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The article says this could explain "why matter won out over antimatter in the early universe." Can someone explain that to me? > If neutrinos are their own an
by snewman 11y ago
The article says this could explain "why matter won out over antimatter in the early universe." Can someone explain that to me?
> If neutrinos are their own antiparticles, it’s possible that the antineutrinos emitted during double beta decay could annihilate one another and disappear, violating lepton number conservation. This is called neutrinoless double beta decay.
> Such a process would favor matter over antimatter, creating an imbalance.
If the initial universe contained equal amounts of matter and antimatter, wouldn't there also have been "anti double beta decay"? (Where an antimatter nucleus decays into a different anti-nucleus and emits two positrons and two neutrinos; and then the two neutrinos could annihilate one another and disappear.) They haven't explained where the asymmetry comes in.
- dukwon 11y agoCP violation. The rates of some weak-force processes are measurably different when you replace particles with their antiparticles. This has been observed in processes involving quarks for over 50 years now. We haven't quite done it with leptons yet because of the difficulties involved in detecting neutrinos. See also the Sakharov conditions for baryogenesis
- andrewflnr 11y agoAll this time I thought it was a big mystery why there's more matter than anti-matter, but now you're telling me we've known this whole time that the rules were different between them? All we're waiting for is to find out what specific processes made it work out? I've always gotten this breathless "how could it be?" impression when people talk about that issue.
- philipov 11y agoTo be fair, that's a pretty common reaction to most of advanced physics.
- dukwon 11y agoCP violation is a necessary component, but it doesn't completely explain the whole matter-antimatter asymmetry. We still haven't ever observed a process that doesn't conserve baryon or lepton numbers, which is another crucial component.