# Brian Cox: Multiverse is a Simpler Explanation Than One Universe

Is the multiverse a more elegant explanation for physics than a single universe? University of Manchester physicist Brian Cox claims that the idea of multiple universes is ultimately a simpler explanation for certain effects of quantum mechanics.

Speaking on The Life Scientific, Cox explained that, on a fundamental level, nature is probabilistic. The laws of quantum mechanics, which explains the behavior of the most fundamental particles of the universe, tell us that all of the properties of a system cannot be simultaneously predicted with certainty, and that probabilities must be given for uncertain values. "Everybody agrees about that," said Cox.

This aspect of quantum mechanics is illustrated by the two-slit experiment. In this experiment, photons are sent through two slits in a plate, and the light passing through the slits is observed by a screen behind the plate. The wave interference patterns indicate that the photons do not have a location, per se, but the probability of detecting them can be expressed in a wave function that then "collapses" when the photons are observed. In other words, the particles take every path possible, but then our observation of the particles determines their path retroactively.

Cox illustrated the paradoxical nature of this concept with the famous example of Schrodinger's Cat. Erwin Schrodinger conducted a thought experiment that applies the concepts of quantum mechanics to a larger system. A cat inside an opaque box could either be alive or dead before it's observed, so it must be both dead and alive until it comes out of the box, at which point it would be observed as either alive or dead. This is clearly at odds with our observations of the behavior of large systems, such as cats, and is therefore a paradox.

Some physicists offer the multiverse as an alternative to wave function collapse. According to this theory, our observation doesn't retroactively determine the proton's path, which seems counterintuitive, but the particles have branched off into many different possible universes, and our observation of a single path is a function of our existence in a specific universe.

"That there's an infinite number of universes sounds more complicated than there being one," said Cox. "But actually, it's a simpler version of quantum mechanics. It's quantum mechanics without wave function collapse... the idea that by observing something you force a system to make a choice."

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