My idea on what happened to all the antimatter.

  • #27
thank you very much arch. that was extremely helpful. Hopefully when I move on in my career (I am only a junior in high school), I can maybe prove or disprove any of these issues. I'll have to keep this idea in the back of my mind. Thanks again!
 
  • #28
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You're welcome, and good luck!
 
  • #29
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hmm...
maybe there is some sort of boson particle such as the higgs boson that altered the properties of most of the existing antimatter and therefore caused the imbalance

just some thought coming out of a highschooler
 
  • #30
Chronos
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The universe has no net charge, for starters. Anti-matter is more hypothesis than fact. There should be tons of it, by some calculations, but there is not. The question is not where it 'went', more like why did we think there was so much of it?
 
  • #32
LURCH
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So far as is known, there is no way for a particle of matter to form without an antimatter particle forming at the same time.

When you say "...Anti-matter is more hypothesis than fact..." exactly what do you mean?
 
  • #33
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I have recently been reading Moment of Creation by James Trefil, and I have stumbled upon the question, where has all the antimatter gone? I asked myself, what if micro black holes produced by the tremendous energy at the big bang are the answer? If you have an understanding in hawking radiation then you know particle-antiparticle pairs are produced at balck holes. What if, by chance, antiparticles were absorbed by these micro black holes more than regular particles. It could explain why there is more matter than antimatter. Has this been dissproved by anyone? Is this a plausible theory?
if there are equal number of matter and antimatter at the beginning then there should be equal chances of micro black holes formed with antimatter too...this is just opposite...so if you say antimatter gone because of micro black holes formed with matter,then matter should also have gone because of micro black holes formed with antimatter...
 
  • #34
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this may be a dumb question, but how do we know there is no antimatter in the univers. By looking at some distant galaxy is there something about it that we can distinguish that it is made of matter rather than antimatter?
 
  • #35
Well we receive many particles from distant galaxies, and none of them turn up to be antiparticles, so it gives us a good indication that they are not made of antimatter.
 
  • #36
Haelfix
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To the OP. In order to have a matter/antimatter asymmetry the necessary and sufficient conditions were layed out by Sakharov in the 60s.

A black hole in and of itself is not sufficient to meet these bounds, however a blackhole and other physics is. So while this isn't exactly what you had in mind, its somewhat related.

For instance Grand unified theories provide a mechanism to have baryon number nonconservation and CP violation. So indeed, if you combine a blackhole with something like that, you presumably satisfy the conditions necessary.

This is whats called blackhole baryogenesis, and it has been looked at before (Hawkings and Zeldovitch were the pioneers afair). The idea being, a blackhole while its radiating under the Hawking process can spit out a bunch of heavy particles, and they in turn can violate lepton or baryon number. The blackhole in that case, acts like a sort of multiplier to the final observed asymmetry.

The problem is, you need a lot of primordial blackholes in the early universe to be of relevance, and this in turn is very sensitive to inflation and is highly model dependant. Moreover Sphaleoron processes damp some of this as well.

You'd probably have to search arxiv for the modern parameter spaces where this hypothesis lives in. I don't know off the top of my head if its been falsified or whether its still active.
 
  • #37
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where is all the antimatter. I was reading up on Fienman diagrams, in an electron / antielectron(positron) interaction, the two particles anihilate and yeild a high energy photon. but that is mathmatically equivilant to an electron absorbing a high energy photon and traveling backwards in time as a positron. So from that argument, an antiparticle is the same as a particle that is traveling back in time. So could the absence of antimatter be a consequence of the one directional nature of time? So to have equal quantities of matter and antimater, time would have to be bidirectional? Seems as reasonable as primordial black holes?
 
  • #38
yea that actually sounds pretty interesting. But we can create anti-particles, so that would break times one-directionality right?
 
  • #39
Vanadium 50
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There are multiple parts to this question. The first question is "is there a global baryon asymmetry (the technical term for the matter-antimatter asymmetry) or are there pockets of matter and pockets of antimatter?" We don't really know the answer to this, but we do know that if there are pockets, they are quite large - perhaps 100 Mpc across. We know this because we don't see evidence of nearby annihilation radiation.

The second question is whether there were enough primordial black holes to force an asymmetry. I don't know for sure, but I suspect that the answer is "no". If the expected asymmetry was due to chance alone, it would mean you'd end up with an excess that is about the size of the square root of the number of PBH's. For example, a 10% matter-antimatter asymmetry would mean ~100 PBH's. A 1% asymmetry would mean ~10,000 PBH's.

The problem is that there's not enough dark matter out there. There is ~8x as much dark matter (including PBH's) as ordinary matter, which would suggest only 64 PBHs. We know that dark matter is very smoothly distributed, and we would need many trillions of them, not just 64. So this doesn't work out well quantitatively.
 
  • #40
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isnt it possible that the antimatter might have got liberated to form something outside the uiniverse and may be it is supporting the universe
 

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