M-Theory Through the Looking Glass: Tachyon Condensation in the E_8 Heterotic String

Understand

We study the spacetime decay to nothing in string theory and M-theory.

• First we recall a nonsupersymmetric version of heterotic M-theory, in which bubbles of nothing -- connecting the two E_8 boundaries by a throat -- are expected to be nucleated.
• We argue that the fate of this system should be addressed at weak string coupling, where the nonperturbative instanton instability is expected to turn into a perturbative tachyonic one.
• We identify the unique string theory that could describe this process: The heterotic model with one E_8 gauge group and a singlet tachyon.