Matter/antimatter imbalenc - forked from AMA ask a physicist

[Scott DeWar]

@Freyer, @Umbran, all the others who know their 'stuff', I will start with the last quote from the ama in the s block below:

[sblock=quote]

Umbran does a pretty good job breaking down the logical possibilities. I'd like to elaborate, though, especially because that wikipedia article is a bit disappointing compared to most of the physics wikipedia articles.

The most important point to remember is that we really don't know the answer to this question. It's also quite likely we won't for a long time, since there's very little way to test any of the possibilities --- there are some potentially related effects we can test experimentally, but those are really only good at ruling out options as opposed to pointing toward the correctness of one.

---

This is what people think happens for the most part (I'll explain why below), though how this happens is completely up in the air. What we do know is that there are several criteria that have to be met (called the Sakharov conditions) and that they are not satisfied (enough) by the Standard Model of particle physics. In fact, the Standard Model can almost cause a predominance of matter over antimatter, but it would require a certain behavior of the Higgs boson field in the early universe --- and in the Standard Model, the Higgs doesn't behave that way. To get it to work, you have to add other ingredients to change the behavior of the Higgs.

Of course, there are other possibilities. There could be an entirely new, undiscovered group of particles that are responsible for the excess of our matter. The roots of the excess could happen during inflation. Or another possibility is that dark matter is also somehow unbalanced between matter and antimatter, and that imbalance gets generated at the same time as the imbalance of normal matter. There are many different theories.

I should also mention that the excess amount of matter is very tiny. In the early universe, the amount of matter and antimatter was essentially equal. For roughly every 10 billion matter/antimatter pairs of particles, there was one extra matter particle. Then all the 10 billion or so pairs annihilated each other away, leaving behind the one matter particle.

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There's a way this is correct and a way it's not correct, so I want to be very careful here.

If we're talking about the decay rates of "everyday" particles and their antiparticles (like protons/antiprotons, neutrons/antineutrons, and electrons/positrons), this is a logical possibility that just doesn't work out. Based on cosmic ray measurements, the lifetime of the antiproton is at least a million years, which wouldn't leave enough of an imbalance between protons/antiprotons. Furthermore, there's a mathematical theorem in particle physics that says the total decay rates of particles and their antiparticles must be the same, and any decay of a proton/antiproton generates the same amount of matter/antimatter. It doesn't work (incidentally, a violation of this theorem would be a super-big deal, meaning we'd have to redo basically all of subatomic physics).

On the other hand, it is possible that some very heavy undiscovered particle and antiparticle decay differently into matter and antimatter. That can happen and can create the imbalance we need. Of course, we've not discovered such a particle yet.*[1]

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This is an interesting idea, though I confess I've not seen any work related to it. I also can't immediately think of a way to implement it, either, since, if it's just a "local" fluctuation, it would have to be created during inflation. Anyway, suffice it to say that I'm not sure if there's a way to get this to work off the top of my head*[2b].

[/sblock]

1st, let me be clear that I understand that Wikipedia is never wrong can be rife with inaccuracies;
2nd, I understand that,as you have both mentioned, too little is understood, knowen and untestable AT THIS TIME AND DATE.

The CPT Theorem guarantees that a particle and its antiparticle have exactly the same mass and lifetime*[1],
and exactly opposite charge. Given this symmetry, it is puzzling that the universe does not have equal amounts of matter and antimatter. Indeed, there is no experimental evidence that there are any significant concentrations of antimatter in the observable universe. There are two main interpretations for this disparity: either the universe began with a small preference for matter (total baryonic number of the universe different from zero), or the universe was originally perfectly symmetric, but somehow a set of phenomena contributed to a small imbalance in favour of matter over time. The second point of view is preferred, although there is no clear experimental evidence indicating either of them to be the correct one.

*[1] as it is posited that the lifetime is exactly the same for particle and anti particle, what is the possibility, not necessarily the probability, that there may be pockets of anti-matter in the universe in the dark corners that have not met up with its counter part? held in vacuum it is safely kept away, having been thrust away by the hot bang?

[2] are there expiraments in the science community working on discovering a way to test/find antimatter?
[2a] who is doing this?
[*[2b] I see you had answered that question. Sorry.

I have so very fallen in a pit of 'out of my depth here, so, ignore the links below. I had questions, But I can't get them to be printed.

Here is my last question here:

[3]Is it possible, but not necessarily probable, that the anti-matter may be what is fueling the black holes?
[3a] Any thoughts on how to approach a way to test this idea?

Please note I labeled that as only an idea, and nowhere near a theory.

[sblock=references]

I hope I have given proper credit here:

1. Wikipedia - Baryogeneisis

2. Dirac equatioin

3. CPT Symetrey

4. PDF on Sakharov Conditions for Baryogenesis ByDennis V. Perepelitsa,Columbia University Department of Physics;(Dated: November 25, 2008)

[/sblock]

More to come . . . . having some bad connectivity issues here, so this will be slow going . . . .Never mind. My brain is itching too much.

 

[tomBitonti]

I should also mention that the excess amount of matter is very tiny. In the early universe, the amount of matter and antimatter was essentially equal. For roughly every 10 billion matter/antimatter pairs of particles, there was one extra matter particle. Then all the 10 billion or so pairs annihilated each other away, leaving behind the one matter particle.

So many quotes ... I've left off the attribute of the above.

I've always wondered ... if so much matter/antimatter combined, wouldn't that create a huge excess of energy? Where is that 10^10 factor of energy?

That is, particle/antiparticle annihilation doesn't destroy the energy of the particles. Depending on the energy of the particles, very roughly speaking, either, a photon is produced, or a photon and some other particles are produced, or maybe just some new particles depending on the exact energy of the event.

Or does the energy recycle back into particles, but, considering the whole cycle, inefficiently, leaving a growing excess of matter?

But then, the fraction seems too high! There would be so many creation/annihilation events in the early universe, one in 10 billion seems to to be too many.

Or do the events only happen in some narrow transition region, say, when matter and light decoupled? Or very very early, such that the relevant time where the asymmetry mattered was very short?

Thx!

TomB

 

[Umbran]

*[1] as it is posited that the lifetime is exactly the same for particle and anti particle, what is the possibility, not necessarily the probability, that there may be pockets of anti-matter in the universe in the dark corners that have not met up with its counter part? held in vacuum it is safely kept away, having been thrust away by the hot bang?

The issue there is that there's no reason for it to have been "thrust away". We would have expected the matter and antimatter to have been created in a homogeneous spread - where every matter particle created had its antimatter counterpart right next to it. It'd be like having an incredibly large and dense bag of mixed vegetables, and finding somehow all the diced carrots spontaneously migrated to one corner of the bag.

[2] are there expiraments in the science community working on discovering a way to test/find antimatter?

Like anything else, you'd notice antimatter by its interactions. Now, its interactions with other antimatter would look exactly like matter interactions with matter. So, you can have a star of anti-hydrogen fusing away to anti-helium, and emitting light, and you'd be none the wiser - it'd just look like a star from far away. You could have a whole galaxy of antimatter stars, and from a distance it would look normal...

...Except where it met a boundary with normal matter. Then things go kablooey. If there were large areas of antimatter within the visible universe, you'd expect to find boundaries between that and the region(s) with normal matter - at those boundaries, matter meets anti-matter, annihilates, and produces X-rays (If I recall the energies correctly - gamma rays if not X-rays).

There are, and have been, several X-ray telescopes. I don't know if any have surveyed for precisely this effect, but a couple of previous telescopes did do full sky surveys. I think they've looked at enough of the sky that they'd have seen it if it was there. This suggest that there are no such regions in the visible universe.

This is where the hypothesis I mentioned in the other thread comes in. It posits that, after the big bang, the only regions that fell out of inflation were regions that, for whatever reason (including just statistical variation), just happened to have at least a slight predominance of either matter or antimatter. So, there's a multiverse of bubbles, separated by the vast inflating deeps, that are dominated by one or the other. The next universe over may be an antimatter universe.

And this fits nicely into the anthropic principle Freyar mentioned. We live in the universe we do, because if it wasn't this way, it wouldn't be livable, or even exist. If we were in a region that had even distribution of matter and anti-matter, it'd never have stopped inflating.

 

[Janx]

Some extra Questions:

a) How do we know Anti-matter exists?
Is it possible we've made some stuff up because of our human love of symmetry?
This is likely explainable by Umbran, but it seems like a ground floor assumption to confirm.

b) what if the big bang was the collision of matter + anti-matter in an uneven mix? All that energy went somewhere, our universe being the result.


c) what is anti-matter made of and how is that different from normal matter (ex. protons, electrons, neutrons are made of things)?

d)Does Anti-Matter really matter?

 

[Scott DeWar]

The issue there is that there's no reason for it to have been "thrust away". We would have expected the matter and antimatter to have been created in a homogeneous spread - where every matter particle created had its antimatter counterpart right next to it. It'd be like having an incredibly large and dense bag of mixed vegetables, and finding somehow all the diced carrots spontaneously migrated to one corner of the bag.

what is the possibility of being wrong on this? I know I have read that the mass is the same, but what if we are wrong on thiss too? If we are incorrect, we would be looking at the possibility of a "Brazil nut effect" (how the largest nuts float to the top of the can)

Like anything else, you'd notice antimatter by its interactions. Now, its interactions with other antimatter would look exactly like matter interactions with matter. So, you can have a star of anti-hydrogen fusing away to anti-helium, and emitting light, and you'd be none the wiser - it'd just look like a star from far away. You could have a whole galaxy of antimatter stars, and from a distance it would look normal...

Did I read somewhere that anti-matter spins in the opposite direction or some such as that?

...Except where it met a boundary with normal matter. Then things go kablooey. If there were large areas of antimatter within the visible universe, you'd expect to find boundaries between that and the region(s) with normal matter - at those boundaries, matter meets anti-matter, annihilates, and produces X-rays (If I recall the energies correctly - gamma rays if not X-rays).

I definitely understand this.

There are, and have been, several X-ray telescopes. I don't know if any have surveyed for precisely this effect, but a couple of previous telescopes did do full sky surveys. I think they've looked at enough of the sky that they'd have seen it if it was there. This suggest that there are no such regions in the visible universe.

I humbly point out: Our visible and known universe

This is where the hypothesis I mentioned in the other thread comes in. It posits that, after the big bang, the only regions that fell out of inflation were regions that, for whatever reason (including just statistical variation), just happened to have at least a slight predominance of either matter or antimatter. So, there's a multiverse of bubbles, separated by the vast inflating deeps, that are dominated by one or the other. The next universe over may be an antimatter universe.

And this fits nicely into the anthropic principle Freyar mentioned. We live in the universe we do, because if it wasn't this way, it wouldn't be livable, or even exist. If we were in a region that had even distribution of matter and anti-matter, it'd never have stopped inflating.

I now have to admit, I am getting mentally exhausted. Yes, once again: Results of the coma. I am sure I read what you pointed out. I am now haveing absortion problems complicated by a wonky internet connection. I just hope I don't lose what I have on this post.

 

[Morrus]

Some extra Questions:

a) How do we know Anti-matter exists?
Is it possible we've made some stuff up because of our human love of symmetry?
This is likely explainable by Umbran, but it seems like a ground floor assumption to confirm.

We've seen it; and not just in space - on Earth, too. Cosmic rays hitting the atmosphere produces it, some radioactive decay produces it, we've even created it in very small quantities. We even use it in some high end medical imaging procedures.

 

[Scott DeWar]

Some extra Questions:
d)Does Anti-Matter really matter?

I just had a friend jokingly ask that question

 

[Scott DeWar]

We've seen it; and not just in space - on Earth, too. Cosmic rays hitting the atmosphere produces it, some radioactive decay produces it, we've even created it in very small quantities. We even use it in some high end medical imaging procedures.

So there is an existing and verifiable test to prove the existance of ant-matter.

I will look up more on this. for the high end medical test equipment, what would that be?

 

[tomBitonti]

Some extra Questions:
a) How do we know Anti-matter exists?

Anti-matter has been fabricated in laboratories, including not just particle/anti-particle pairs, but also whole anti-hydrogen molecules.

https://en.wikipedia.org/wiki/Pair_production

And:

https://en.wikipedia.org/wiki/Antihydrogen

At least the Positron occurs naturally, just not in large and durable quantities:

https://en.wikipedia.org/wiki/Positron

Actually, there are large quantities of anti-matter out there, but it is accountable for (kindof) as being generated by black holes:

http://www.dailygalaxy.com/my_weblog/2010/10/do-black-holes-eject-antimatter-.html

But on a cosmological scale, this is a tiny amount, and it won't last for long. The cloud of positrons of the immediately preceding reference is gradually being destroyed (with, according to the article, the energy output of 11,000 stars!)

Thx!
TomB

 

[Scott DeWar]

Anti-matter has been fabricated in laboratories . . . . .lots of good stuff . . . . . .. The cloud of positrons of the immediately preceding reference is gradually being destroyed (with, according to the article, the energy output of 11,000 stars!)

Thx!
TomB

I found this link[urlhttp://www.freepatentsonline.com/EP0050596.html=] FPO ip research & communities[/url] in a link on the "Procedure for transforming electrical energy to anti-matter with positron storage"

They have at the very opening:

The positrons produced between the plates are then separated from the electrons with suitable magnetic fields and carried to suitable magnetic containers with magnetic guides, using mirror, toroidal or other type of magnetic field. The electrons produced are carried with a suitable magnetic guide to be used as a source for the accelerator beam in the procedure.

Just a thought: What if there was some super-magnetic force that separated the anti-matter from the matter to create the pockets of the anti-matter. Maybe this is the source of the development of the anti-matter universes previously mentioned?

And furthermore you need to keep the universes separated or . . . . .Kaboom!

https://www.youtube.com/watch?v=XN32lLUOBzQ