If GUT are false, are string-based unification also false?

[ensabah6]

Are all string theory based unification of 4 forces predicated on GUT?

If GUTs (whether SU(5) to SO(10)) are all false, and not the way nature works, does this mean that string theory unification is also false?

 

[javierR]

The terminology "GUT" does not incorporate gravitation. In string unification you can have the couplings of all four interactions meet, with gravitation possibly joining in at a higher energy scale (near Planck scale typically). Nevertheless, if the GUT scale is at least a couple orders of magnitude less than the string scale, and you experimentally pushed the bounds to that scale, then the string theory could take over as the correct description of things and you could still try to achieve unification with it. Anyway, it's tough to rule out field theory GUTs since you can find ways of pushing the unification scale higher and suppress processes that aren't observed. (But this in turn affects cosmological arguments, which introduces additional constraints based on observations.)