According to the Standard Model of our universe, beginning with the Big Bang, there is no difference between matter and antimatter (although they annihilate each other on contact). Why then do we see all matter, no antimatter? A group of physicists decided to test a new theory: From ScienceDaily:
About ten picoseconds after the Big Bang — right about the time the Higgs boson was turning on — the universe was a hot plasma of particles.
“The technique of dimensional reduction lets us replace the theory which describes this hot plasma with a simpler quantum theory with a set of rules that all the particles must follow,” explains Dr. David Weir, the corresponding author of the article.
“It turns out that the heavier, slower-moving particles don’t matter very much when these new rules are imposed, so we end up with a much less complicated theory.”
This theory can then be studied with computer simulations, which provide a clear picture of what happened. In particular, they can tell us how violently out of equilibrium the universe was when the Higgs boson turned on. This is important for determining whether there was scope for producing the matter-antimatter asymmetry at this time in the history of the universe using the Two Higgs Doublet Model.
“Our results showed that it is indeed possible to explain the absence of antimatter and remain in agreement with existing observations,” Dr. Weir remarks. Importantly, by making use of dimensional reduction, the new approach was completely independent of any previous work in this model.
If the Higgs boson turned on in such a violent way, it would have left echoes. As the bubbles of the new phase of the universe nucleated, much like clouds, and expanded until the universe was like an overcast sky, the collisions between the bubbles would have produced lots of gravitational waves. Researchers at the University of Helsinki and elsewhere are now gearing up to look for these gravitational waves at missions such as the European LISA project. Paper. (open access) – Jens O. Andersen, Tyler Gorda, Andreas Helset, Lauri Niemi, Tuomas V. I. Tenkanen, Anders Tranberg, Aleksi Vuorinen, David J. Weir. Nonperturbative Analysis of the Electroweak Phase Transition in the Two Higgs Doublet Model. Physical Review Letters, 2018; 121 (19) DOI: 10.1103/PhysRevLett.121.191802 More.
Well, we shall see! This feels so much more like science than hearing someone merely make a claim that there must be another universe out there that is all antimatter.
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See also: Clue about antimatter: Does it depend on how neutrinos behave vs. antineutrinos?
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