1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Dimensions vs Universes

  1. May 21, 2009 #1
    I always here talk of there being multiple universes or there being higher dimensions. When people use these terms are they referring to the same thing? If not, what's the difference?
  2. jcsd
  3. May 21, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi thepopasmurf! :smile:

    Higher dimensions refers to either

    i] spatial dimensions "outside" the universe, to "explain" how the universe is curved (for example, "the universe is like the surface of a balloon, and the universe expands the same way as a balloon expands, through an extra dimension") … these have no physical existence

    ii] spatial dimensions "outside" "our" universe, in which "our" universe is a "brane" floating around, and maybe sometimes hitting other universes … these (if they exist) do have physical existence

    iii] spatial dimensions "inside" the universe … these are "curled-up" dimensions, too small to see, in whch the strings of string theory vibrate :smile:

    Multiple universes either refers to ii] above, or to some weird quantum theory idea which is basically like "different time-lines" in science fiction (but respectable! :wink:)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook