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

Question about dimensions.

  1. Jul 24, 2011 #1

    How can they predict anything after dimension 7? Especially the part where they go from dimension 8 to 9.

    Isn't everything in that dimension supposed to be in-explainable by the our science and minds? And isn't dimension 8 a place of infinite starts? How can you go beyond the start?
  2. jcsd
  3. Jul 24, 2011 #2
    This video is an attempt to help you visualize extra dimensions. It isn't what the extra dimensions really are in any rigorous physical sense. In reality, there is no particular order to the dimensions and no distinction among them, except for the difference between space and time. (I'm speaking in general terms here -- in particular fundamental physical models there could be differences because of the way particular dimensions get wrapped up.) Nothing special happens at dimension 7, and things never become "inexplainable to our science and minds". In fact, a lot of physics right now is done dealing with 10 or 11-dimensional spaces, and mathematicians routinely deal with spaces of even higher dimensionality, even an infinite number of dimensions.
  4. Jul 24, 2011 #3
    So you're saying the beginning of the universe did not necessarily happen in the 7th dimension? Or that dimensions are simply a way of describing stuff, like numbers or letters?
    Last edited: Jul 24, 2011
  5. Jul 24, 2011 #4
    To be honest, I'm not even sure what that means. But if you're saying that the beginning of the world happened in the 7th dimension, but not in the 6th or the 8th or the first, I would say yes, that is wrong.

    Spacetime dimensions are a way of describing stuff, but they're more than just that. The question of whether space has 2 dimensions or 3 or 10 is a real physical question that can be answered experimentally. (At least in principle. The experiments to find out if there are more than 3 space dimensions are very hard to do.) The world would be a very different place if there were only two dimensions.
  6. Jul 24, 2011 #5
    Some physicists have put forth the holographic principle, which says the world has two spatial dimensions (if I'm understanding this correctly).

  7. Jul 24, 2011 #6
    True, and that's a very interesting idea. I guess I should have said that, if we live in a 2D universe, the laws of physics obeyed in that 2D universe are very different from those we are familiar with. According to the HP, the universe has equivalent descriptions as a 3D universe that obeys one set of physical laws, and a 2D universe (the boundary of the 3D universe) that obeys a different set of physical laws. But these laws are such that everything in one description maps to the other. No one knows how this would work with 3 and 2 dimensions, but Maldacena has produced an example of such a one-to-one correspondence between a 5D universe and its 4D boundary, which shows at least that the idea is not entirely crazy.

    Very cool stuff.
  8. Jul 27, 2011 #7
    By 'world' I meant the existence of physical laws as we know it; t=0 of the universe -- I'm sorry but imagining a t=0 kinda helps prevent my brain from exploding :D --.
    But I think I understand what you mean.

    I mistakenly made a relation between dimensions and time; automatically assuming that at t=0 the universe and all dimensions below seven existed. Its a bit of a logical enigma though, I am typically incapable of imagining anything without time, and the video stopped time after the 7th dimension my brain was like: "what the.. :uhh:".

    If I understood things correctly, what you mean is that:
    - All dimensions coexist without some dimensions having different characteristics of time than the others, time is measured the same in all dimensions.
    - All dimensions obey the physical structure known to us like photons, electrons, gravity...etc.
    - So in conclusion the string theory (and theories like 'dimensionless bits of data') could not mean that it is probable some universes exist with different physical principles from ours?

    Oh my God man that Wikipedia page made my brain itch a bit haha! But its a really good read.

    I'm really liking this stuff. Thanks for the help a lot.
  9. Jul 28, 2011 #8


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    When you embed a youtube video, the only thing you're supposed to type (or paste) between the tags is the code for the video. In other words, remove the = sign and everything to the left of it.

    This is a crackpot video. I think the moderators would have deleted your post if they had seen the video. It also doesn't belong in the set theory and logic forum.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook