A wild new theory suggests there may be an “other anti-universe,” running back in time before the Big Bang.
The idea posits that the early universe was small, hot, and dense — and so regular that time appears to be the same, going forward and backward.
If this is true, then the new theory Means that dark matter It’s not too mysterious it’s just a new flavor of a ghostly particle called a neutrino It can only exist in this kind of universe. The theory suggests that there would be no need for a period of rapidly expanding “inflation” in the young universe shortly after the Big Bang.
If true, future experiments to search for gravitational waves, or to determine the mass of neutrinos, could definitively answer whether such an anti-mirror universe exists.
Physicists have identified a set of fundamental symmetries in nature. The three most important symmetries are: charge (if you flip the charges of all particles involved in an interaction with the opposite charge, you’ll get the same interaction); parity (if you look at the mirror image of the interaction, you get the same result); and time (if you run an interaction back in time it will look the same).
Physical interactions are governed by most of these symmetries most of the time, which means that there are sometimes violations. But physicists have never noticed a violation of the set of all three symmetries at the same time. If you take every interaction observed in nature and flip the charges, take a mirror image, and run them back in time, then these interactions behave exactly the same.
This basic symmetry is called: CPT symmetry, for charge (C), parity (P) and time (T).
Related: What is the multiverse theory?
at new paper It was recently accepted for publication in Annals of Physics, and scientists are proposing to extend this common symmetry. Typically, this symmetry applies only to interactions – the forces and fields that make up the physics of the universe. But perhaps, if this symmetry is so important, it applies to the entire universe itself. In other words, this idea of this symmetry extends from a mere application of the “actors” of the universe (forces and fields) to the “phase” itself, the entire physical thing of the universe.
The creation of dark matter
We live in an expanding world. This universe is filled with many particles that do a lot of interesting things, and the evolution of the universe is moving forward over time. If we extend the concept of CPT symmetry to the entire universe, our view of the universe cannot be the whole picture.
Instead, there should be more. To maintain CPT symmetry throughout the universe, there must be an inverse-image cosmos that balances between us. This universe will all have more opposite charges than we have, flip in the mirror, and go back in time. We are just twins. Taken together, the two universes obey CPT symmetry.
Study researchers then wondered about the consequences of such a universe.
They found a lot of great things.
First, a CPT-respecting universe expands naturally and fills itself with particles, without the need for a prolonged period of rapid expansion known as inflation. While there is plenty of evidence for an event like inflation to occur, the theoretical picture of that event is incredibly vague. It is so vague that there is plenty of room for suggestions of viable alternatives.
Second, a universe that respects CPT will add a few more neutrinos to the mix. There are three known flavors of neutrinos: electron neutrino, muon neutrino, and tau neutrino. Oddly enough, all three flavors of neutrinos are left-handed (indicating the direction of their rotation relative to their motion). All other particles known in physics have different types of left and right handedness, so physicists have long wondered if there are additional right handed neutrinos.
A universe that respects CPT requires the presence of at least one type of right-handed neutrino. These species would be largely invisible to physics experiments, and would only affect the rest of the universe through gravity.
But the invisible particle that engulfs the universe and interacts only by gravity is very similar to dark matter.
The researchers found that conditions imposed by obeying CPT symmetry would fill our universe with right-handed neutrinos, enough to explain dark matter.
Predictions in the mirror
We will never be able to reach our twin, the CPT mirror universe, because it exists “behind” the Big Bang, before our universe began. But that doesn’t mean we can’t test this idea.
The researchers found some notable results for this idea. For example, they predicted that the three known types of neutrinos should all be Majorana particles, which means that they are their antiparticles (as opposed to regular particles like the electron, which have isotopes of antimatter called positrons). So far, physicists are not sure whether or not neutrinos have this property.
In addition, they expected one type of neutrino to be massless. At the moment, physicists can only set upper limits for neutrino masses. If physicists can definitively measure neutrino masses, and one of them is already massless, that would greatly enhance the idea of a CPT symmetric universe.
Finally, in this model 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. But in a CPT symmetric universe, no such waves should exist. So if the searches for primordial gravitational waves are empty, this could be a clue that this CPT mirror universe model is correct.
Originally published on Live Science.
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