory, for a total of 11. One of these is a time coordinate in each case, and the others are spacelike.
  9. Dec 23, 2003 #8
    I believe Charles H. Hinton coined them, and they are the greek prepositions meaning "up" and "down". Some people use the terms "upsilon" and "delta" (favored by Clifford A. Pickover). For directions relative to the orientation of an object (like left & right), i use the words "zant" and "wint" coined by Jonathan Bowers - see my glossary:

    Fourth Dimension Glossary
  10. Dec 23, 2003 #9


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    alkaline, that's a very nice site on the fourth (and higher) dimension.

    I notice you say there are two independent kinds of rotation in tetraspace. At least that's what I thought you said. Is this related to the fact that SU(4) = SU(2) X SU(2)?
  11. Dec 23, 2003 #10
    thanks :-)

    it's possible for an object to have two independent rotations at the same time. There is only one "kind" of rotation in the fourth dimension - everything rotates around a plane. I'm not sure what the SU(n) notation means - i could answer your question if you explained it.
  12. May 28, 2004 #11
    I think of the extra dimensions as lower not higher d's. In other words, a sphere represents the three(3) whole dimensions plus time and the sub-dimensions in 10D space includes the following subsets;
    = angular momentum =
    5 - 60 degrees
    6 - 120 degrees
    7 - 180 degrees
    8 - 240 degrees
    9 - 300 degrees
    10 - 360 degrees

    Each represents a change in direction of angular momentum.
  13. May 28, 2004 #12


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    Why just these multiples of 60? There is a continuum of angles in a circle, so by your idea that's a nondenumerable infinity of new dimensions!
  14. May 29, 2004 #13

    hi Self,
    I guess I should have stated that this concept refers to the most fundamental state of energy incorperated within the string. If the string turns out to consist of a tubular shape, then the angles refered to would be limited to this confined area. Of course, I'm assuming the string is of a pure energy state.
    My research addresses the goal of unification from the bottom up. I'm designing a model of the cosmos based on the assumption that there is only one fundamental force and all of the known forces are secondary. Although my methodology deviates somewhat from tradition, I always follow strict guidelines base on known facts and accepted theories.
    Thanks for your response.
  15. May 30, 2004 #14


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    Well, good luck. Many have tried that but with no useful results. If you want to post more details about your theory you should do it on the Theory Development forum.
  16. May 30, 2004 #15
    We may not be able to detect the higher dimensions with our senses but perhaps
    our senses exist in them and this is what separates conscious experience from unconscious experience - awareness from sleep.
  17. May 30, 2004 #16
    What is the Metric in Superstringtheory:)

    or at least, develope the concept :smile:


    So if we added an extra compact space dimension to our three existing noncompact space dimensions, then D=4, but D-2=2, so the force law is still an inverse square law. The Newtonian force law only cares about the number of noncompact dimensions. At distances much larger than R, An extra compact dimension can't be detected gravitationally by an altered force law.

    The effect of adding an extra compact dimension is more subtle than that. It causes the effective gravitational constant to change by a factor of the volume 2pR of the compact dimension. If R is very small, then gravity is going to be stronger in the lower dimensional compactified theory than in the full higher-dimensional theory.

    So if this were our Universe, the Newton's constant that we measure in our noncompact 3 space dimensions would have a strength equal to the full Newton's constant of the total 4-dimensional space, divided by the volume of the compact dimension.

    That's an important detail, because the size of the gravitational coupling constant is what determines the distance scale of quantum gravity. So the distance scale of quantum gravity has to be very carefully defined in theories with compactified extra dimensions.


    I am trying to remain consistent with these ideas as well, and it is very hard sometimes to maintain these concepts in light of the theoretical demands new paradigmal models, that are placed before us.
    Last edited: May 30, 2004
  18. May 30, 2004 #17
    last comment on this subject

    Would it not be possible to consider the radius to be the variable and not the degree of angular momentum versus direction?

    Sorry for making reference to the source of my comments. I will not comment any further on this subject unless prompted.
    Thanks for the advice.
  19. May 30, 2004 #18
    The familiar extended dimensions, therefore, may very well also be in the shape of circles and hence subject to the R and 1/R physical identification of string theory. To put some rough numbers in, if the familiar dimensions are circular then their radii must be about as large as 15 billion light-years, which is about ten trillion trillion trillion trillion trillion (R= 1061) times the Planck length, and growing as the universe explands. If string theory is right, this is physically identical to the familiar dimensions being circular with incredibly tiny radii of about 1/R=1/1061=10-61 times the Planck length! There are our well-known familiar dimensions in an alternate description provided by string theory. [Greene's emphasis]. In fact, in the reciprocal language, these tiny circles are getting ever smaller as time goes by, since as R grows, 1/R shrinks. Now we seem to have really gone off the deep end. How can this possibly be true? How can a six-foot tall human being 'fit' inside such an unbelievably microscopic universe? How can a speck of a universe be physically identical to the great expanse we view in the heavens above? (Greene, The Elegant Universe, pages 248-249)
  20. May 30, 2004 #19
    Bubble of Nothing:But those are not the only new states in the Kaluza-Klein spectrum. The g44 component of the metric propagates as a massless scalar field f(xa) in the noncompact dimensions. This would result in a new long range force not observed in Nature.

    I believe Witten addressed this?
  21. May 30, 2004 #20


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    By [tex]G_{44}[/tex] I presume you mean the time-time component, what others call [tex]G_{00}[/tex]. Note that general covariance means that individual components of tensors are not preserved under general coordinate changes, so to tag this as a field (presumably existing prior to coordinate choices) is dubious in the extreme.
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