For more than ten years, my theory was in limbo. Then, finally, in the late 1980s, physicists at Princeton said, 'There's nothing wrong with this theory. It's the only one that works, and we have to open out minds to hyperspace.' We weren't destined to discover this theory for another 100 years because it's so bizarre, so different from everything we'd been doing. We didn't use the normal sequence of discoveries to get to it.
Describing reaction to his superstring theory of hyperspace which mathematically relates the universe's basic forces.

String theory is 21 st century physics that fell accidentally into the 20th century.

Superstring theories provide a framework in which the force of gravity may be united with the other three forces in nature: the weak, electromagnetic and strong forces. Recent progress has shown that the most promising superstring theories follow from a single theory. For the last generation, physicists have studied five string theories and one close cousin. Recently it has become clear that these five or six theories are different limiting cases of one theory which, though still scarcely understood, is the candidate for superunification of the forces of nature.

There are 60 sub-atomic particles they've discovered that can explain the thousands of other sub-atomic particles, and the model is too ugly. This is my analogy: it's like taking Scotch tape and taping a giraffe to a mule to a whale to a tiger and saying this is the ultimate theory of particles. ... We have so many particles that Oppenheimer once said you could give a Nobel Prize to the physicist that did not discover a particle that year. We were drowning in sub-atomic particles.
Now we realize that this whole zoo of sub-atomic particles, thousands of them coming out of our accelerators, can be explained by little vibrating strings.