A wild new theory suggests that our Universe is not the only one that exists but that it has a twin, although not a completely equal one, but a kind of ‘anti-universe’ where everything is upside down and therefore, time goes backward. This theory, which is about to be published in the journal Annals of Physics, would explain the existence of dark matter and would also imply that there was also no need for the period of inflation that dramatically expanded the size of our primordial cosmos, just after the Big Bang.
The supreme trinity of symmetries
From the point of view of Particle Physics, there is a set of fundamental symmetries in nature, but within these, there are three that are positioned as the most important. One of them is charges; if you change the charges to their opposites of all particles involved in an interaction, you will get the same interaction. Secondly, we have parity; if you look at the mirror image of interaction, you get the same result. Finally, there’s time. If you run an interaction backward in time, it will look the same.
Most particle interactions obey this trinity of symmetries most of the time, which means that there are violations of them. However, a simultaneous violation of these three, which together form a fundamental symmetry called CPT symmetry (charge, parity, and time), has never been observed.
This is why scientists believe that, if we extend this concept of CPT symmetry to our entire cosmos, then our view of the Universe is incomplete, there is something else out there that we cannot observe. That is, if you take all the interactions occurring in nature and change their charges, take the mirror image and run it backward in time, the interactions will behave the same. This is precisely what happens in the anti-universe, the twin of our great cosmos where everything behaves in the same way but with opposite charges, in mirror images and in the opposite direction of the arrow of time.
What this anti-universe would be like
After arriving at the hypothesis of the anti-universe, the researchers wondered what would be the consequences of the existence of the twin but opposite to our home, and this is where dark matter comes to the fore. According to their calculations, a universe respecting CPT symmetry would add some neutrinos to the particle soup.
Three flavors of neutrinos are currently known: electron, muon, and tau, but all three are known to be left-handed, i.e., left-handed spinning. This is strange considering that all other particles are known to have variations in their spins; all known particles have left- and right-handed variations, except for the neutrino. This situation has generated doubts among physicists who wonder if there are missing right-handed neutrinos that we have not yet been able to discover.
A universe consistent with CPT symmetry should add at least one right-handed neutrino to the particle catalog, the authors say. This species would be largely invisible to particle physics experiments and would only influence the rest of the Universe through gravity. Eureka! If this theory is confirmed, it could mean that dark matter is not as mysterious as previously thought but is a neutrino of unknown flavor that is invisible but has a great influence on the Universe.
Unfortunately, even if this theory were proven, we would never have direct access to our mirror twin, since it exists ‘behind’ the Big Bang and the birth of the cosmos. However, its existence can still be proven by the influences it has on this side of the mirror. And although there is still a long way to go to understand the behavior of the cosmos, the emergence of wild theories like this one, gives us back the enthusiasm to continue investigating reality.
Text courtesy of Ecoosfera
