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What if the world of dark matter was a mirror of our own, only with a set of broken rules? That could explain why dark matter appears to be so abundant but invisible, a new theory suggests.
Dark matter It is the mysterious and unknown substance that appears to make up the majority of all the mass in the universe; For every 2 pounds (1 kilogram) of normal matter, there are approximately 10 pounds (5 kg) of dark matter. It does not interact with light or normal matter. The only way scientists can detect it is through its subtle gravitational influence on normal matter, such as the movements of stars within galaxies and the growth of super large structures in cosmic time.
It might be easy to think that because matter and dark matter operate by different rules, one would be totally dominant over the other. But despite having wildly different properties, the amounts of normal matter and dark matter are still in the same ballpark. It seems like a strange coincidence. To explain this, scientists proposed that there could be some kind of hidden link between them. They published their research. January 22 in the preprint magazine arXiv.
The researchers postulated that for every physical interaction in normal matter, there is a mirror of it in the world of dark matter. This would be a new type of symmetry in nature, connecting the normal and dark matter worlds, the researchers said.
This symmetry would help explain why dark matter and regular matter have approximately the same abundance.
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In the article, the researchers point out another strange coincidence. In normal matter physics, a neutron and a proton have almost exactly the same mass, which allows them to bond and form stable atoms. If a proton were even slightly heavier, it would be totally unstable and would disintegrate in just a few minutes, making the formation of atoms impossible. In this imaginary scenario, the universe would be left with a sea of freely floating neutrons.
Perhaps, the researchers suggest, this imaginary, broken cosmos could be a reality in the dark matter mirror version of our universe. A special combination of physics led to a proton having approximately the same mass as a neutron; Perhaps in the dark matter mirror, that combination of physics played out differently, causing the “dark proton” to evaporate and leave behind a sea of ”dark neutrons,” what we identify as dark matter.
While this proposed mirror model allows for the possibility of rich interactions between dark matter particles (dark atoms, dark chemistry, and a dark periodic table of dark elements — there can’t be too much interaction, the researchers noted. If dark matter interacts a lot with itself, it would tend to clump together much more than scientists think. So most dark matter has to be relatively simple: a sea of free-floating neutral particles.
These additional interactions, which would be a dark mirror of our chemical world, may allow future scientists to test this theory. In the early universe, normal matter underwent nucleosynthesis, when the first elements were formed in a nuclear plasma. If this new idea is correct, then mirror nucleosynthesis also occurred in dark matter. In those early chaotic days, channels may have opened between the two worlds, allowing them to affect each other.
By carefully measuring the rate of element formation, something the next generation of cosmological observatories hopes to do, scientists can find evidence of one of these channels and glimpse the dark, mirror-like universe.