In the tapestry of 20th century physics, virtually every major thread is entangled with the name of Albert Einstein. He was most famous for the theory of relativity, of course, which rewrote Newton’s laws and set modern theoretical cosmology in motion. But Einstein also played a major role in the origins of quantum theory and in perceiving its weird implications — including entanglement, a mystery named by Erwin Schrödinger in a paper based on an experiment imagined by Einstein.
Entanglement is now one of the hottest research fields in physics. It is pursued not only for insights into the nature of reality, but also for developing new technologies, as Laura Sanders notes in a special section marking the 75th anniversary of Einstein’s entanglement paper (and another quantum legend, Schrödinger’s half-dead, half-alive cat).
Despite his contributions to quantum theory, Einstein didn’t like it. He believed that its weirdness indicated an