My friend, the theoretical physicist, believed so strongly in String Theory, "It must be true!" He was called to testify in a lawsuit, which contested the claims of String Theory against Quantum Loop Gravity. The lawyer was skeptical. "What makes you such an authority?" he asked. "Oh, I am without question the world's most outstanding theoretical physicist", was the startling reply. It was enough to convince the lawyer to change the subject. However, when the witness came off the stand, he was surrounded by protesting colleagues.
"How could you make such an outrageous claim?" they asked. The theoretical physicist defended, "Fellows, you just don't understand; I was under oath."
To believe without knowing it cannot be proved (yet) is the essence of physics. Guys like Einstein, Dirac, Poincaré, etc. extolled the beauty of concepts, in a bizarre sense, placing truth at a lower level of importance. There are enough examples that I resonated with the arrogance of my theoretical masters who were in effect saying that God, a.k.a. the Master, Der Alte, may have, in her fashioning of the universe, made some errors in favoring of a convenient truth over a breathtakingly wondrous mathematics. This inelegant lack of confidence has heretofore always proved hasty. Thus, when the long respected law of mirror symmetry was violated by weakly interacting but exotic particles, our pain at the loss of simplicity and harmony was greatly alleviated by the discovery of the failure of particle-antiparticle symmetry. The connection was exciting because the simultaneous reflection in a mirror and change of particles to antiparticles seemed to restore a new and more powerful symmetry—"CP" symmetry now gave us a connection of space (mirror reflection) and electric charge. How silly of us to have lost confidence in the essential beauty of nature!
The renewed confidence remained even when it turned out that "CP" was also imperfectly respected. "Surely," we now believe, "there is in store some spectacular, new, unforeseen splendor in all of us." She will not let us down. This we believe, even though we can't prove it.