Uncommon Measure: A Journey Through Music, Performance, and the Science of Time

by Natalie Hodges

That idea of an instantaneous, prescient memory—of remembering the future, as it were—has a strange, surprising corollary in the natural world, in the universe’s order of things. It’s called the path integral, and it occurs in the realm of quantum mechanics: the sphere of the uncertain and statistical, with its tensions and overlappings between the finite and infinite, form and void. Defined by theoretical physicist Richard Feynman during the 1940s, the path integral calculates the probability that a given particle, occupying one position at a particular time, will end up at another position at a later time. The question seems simple enough, but it is complicated by the fact that quantum particles act as waves, and so their position, and the paths they take between positions, can only be described in terms of probability and not of fixity.