No, there aren’t parallel universes

Most science celebrities subscribe to it, but perhaps that should tell you everything you need to know.

Of course, I’m talking about the Many-Worlds Interpretation of physics.

Everettians

The idea traces back to a 1957 Ph.D. thesis by Hugh Everett III entitled On the Foundations of Quantum Mechanics. However, it was mostly ignored until 1970 when Bryce DeWitt resurrected it in an article Quantum Mechanics and Reality, appearing in Physics Today.

Since then, a growing number of physicists have subscribed to these ideas, many referring to themselves as Everettians.

Popularizations of the Many-Worlds Interpretation focus on the metaphors of a universe that “branches” into “parallel” worlds. This leads to all sorts of confusion.

Not only can you waste your money on a Universe Splitter app (which definitely doesn’t split anything), but physicists even argue amongst themselves at the level of these metaphors. Let’s call this kind of stuff Metaphorical Many-Worlds and not discuss it further.

Is there a better way to think about the Many-Worlds Interpretation than this? Yes — and the first thing we are going to do is stop calling it that.