The mirror universe What if our twin universe was going against time?

The sad part is that we won't be able to reach our twin universe because it is "behind" the Big Bang, before our universe began, but that doesn't mean we can't test this idea.

What if our twin universes were going back in time? Although this sounds absurd, scientists believe that the existence of such a mirror universe may explain many of the mysteries about our universe in which we live.

A wild theory suggests that there may be an "anti-universe" stretching back in time before the Big Bang. The "anti-universe" theory - which was outlined in a paper accepted for publication in the Annals of Physics - posits that the first universe was small, dense, very hot, and regular to the point that time, whether moving forward or backward, would appear the same.

This theory could help demystify dark matter, which has long been thought to be very mysterious. If our universe actually has a twin that goes back in time, then dark matter is basically a different version of a particle called a "neutrino" that can only exist in this double universe.

In addition, the theory assumes that the universe did not go through a period of "inflation" after the Big Bang in which a massive expansion occurred. If this is true, then future experiments to search for gravitational waves, or to determine the mass of neutrinos, could definitively answer whether or not this mirror universe exists.

What is the reason for postulating this anti-universe?

This concept of an anti-universe, which the new paper attempts to present, indicates that the reason for the assumption of this universe is that there is a fundamental symmetry in nature, primarily symmetry of charge, parity and time. This basic symmetry is known as CPT symmetry, where C stands for charge, P for valence, and T for time.

Scientists assumed that to maintain this symmetry of charge, parity and time in the universe, we must have an inverted cosmic picture to balance our universe, as stated in a report published in the "Live Science" website.

Physical interactions are generally governed by this symmetry, but physicists have never observed a violation of these laws of nature simultaneously; So the researchers hypothesize that while this symmetry applies to interactions, it can also apply to the entire universe.

As such, to maintain this symmetry, there can be an inverse cosmic picture to balance our universe. If we take this into account, and both universes are subject to charge, parity and time symmetry, this means that there will be an invisible particle affecting the universe through gravity, which is very similar to dark matter.

consequences of this universe?

Study researchers then wondered about the consequences of such a universe. They found a number of things:

First, a universe that includes charge, parity and time symmetry expands naturally and fills itself with particles, without the need for the prolonged period of rapid expansion known as "inflation".

While there is plenty of evidence that the inflation event occurred, the theoretical picture of that event is largely ambiguous. Inflation is so vague that there is plenty of room for viable alternative proposals.

Second, a universe that includes charge, parity, and time symmetry would add some extra neutrinos to the mix already in the universe. There are 3 known neutrinos: the electron-neutrino, muon-neutrino, and tau-neutrino. Oddly enough, all three types of neutrinos are left-handed (in reference to the direction rotation relative to its motion).

There are 3 types of neutrinos: electron neutrino, tau neutrino, and tau neutrino (Uric Alert - University of Washington).

So physicists have long wondered if there are extra neutrinos in the right hand, especially since all other particles known in physics have different types of left and right handedness.

Third, a universe that includes charge, parity, and time symmetry requires the presence of at least one type of right-handed neutrino, which would be largely invisible to physics experiments, and would only affect the rest of the universe through gravity, much like dark matter.

The researchers found that, given the symmetry of charge, parity and time, the right-handed neutrinos would fill the universe, which is enough to explain dark matter.

Can our twin universe be reached?

The sad part is that we won't be able to reach our twin universe, because it is "behind" the Big Bang, before our universe began, but that doesn't mean we can't test this idea.

Scientists expected that one of the types of neutrinos in the anti-universe would be massless, and therefore if physicists could definitively measure the masses of neutrinos, and one of them was already massless, this would greatly enhance the idea of ​​an anti-symmetric universe.

Finally, in this new model of the anti-universe, the inflation event never occurred; Instead, the universe naturally filled up with particles on its own. Physicists believe that inflation shook space-time to such an extent that it swamped the universe with gravitational waves.

Several experiments are underway to search for these primordial gravitational waves. In the event that scientists are not able to monitor them, this is further evidence of the correctness of the anti-symmetric universe model, which says that these waves should not exist because there was no inflation in the first place.