If I have understood the basics of heterotic strings correctly, one requires a critical radius of compactified dimension to reconcile the apparent difference in spacetime dimension of left and right movers,

$$ R=\sqrt{\alpha} $$

Why would the radius of the compactified 16 dimensional torus be related to the string tension/length etc in such a way? They seem completely unrelated to me.

This post imported from StackExchange Physics at 2014-03-17 06:13 (UCT), posted by SE-user innisfree