String theory was not invented to describe gravity; instead it originated in an attempt to describe the strong interactions, wherein mesons can be th… - David Gross

Physics is always a gamble; it is a game of exploration. That’s the fun of it. We never know for sure what will happen. Sometimes, we theorists can anticipate, but nature is the final judge.

Remarkably, the building of the Standard Model — the theory of how particles and forces interact — was the success of the conservatives. It required no revolution at the foundational level. Normal physics, the kind that goes on experiment after experiment, produced the Standard Model.

Why is space-time doomed? There are many reasons, among which: In string theory we can change the dimension of space-time by changing the strength of the string force. Thus, the so-called II-A string theory, which semi-classically describes closed strings moving in ten-dimensional flat space for very weak coupling is dual for strong coupling to a theory, called M-theory, that at low energies is described by eleven-dimensional supergravity. By increasing the string coupling we can grow an extra dimension. How can the spatial continuum be fundamental if the number of spatial dimensions can be so changed?