Tech UPTechnologyThere could be an 'anti-universe' going back in time

There could be an 'anti-universe' going back in time


What if… there was an anti-universe that has been going back in time since before the Big Bang? This is the theory put forward by a group of scientists in the journal Annals of Physics and that would provide a convincing explanation for the existence of the elusive dark matter, a mysterious but abundant substance that fills our universe ( and makes up 80% of the matter of the cosmos ).


What exactly does the theory say?

According to experts, this slightly far-fetched theory suggests that the early universe was small, hot and dense and uniform enough that time seemed symmetrical forwards and backwards. In this way, they would exist in parallel, our universe moving forward in continuous expansion and another twin universe, moving backwards. Time would go backwards, starting with the Big Bang.


What would imply the existence of an anti-universe?

If the new theory were true, the presence of a mirror anti-universe could mean that dark matter was not so mysterious, but simply a new type of phantom particle called a neutrino, and that there was no period of rapidly expanding “inflation”. the early universe.

This theory is based on what physicists call the three fundamental symmetries of nature. In the Standard Model of Particle Physics the three symmetries are: charge , because reversing the charge of a particle in a given interaction results in equal and opposite charge; parity, because the mirror image of an interaction of particles will look the same as the original; and time, because interactions that go back in time look the same as the original.

Physicists have never observed a violation of a combination of all three symmetries at the same time. If we take them all and change the charges, the mirror image to balance our universe but running backwards in time behaves exactly the same. Both universes obey CPT (charge, parity, and time) symmetry. Yes, they are symmetrical.

If we apply the CPT symmetry law to the entire universe, there must be a mirror image cosmos that balances our entire existence.


Thus, these three fundamental symmetries, the researchers say, suggest the existence of a mirror universe that would be the exact opposite of our own, meaning that it would be full of reflected and oppositely charged particles going backwards in time. Thus, the theory could provide an explanation for why physicists have never observed “right-handed” neutrinos . There are right-handed neutrinos somewhere that we can’t detect, as scientists have suggested in the past. Only three types of neutrinos have been observed, the electron neutrino, the muon neutrino, and the tau neutrino, and all of them rotate to the left with respect to their motion. These other right-handed neutrinos would be invisible but would influence the rest of the universe by interacting with gravity (much like dark matter).

The negative part of this theory

We could never access our twin universe or anti-universe because it exists “behind” our Big Bang, before ours in which we exist began.

How to check the theory?

As if we were in a movie from the Marvel universe focused on the multiverse, there are several factors that could lend credence to this theory outside of Doctor Strange and other scenarios. For example, if physicists could in the future conclusively measure the masses of neutrinos, and one of them turns out to be massless, it would greatly strengthen this theory of the existence of a backwards symmetrical universe. in the time.

Referencia: Latham Boyle, Kieran Finn, Neil Turok et al. The Big Bang, CPT, and neutrino dark matter. Annals of Physics, Volume 438, 2022, 168767, ISSN 0003-4916, DOI:

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