Mar 21, 2022 I Paul Seaburn

Physicists Claim Anti-Universe Running Backwards Could Explain Dark Matter and Cosmic Inflation.

Here we go again with another popular science fiction convention potentially becoming a reality – only this time, it’s a big one. A new paper proposes that there exists an “anti-universe” which began at the Big Band and is a place where time run backwards, dark matter is different, particles are oppositely charged and Bizarro is the good Superman. OK, we’re not sure about the last one, but could the rest be true?

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Time running backwards?

“The universe before the bang and the universe after the bang may be viewed as a universe/anti-universe pair, emerging directly into the hot, radiation-dominated era we observe in our past. This, in turn, leads to a remarkably economical explanation of the cosmological dark matter.”

Proving that is the goal of the physicists who authored “The Big Bang, CPT, and neutrino dark matter,” soon to be published in the journal Annals of Physics (pre-published on It’s a concept far above this writer’s pay grade, but Live Science does a good job of simplifying the paper. Let’s see if we can bring it down one more notch to where we hang out. “CPT” are charge (C), parity (P) and time (T) – the three most important fundamental symmetries in nature. According to physicists, these three symmetries operate exactly the same in a mirror image state. In the paper, Latham Boyle, Kieran Finn and Neil Turok propose extending this symmetry from interactions between forces and fields to the entire universe. If that’s the case, then there should exist a mirror universe where everything is the opposite – including time running backwards -- yet works the same.

Mind blown? Let’s go back down to particles. The universe has three known types of neutrinos (extremely high-energy, low-density subatomic particles similar to electrons but without a positive nor negative charge) -- the electron-neutrino, muon-neutrino and tau-neutrino -- which all spin only to the left. This sets them apart form all other known particles which can spin to the right or the left. In a universe with CPT-symmetry, there would need to be right-spinning neutrinos. And, according to the paper, invisible right-spinning (or right-handed) neutrinos are what dark matter is probably made of.

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Which one is the anti-universe?

Still with us? Hoping you can travel to the anti-universe and meet your mirror image running backwards in time? Or Bizarro Superman? Unfortunately, the anti-universe existed before the Big Bang. If you’re disappointed, it’s worse for physicist depending on a fast-expanding (inflation) early universe for proof of theories – especially those looking the first (primordial) gravitational waves. In a CPT-symmetric universe, those waves don’t exist. Unfortunately, this can only be proven by not finding them.

Which is probably the same thing that will happen when we search for our mirror selves. And that’s probably a good thing – our real selves don’t look so hot to begin with.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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