PRIDE CHEKERAUnlike particles whose geodesics are world lines, strings move
along cylindrical world sheets, on which interactions don't occur
at points. Since strings are not point particles, string theory is
consistent with uncertainty principle, unlike nonrenormalizable
QFT which breaks at classical physics singularities, there are no
singularities in renormalizable relativistic QFT of one
dimensional objects.
That's why string theory is the only theory of high energy
remaining consistent with its spin-2 graviton. In this theory
physicists were able to have a grand unification, extra
dimensions, supersymmetry, chirality of gauge fields and
uniqueness.
Other physicists, such as Michio Kaku, co-expounder of the
String Field Theory, had been convinced that string theory is the
only best candidate of quantum gravity theory.
It had been enhanced into sub theories, Type 1, Type 2a and
Type 2b heterotic string theories, E8×E8, superstrings, bosonic
string theory, T, S and F dualities and its modern version M-
theory (membrane or matrix or mother are representations of
M).
We live in a 4D space-time world, but according to superstrings
space-time is 10D; as per Kaluza-Klein mechanism, we are in a
3D spatial universe, the other extra spatial 6D is muchly curled
up into microscopic Calabi-Yau manifolds beyond our view we
can’t detect. The 10th dimension is for time. Other theories even