The many-worlds theory, explained

A mind-bending, jargon-free account of the popular interpretation of quantum mechanics. First explored by the likes of Erwin Schrödinger and Hugh Everett, the idea that multiple universes exist alongside ours — or are created as a consequence of actions done in ours — has since inspired not only scientists and philosophers, but also artists and writers. For Everett, the Many Worlds Interpretation, or MWI, considers the "Universe 'splitting' into different versions of itself when faced with quantum choices, muddying the waters for decades." In this wonderful piece for The MIT Press Reader, John Gribbin gives us a detailed explanation of the MWI, and its conceptual evolution through the years. "Everett came up with the idea in 1955, when he was a PhD student at Princeton. In the original version of his idea, developed in a draft of his thesis, which was not published at the time, he compared the situation with an amoeba that splits into two daughter cells. If amoebas had brains, each daughter would remember an identical history up until the point of splitting, then have its own personal memories. In the familiar cat analogy, we have one universe, and one cat, before the diabolical device is triggered, then two universes, each with its own cat, and so on... But Everett did point out that since no observer would ever be aware of the existence of the other worlds, to claim that they cannot be there because we cannot see them is no more valid than claiming that the Earth cannot be orbiting around the Sun because we cannot feel the movement." This story was originally published in The MIT Press Reader in May 2020.