What does it mean by “if neutrinos are their own anti-particle, it explains why the universe exists”?

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Confused after reading the following article.

https://www.cbc.ca/radio/ideas/particle-astrophysics-studying-origin-of-universe-1.6733153

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Anonymous 0 Comments

As far as scientists can figure out, there is fundamentally no difference between matter and antimatter, other than the reversed charges. They have the same mass, have the same interactions with gravity and the other forces, they have the same charge strength (just reversed). There’s nothing really important about protons having *positive* charge and electrons having negative, other than they are opposites so they attract. There’s no particular reason that if you flipped the charges for every single particle in the universe that you would notice a difference. It’s all *exactly* the same.

And, anything that creates matter also creates an equal amount of antimatter – again, because they’re not special either way. If you smash particles together in the Large Hadron Collider and protons come out, an equal number of antiprotons will also come out with an equal amount of energy between them.

In the earliest fractions of fractions of seconds in the universe, everything was so hot and so dense that it was like the entire universe was like a collider colliding particles at all points everywhere all the time. It was all just energy smashing around. Whatever particles were created *should* have been an equal amount of matter and antimatter.

Why, then, is the universe made almost entirely of what we call normal matter? Where is all the antimatter? If the universe *had* created an equal amount of antimatter, there would be no matter of any sort because it would have all annihilated before the universe could expand and spread stuff apart. You might (very reasonably) wonder if maybe there were just big clumps of one or the other that, sure, annihilated at the boundaries when they touched, but then spread out and now the universe just has big patches of antimatter. In fact, if some distant galaxies were made entirely out of antimatter there would be no difference to see in our telescope…*except*…

Space isn’t *really* empty. There is dust and gas everywhere, even though it’s very very sparse. If huge regions of the universe were made out of antimatter, that dust and gas would inevitably mix and annihilate and give off high-energy light rays, and we would see that. But we *don’t*.

What that all means is that for *some reason*, during the earliest moments of the universe, there was *slightly* more matter than antimatter created and after all the antimatter combined and annihilated with all the normal matter that it could, there was just a teeny tiny bit of regular matter left over. That is all the matter that we see in the universe. That must mean that there is *something* different about normal matter, some property that we haven’t figured out yet, where one or more forces interacts with matter just slightly differently.

Neutrinos are…weird. It’s probably the case that they’re massless particles, but they come in different “flavors” and it’s possible that they spontaneously change “flavor”. One of the flavors may have mass. If so, and if they *do* change, then where does their mass come from? And if neutrinos are their own antiparticle – their own version of antimatter – then as all the neutrinos were annihilating themselves it could explain why the universe ended up with more matter than antimatter.

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