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Tiny dimensions question

  1. Jun 23, 2015 #1
    I hope I'm asking in the right forum. I'm trying to understand the subject of more dimensions a little better.
    Does the dimensions predicted by string theory have to be small?
    Can our known dimensions predicted by string theory actually be inside much larger dimensions?
  2. jcsd
  3. Jun 23, 2015 #2


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    Science Advisor

    Dimensions are independent entities. A dimension cannot be inside of another dimension.
  4. Jun 23, 2015 #3
    Yes, but the OP has raised a point about string theories which puzzle me too.
    If a string theory requires extra dimensions, why should these only be comparatively small in scale as compared to regular observable dimensions of space/time.
    Is a macromacro scale dimension or more, equally much of a possibililty?
  5. Jun 23, 2015 #4


    Staff: Mentor

  6. Jun 23, 2015 #5


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    Staff: Mentor

    Hartle's GR textbook has a one-page sidebar discussion of the metric structure of "tiny rolled-up dimensions" and why they would have escaped everyday notice and the attention of experimentalists to date. It's a good starting point for the subject.
  7. Jun 24, 2015 #6
    There was a time when I thought the focus on the extra dimensions being small was unnatural and biased. Then Randall and Sundrum came along with a scenario of large extra dimensions. And then Maldacena came up with AdS/CFT, a situation in which compact extra dimensions appear naturally (in the AdS side of the duality). That made me more accepting of the standard ideas about the extra dimensions.
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