Einstein’s theory of relativity revolutionized our view of the universe, positing a space-time continuum undergirding all reality. Equally impactful has been quantum mechanics, which describe the behavior of subatomic particles in ways that differ from observable matter. But both theories have been verified by empirical observation and scientific experiments. String theory, and a select number of other theories that purport to explain the universe in one, all-encompassing equation, remain completely divorced from the physical world. Surely theories about the universe must relate directly to the matter in it?! Did Einstein get it wrong, or has groupthink led us down the wrong path for the last 40 years?
ERIC WEINSTEIN: In some ways we’ve been making amazing progress for 40 years—in my opinion—in the mathematics of field theory, which is the underlying geometric structure that undergirds both particle theory and general relativity.
So this has been an incredibly exciting time because this dictionary has opened up which ports all of the best insights from physics into differential geometry and from differential geometry back into physics.
So you’d be hard-pressed to say that nothing is happening. The problem is that we really wanted to quantize the geometry of general relativity but, in fact, what we ended up doing was geometrizing the quantum.
And so it’s been a bit of a disappointment for theoretical physicists who hoped that they would be living through a golden age of theoretical physics rather than the mathematics of theoretical physics.
So the field of particle theory has in some ways seemed to be advancing in terms of its mathematical underpinnings. But the elaborations on the standard model which is our specific understanding of the world in which we live has been all but stalled from the theory side since around 1973-1974.
So it’s a bit of a paradoxical situation and I think that, in part, we’ve never really been here before.
There was a period between about 1928 until the late 40s when theoretical physics had found quantum electrodynamics, the theory of electrons and photons, where most of the calculations we wanted to do gave infinite answers. The underlying theory seems sound. We just didn’t know how to get real contact with experiment.
And it took a long time for us to realize that we had a technical problem rather than a need for an absolutely fundamental revolution of the kind that brought us general relativity and quantum theory.
So I think that we’re a bit stuck and we don’t really know how long this very strange period is going to go on for, and this period has been dominated by the sort of quixotic hopes that one of a number of theories—whether it be super-symmetry theory, grand unified theory, technicolor or even noncommunicative geometry—might be our way out.
But the problem is that all of these highly speculative theories have remained in limbo and many of them have gotten rolled into this very strange complex of ideas that we call either string theory or M theory or some variant thereof.
And it is a question as to whether this is more of a physics-inspired theory or whether it’s really an economic and sociological phenomenon, which is that you have a generation that physicists in the baby boom who seem to be absolutely astounding geometers but appear to be wanting in terms of their ability to make contact with the natural world by the standards of previous generations.
And naturally that’s going to elicit some very strong feelings, because the idea that we would have had perhaps two generations let’s say in 40 years of physicists who can’t make contact with experimental reality with their theories is completely unprecedented in the modern era.