Can String Theory's Extra Dimensions Be Larger Than We Think?

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Discussion Overview

The discussion revolves around the nature of extra dimensions in string theory, specifically questioning whether these dimensions must be small and exploring the possibility of larger dimensions. Participants examine theoretical implications and interpretations of string theory regarding the scale of these dimensions.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants question whether the extra dimensions predicted by string theory must be small, suggesting that they could potentially exist within larger dimensions.
  • One participant asserts that dimensions are independent entities and cannot be contained within one another.
  • Another participant raises the idea that if string theory necessitates extra dimensions, there is no clear reason why these dimensions should be small compared to observable dimensions.
  • A reference to brane cosmology is made, indicating that there are versions of string theory that allow for larger extra dimensions.
  • A participant mentions a discussion in Hartle's GR textbook about the metric structure of small dimensions and their unnoticed nature in experiments.
  • One participant reflects on their evolving perspective regarding the size of extra dimensions, noting the influence of Randall and Sundrum's work on large extra dimensions and Maldacena's AdS/CFT correspondence.

Areas of Agreement / Disagreement

Participants express differing views on the size of extra dimensions in string theory, with no consensus reached on whether they must be small or if larger dimensions are a viable possibility.

Contextual Notes

Some discussions hinge on the definitions of dimensions and the implications of various theoretical frameworks, with unresolved questions about the nature and scale of extra dimensions in string theory.

Stanley Lee
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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?
 
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Dimensions are independent entities. A dimension cannot be inside of another dimension.
 
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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?
 
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.
 
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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