“In quantum physics, if two particles interact in a certain way and then become separated, regardless of how distant they are from each other they will share a state known as ‘quantum entanglement.’ That is, they will keep sharing information despite their separation. This theory used to upset Einstein. In his theory of relativity, no transmission of information could occur faster than the speed of light, therefore he couldn’t understand how the two particles could be simultaneously connected.”—Riccardo Giacconi