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Measuring extra-dimensions

I was watching a layman's documentary and it said:

"The 11th dimension is incredibly small, like a long tube about $10^-30m$ in diameter".

How can we know the general sizes of extra dimensions?

  • $\begingroup$ Note that $10^{-30}$ m is smaller than ay tool we currently use can measure. $\endgroup$ – dmckee --- ex-moderator kitten Jun 1 '12 at 12:49
  • $\begingroup$ I know, so how can we know the sizes of these dimensions? Given that we can't see them $\endgroup$ – ODP Jun 2 '12 at 15:44
  • $\begingroup$ @ODP: 11 dimention is just the theory no one has yet proved it, hence noone ever measured it $\endgroup$ – Xinus Apr 23 '17 at 11:03