Matter vs Antimatter: Why Does Universe Have More of the Former?

[us40]

Hello,
There is a problem like why universe end up with more matter than anti matter but is it not possible that matter and antimatter does not have enough time to meet and annihilate because of inflationary epoch because of exponential expansion of space time?

 

[dauto]

No, that doesn't work. You wouldn't produce the observed excess that way.

 

[mathman]

Matter-antimatter pairs are created together. They would be all mixed together right after the big bang, so they couldn't separate fast enough.

 

[Chronos]

See http://press.web.cern.ch/backgrounders/matterantimatter-asymmetry for a short explanation. It is considered highly unlikely that large amounts of antimatter survived the big bang.

 

[PAllen]

The annihilation of electrons and positrons produces a characteristic gamma ray energy. Even if matter and antimatter somehow became well separated, we should see many more gamma rays of this characteristic energy than we do if antimatter survived in quantity into the era when the universe became transparent to EM radiation. There are many other lines of evidence as well, but I find this one easy to understand.

 

[Chalnoth]

Hello,
There is a problem like why universe end up with more matter than anti matter but is it not possible that matter and antimatter does not have enough time to meet and annihilate because of inflationary epoch because of exponential expansion of space time?

Close to the end of inflation, there was effectively no matter at all around (or anti-matter). There was only the field that drove inflation. When that decayed, it produced a zoo of particles, with equal numbers of matter and anti-matter particles. How that equal number of matter and anti-matter particles then evolved to the imbalance we see today is the issue at hand.

Anyway, here's the Wikipedia article on the subject:
https://en.wikipedia.org/wiki/Baryogenesis

 

[PAllen]

Close to the end of inflation, there was effectively no matter at all around (or anti-matter). There was only the field that drove inflation. When that decayed, it produced a zoo of particles, with equal numbers of matter and anti-matter particles. How that equal number of matter and anti-matter particles then evolved to the imbalance we see today is the issue at hand.

Anyway, here's the Wikipedia article on the subject:
https://en.wikipedia.org/wiki/Baryogenesis

I thought OP was asking how do we know that there is an imbalance today? If there is no imbalance, there is no problem. That is not immediately obvious, and as recently as circa 1960 there were Nobel winning physicists who weren't convinced we knew there was an imbalance. Today, I don't think there is any serious astrophysicist with any doubt about the imbalance.

 

[Chalnoth]

I thought OP was asking how do we know that there is an imbalance today? If there is no imbalance, there is no problem. That is not immediately obvious, and as recently as circa 1960 there were Nobel winning physicists who weren't convinced we knew there was an imbalance. Today, I don't think there is any serious astrophysicist with any doubt about the imbalance.

Right. But he seemed to be attempting to claim that cosmic inflation would have separated the matter-dominated and anti-matter-dominated regions. This doesn't work for the reasons I mentioned.

 

[Naty1]

In the article linked to by Chronos:

...Researchers have observed particles spontaneously transforming, or oscillating, into their antiparticles at a rate of millions of times per second before decaying. Some unknown entity intervening in this process in the early universe could have caused oscillating particles to decay as matter more often than they decayed as antimatter.

What's the bold face part all about? Never heard about such processes...Edit: Any relation to vacuum energy??

 

[Chronos]

Bear in mind it is believed that only about 1 particle in a billion survived the wild +/- pair annihilation frenzy of the early universe.

 

[PAllen]

This is an interesting question. QFT is not an area I know very well, but I had only heard of neutrino oscillation, not, e.g. muons oscillating to anti-muons millions of times per second. I am definitely interested in the explanation of this statement from someone more knowledgeable in this area. Since the statement is in a CERN public document I assume it has some reasonable justification.

 

[George Jones]

See

http://home.web.cern.ch/about/updates/2013/08/sonata-lhcb-sound-antimatter

http://lhcb-public.web.cern.ch/lhcb-public/

 

[Chalnoth]

This is an interesting question. QFT is not an area I know very well, but I had only heard of neutrino oscillation, not, e.g. muons oscillating to anti-muons millions of times per second. I am definitely interested in the explanation of this statement from someone more knowledgeable in this area. Since the statement is in a CERN public document I assume it has some reasonable justification.

Muons are charged particles. I'm pretty certain that charged particles cannot oscillate into their anti-particles. Neutrally-charged particles, however, can. I believe the earliest-discovered example of this was the $K^0$ meson (aka. the neutral kaon).

 

[PAllen]

Muons are charged particles. I'm pretty certain that charged particles cannot oscillate into their anti-particles. Neutrally-charged particles, however, can. I believe the earliest-discovered example of this was the $K^0$ meson (aka. the neutral kaon).

The misleading thing about the CERN press release referenced early in this thread is that there was was no indication that only some particles oscillate to their anti-particles, and of those, only a few do at the referenced rate of millions of times per second. They went from completely general discussion of antimatter to a specific situation without clarification. The CERN notes that George Jones linked were perfectly clear.

 

[mathman]

The Cern article mentions B⁰ specifically and says there are a few others. Most particles do not oscillate with antiparticles.

 

[PAllen]

The Cern article mentions B⁰ specifically and says there are a few others. Most particles do not oscillate with antiparticles.

Not the first one linked that raised this question:

http://press.web.cern.ch/backgrounders/matterantimatter-asymmetry

 

[Chalnoth]

The misleading thing about the CERN press release referenced early in this thread is that there was was no indication that only some particles oscillate to their anti-particles, and of those, only a few do at the referenced rate of millions of times per second. They went from completely general discussion of antimatter to a specific situation without clarification. The CERN notes that George Jones linked were perfectly clear.

That's really too bad. I didn't look at that press release.

 

[M. Bachmeier]

I'm a novice, but how much of our perceived knowledge of particle / antiparticle annihilation based upon statistical estimation? Statistical inference may apply to our current state, but did it apply to the early development of matter with respect to space and time with respect to expansion of space?

Our we missing something grand? Is there a Rosetta Stone? Are there antiparticles in large quantities within our universe?

 

[Chalnoth]

I'm a novice, but how much of our perceived knowledge of particle / antiparticle annihilation based upon statistical estimation? Statistical inference may apply to our current state, but did it apply to the early development of matter with respect to space and time with respect to expansion of space?

Our we missing something grand? Is there a Rosetta Stone? Are there antiparticles in large quantities within our universe?

Statistics is an application of mathematics. It always applies.

 

[M. Bachmeier]

Would you be surprise if our Maths failed to be the ultimate answer?

I'm sure the Romans felt their methods sound and without question, however, the lack of a zero did make some operations difficult and others impossible.

 

[Chalnoth]

Would you be surprise if our Maths failed to be the ultimate answer?

I'm sure the Romans felt their methods sound and without question, however, the lack of a zero did make some operations difficult and others impossible.

Mathematics is incomplete. But it is proven-correct. It isn't completely certain that our current mathematical models apply to the universe. And there are many mathematical models that we haven't even thought up yet.

But this doesn't mean we've learned nothing. And yes, statistics is absolutely guaranteed to be a part of any "ultimate answer", because it is such a general field of mathematics.

 

[M. Bachmeier]

Don't really have any argument against Maths or statistical estimation, but I've seen statistics being used in highly inappropriate ways.

I realize that small partial interactions being studied have massive numbers of observations, but I get a little uncomfortable when conclusions from a broad set of observations are used to infer the state of a single or small group of events.

Lol. I must be asking for the sun moon and stars to be able to observe limited sets of quanta interaction without the observation affecting the results.

 

[Chalnoth]

Don't really have any argument against Maths or statistical estimation, but I've seen statistics being used in highly inappropriate ways.

Of course. But that doesn't mean statistics is invalid. Nor should it be used to cast aspersions on all uses of statistics.

Discussing how to correctly make use of statistics is a common and essential component of the scientific discourse.