Has the Einstein Revolution gone too far?

(FromDiscovery magazine)

...As Einstein extended his thinking from space and time to gravity, he found himself increasingly drawn to the power of the equation. “Never before in my life have I troubled myself over anything so much,” he wrote to a friend, “and I have gained enormous respect for mathematics, whose more subtle parts I considered until now, in my ignorance, as pure luxury!” The result of that effort, in 1916, was general relativity—the theory that had the newly confident Einstein telling God how the universe must work. By 1933 he had no doubts about the path to scientific truth. Delivering the Herbert Spencer Lecture at Oxford, he declared: “Our experience hitherto justifies us in believing that nature is the realization of the simplest conceivable mathematical ideas. I am convinced that we can discover by means of purely mathematical constructions the concepts and the laws connecting them with each other.”
Following Einstein’s example, subsequent physicists have discovered previously unimaginable phenomena: dark energy, black holes, the Big Bang. In trying to reconcile general relativity with quantum mechanics, theorists now invoke even more exotic things—subatomic strings, parallel universes, and higher dimensions. These latest concepts all exist beautifully in the mathematics, but so far observers have identified no sign of them in the real world.
Some scientists are starting to worry that Einstein’s revolution has gone too far. Without observation to check theory, at what point does the math devolve into game playing? Einstein, too, fretted about that possibility in his 1933 Oxford lecture. “Experience remains, of course, the sole criterion of the physical utility of a mathematical construction,” he said. How to move beyond slavish devotion to experience may have been Einstein’s greatest gift to the 20th century. How to bring mathematical imagination back down to earth may rate as his greatest challenge to the 21st.

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