SUSY's Critical role in String Theory

Question

In many popsci articles it is claimed that String Theory (ST) birthed SUSY. Yet ST was originally invented as a bosons-only theory, that later on brought fermions into the fold. This was only possible After SUSY was incorporated. Hence the old moniker, Superstrings. My understanding is that string theory (ST) is a `house of cards' i.e., collapses & dies if SUSY is falsified. Is this true?

Answer 1

"Falsifying supersymmetry" is a phrase that has to be properly qualified. Our ability to falsify with experiment is limited. We can rule out the existence of supersymmetry only at accessible energy/distance/density scales. LHC, for example, is not able to resolve physics at distance scales much smaller than $\frac{\hbar c}{7\mbox{ TeV}} \simeq 300000000000000000 \mbox{ Planck lengths}$. It isn't seeing any supersymmetry, but that doesn't prove that physics isn't supersymmetric at about $1$ Planck length. (It does prove that some theoretical physicists made wrong predictions. Too bad for them. But that's actually what theorists normally do. You're doing quite well if you're right once.)

The existing versions of string theory require supersymmetry at roughly 1 Planck Length. We are not able to do the kind of experiment that rules out supersymmetry at this scale. (I personally find somewhat unconvincing the arguments that the string theories we know of are the only possible kind.)

Answer 2

Actually, no.

The supersymmetric transformations are elegant and simple ways of extending the Bosonic String theory to fermions, but if supersymmetry is falsified somehow, then maybe all of the discovered superstring theory would have to be discarded, but a new one may emerge... It would just use different supersymmetric transformations with different results.