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

What Dimensions Are There (in Physics) ?

  1. Mar 23, 2010 #1


    User Avatar
    Gold Member


    I am curious about how many dimensions there are in physics. My physics teacher responded with '10 or 11'.

    -1 dimension: ???
    0th dimension: Fixed point
    1st dimension: Line
    2nd dimension: Flat plane
    3rd dimension: Object with depth on a flat plane.
    4th dimension: 3-dimensional with time
    5th dimension: ???
    6th dimension: ???
    7th dimension: ???
    8th dimension: ???
    9th dimension: ???
    10th dimension: ???
    11th dimension: ???

    I've tried googling it, but couldn't find any good answers...

  2. jcsd
  3. Mar 23, 2010 #2
    I never thought about negative dimensions!

    Anyway, you can think about the number of dimensions as how many numbers you need to represent a point in that space uniquely.

    So, for a two dimensional space, to specify a point, I would need two numbers (lets say, x and y). You can probably see how this is generalized.

    EDIT: As for answering your question... It depends on the physics you are doing. Physicists use anywhere from zero to infinite dimensions.
  4. Mar 23, 2010 #3


    User Avatar
    Gold Member

    Okay... so are 0, 1, 2, 3, and 4-dimensional universally accepted by physics? Are those the only dimensions universally accepted?
  5. Mar 23, 2010 #4


    User Avatar
    Gold Member

    I believe he means spatial/time dimensions
  6. Mar 23, 2010 #5
    In the standard model there are four.

    The 10 to 11 dimensions your professor was talking about is from string theory, an (incomplete) contender for the theory of everything.
  7. Mar 23, 2010 #6
    String theory predicts 11 dimensions:

    1. Up/Down
    2. Forward/Backward
    3. Left/Right
    4. Time
    5-11: Kaluza-Klein "curled up" dimensions.


    This is the easiest explanation I could find:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook