The discussion revolves around the topic of antimatter, particularly its absence in the universe and the asymmetry between matter and antimatter. Participants explore theoretical explanations, historical context, and current understanding related to cosmology, particle physics, and the Big Bang.
Participants express a mix of agreement and disagreement. While there is some consensus on the existence of a slight asymmetry favoring matter, the underlying causes and implications remain contested, with multiple competing views presented throughout the discussion.
Limitations include unresolved questions about the mechanisms behind the observed asymmetry, the role of CP violation, and the conditions of the early universe that led to the current state of matter and antimatter.
Yup. The Wikipedia article on Baryogenesis provides a pretty good overview of the subject.phyzguy said:The current understanding is that there was a slight asymmetry and the universe produced slightly more matter than antimatter. Then after the matter and antimatter annihilated into photons, we were left with photons and matter. Today in the universe there are about 10^9 photons for every baryon, so it is believed that the slight asymmetry was about 1 part in 10^9. However, I believe that the cause for this slight asymmetry, that led to more matter being created than antimatter, is not fully understood.
Tanelorn said:Oldfart are you suggesting negative space and time in anti matter universe creating at the same time as ours? As in Star Trek?
Unfortunately it is something which likely can never be proven so it is just imaginative speculation.
phyzguy said:The current understanding is that there was a slight asymmetry and the universe produced slightly more matter than antimatter. Then after the matter and antimatter annihilated into photons, we were left with photons and matter. Today in the universe there are about 10^9 photons for every baryon, so it is believed that the slight asymmetry was about 1 part in 10^9. However, I believe that the cause for this slight asymmetry, that led to more matter being created than antimatter, is not fully understood.
This doesn't work with what we know about the early universe.cubzar said:My opinion:
Matter and antimatter were created in equal amounts, but gravity caused a slight abundance of matter in some regions of the universe and of antimatter in other regions. Gravity would attract matter to matter, and attract antimatter to antimatter, but repel matter from antimatter, causing matter to clump nearer to other forms of matter. Because gravity is weaker than the other forces, it would only create a small asymmetry.
cubzar said:My opinion:
Matter and antimatter were created in equal amounts, but gravity caused a slight abundance of matter in some regions of the universe and of antimatter in other regions. Gravity would attract matter to matter, and attract antimatter to antimatter, but repel matter from antimatter, causing matter to clump nearer to other forms of matter. Because gravity is weaker than the other forces, it would only create a small asymmetry.
At the end of inflation, matter and anti-matter were produced in equal quantities. Later, CP violation effects caused the amount of matter to ever so slightly exceed the amount of anti-matter, resulting in some amount of matter left over once all of the anti-matter had annihilated.Tanelorn said:Was any anti matter created at all during the big bang and inflation era?
Not atoms, no. At the time most of the annihilation was going on, our universe was a quark-gluon plasma, without even any identifiable protons or neutrons, let alone atoms. As the temperature fell, protons and neutrons condensed out of this quark-gluon plasma.Tanelorn said:Are we talking about an almost equal amount of anti protons, neutrons, hydrogen, and helium that was annihilated into energy and then back to matter/anti matter again many times until the last of the anti matter dissappeared from the universe?
Chalnoth said:At the end of inflation, matter and anti-matter were produced in equal quantities. Later, CP violation effects caused the amount of matter to ever so slightly exceed the amount of anti-matter, resulting in some amount of matter left over once all of the anti-matter had annihilated.
Not atoms, no. At the time most of the annihilation was going on, our universe was a quark-gluon plasma, without even any identifiable protons or neutrons, let alone atoms. As the temperature fell, protons and neutrons condensed out of this quark-gluon plasma.
Well, we have seen some. The degree of CP violation that we have seen so far doesn't explain the matter/anti-matter asymmetry, but the fact that we have seen some makes this a very strong candidate for explaining the matter/anti-matter asymmetry.Nicodemus said:Still need that CP violation in the lab though...
Chalnoth said:Well, we have seen some. The degree of CP violation that we have seen so far doesn't explain the matter/anti-matter asymmetry, but the fact that we have seen some makes this a very strong candidate for explaining the matter/anti-matter asymmetry.
The CP Violation Wikipedia article is pretty good for what we know about this so far:Nicodemus said:I didn't know that, and all I have to say is: cool. I do want to say, I wasn't casting aspersions on the theory, I just noted that the LHC crowd is waiting for something more, and this is one of those "mores". I gather it would be right up there with anything that has "Higgs" in the name.