When Tom became sick in the winter of 2003, we revisited the subject of quantum entanglement. It was early winter, and we sat in his small, comically messy apartment in Toronto, surrounded by jagged lightning-bolt towers of piled books. Dead insects and tendrils of cobweb and cat dander were heaped up in giant fuzzy swaths along the baseboards; the carpet erupted with geysers of dust at the slightest touch. The windows admitted only a diffused glow even at midday.
He wanted me to understand the concept of entanglement — how, once two subatomic particles have been part of the same nucleus, even if they’re subsequently separated by an enormous distance, they remain in a kind of sympathy with each another. A change in one produces an instantaneous change in the other. The notion captures the attention of quantum-physics enthusiasts because it suggests a kind of indivisibility of matter. It also seems to contradict Einstein’s insistence that nothing, not even information, can travel faster than the speed of light.