Hey, it’s another quote from The Elegant Universe!
The history of physics is filled with ideas that when first presented seemed completely untestable but, through various unforeseen developments, were ultimately brought within the realm of experimental verifiability. The notion that matter is made of atoms, Pauli’s hypothesis that there are ghostly neutrino particles, and the possibility that the heavens are dotted with neutron stars and black holes are three prominent ideas of precisely this sort – ideas that we now embrace fully but that, at their inception, seemed more like musings of science fiction than aspects of science fact.
[…] string theory has been hailed as the most important and exciting development in theoretical physics since the discovery of quantum mechanics. This comparison is particularly apt because the history of quantum mechanics teaches us that revolutions in physics can easily take many decades to reach maturity. And compared to today’s string theorists, the physicists working out quantum mechanics had a great advantage: Quantum mechanics, even when only partially formulated, could make direct contact with experimental results. […] Unlike those who worked out quantum theory, today’s string theorists do not have the shining light of nature – through detailed experimental results – to guide them from one step to the next.
[…] The substantial number of physicists the world over who are vigorously pursuing string theory know that they are taking a risk: that a lifetime of effort might result in an inconclusive outcome. Undoubtedly, significant theoretical progress will continue, but will it be sufficient to overcome present hurdles and yield definitive, experimentally testable predictions? […] Only the passage of time will reveal the answers. The beautiful simplicity of string theory, the way in which it tames the conflict between gravity an quantum mechanics, its ability to unify all of nature’s ingredients, and its potential of limitless predictive power all serve to provide rich inspiration that makes the risk worth taking.