It seemed as if there was no end of strangeness. For the first time, as James Trefil has put it, scientists had encountered “an area of the universe that our brains just aren’t wired to understand.” Or as Feynman expressed it, “things on a small scale behave nothing like things on a large scale.” As physicists delved deeper, they realized they had found a world where not only could electrons jump from one orbit to another without traveling across any intervening space, but matter could pop into existence from nothing at all—“provided,” in the words of Alan Lightman of MIT, “it disappears again with sufficient haste.”

Perhaps the most arresting of quantum improbabilities is the idea, arising from Wolfgang Pauli’s Exclusion Principle of 1925, that the subatomic particles in certain pairs, even when separated by the most considerable distances, can each instantly “know” what the other is doing. Particles have a quality known as spin and, according to quantum theory, the moment you determine the spin of one particle, its sister particle, no matter how distant away, will immediately begin spinning in the opposite direction and at the same rate.