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Author Topic: Did matter and anti-matter meet in the early Universe?  (Read 16735 times)

Offline barneyboy

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Hi what percentage of the newly formed universe was left after matter and anti mater combined? is there any "proof" that it annihilates each other.
« Last Edit: 28/01/2015 09:01:05 by chris »


 

Offline yor_on

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Re: matter/anti matter
« Reply #1 on: 02/01/2015 18:00:47 »
List of unsolved problems in physics

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

So, go for it.
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #2 on: 02/01/2015 19:46:12 »
Hi what percentage of the newly formed universe was left after matter and anti matter combined?
50%

Is there any "proof" that it annihilates each other.
Yes, annihilation. But there's a wrinkle, and it's a Lulu. See this article? It's about positronium. Positronium is a short-lived "exotic atom". It isn't matter, or antimatter, it's both. OK? Now read this carefully:

"The Positronium (Ps) atom consists of an electron and a positron orbiting their mutual center of mass. To a first approximation it can be regarded as a sort of light hydrogen atom."

Positronium can be regarded a sort of light hydrogen. What does that suggest to you? You know what it suggests to me? That the electron is matter, and the proton is antimatter. People normally say the proton is matter and the antiproton is antimatter. But why? It's pure convention, nothing else. IMHO the  "mystery of the missing antimatter" is like saying the men won the tennis match. Even though it was mixed doubles.     
 

Offline evan_au

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Re: matter/anti matter
« Reply #3 on: 03/01/2015 19:56:19 »
Quote from: JohnDuffield
Quote
what percentage of the newly formed universe was left after matter and anti matter combined?

50%

I am interested in where the 50% comes from?
 
Is this estimated from the observed ratio of matter to light in the universe, or some other source?
 

Offline evan_au

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Re: matter/anti matter
« Reply #4 on: 03/01/2015 20:16:07 »
Quote
People normally say the proton is matter and the antiproton is antimatter. But why? It's pure convention, nothing else.

I agree that the definition of matter & antimatter is purely convention.
As I understand it, the convention is this:
  • "Matter" is that fairly stable stuff we see around us, that has been studied for centuries by chemists and alchemists.
  • "Anti-matter" is very unstable stuff that was predicted by physicists in the 20th century, and then finally discovered in high-energy nuclear collisions. It rapidly annihilates when it comes in contact with all that matter which the chemists have been studying for so long.

Since the Hydrogen we see throughout our galaxy is stable on human timescales, and composed of a proton and an electron, I must conclude from this convention that the proton and the electron and proton are both "matter".

The antiproton has a negative charge (like the electron). This universe would be most uncomfortable for creatures like us if the universe were composed of electrons and anti-protons (or positrons and protons). None of the familiar atoms or molecules could form.
 

Offline lightarrow

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Re: matter/anti matter
« Reply #5 on: 03/01/2015 23:47:36 »
As I understand it, the convention is this:
  • "Matter" is that fairly stable stuff we see around us,
    "Anti-matter" is very unstable stuff that
 
?
Antimatter is as stable as matter, according to our present knowledge.

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« Last Edit: 03/01/2015 23:50:11 by lightarrow »
 

Offline barneyboy

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Re: matter/anti matter
« Reply #6 on: 21/01/2015 23:47:20 »
if matter and antimatter combine, what becomes of the energy's of the combined? and what becomes of the mass of the recently combined component's.
 

Offline Ethos_

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Re: matter/anti matter
« Reply #7 on: 22/01/2015 00:20:54 »
Quote from: JohnDuffield
Quote
what percentage of the newly formed universe was left after matter and anti matter combined?

50%

I am interested in where the 50% comes from?
 


I would also be interested in that data. I seem to remember reading somewhere that that percentage was much smaller than 50%. I have tried to find verification on that figure but have not yet been successful. If anyone can find credible information about this, please post it for our edification.
 

Offline Ethos_

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Re: matter/anti matter
« Reply #8 on: 22/01/2015 00:33:47 »
From my investigation, it seems that shortly after the big bang, for every 10 billion particles of antimatter, there were 10 billion plus one of matter created. After annihilation takes place between antimatter and matter, that would only leave one particle in 20 billion left.

This works out to about: .0000000002%
« Last Edit: 24/01/2015 22:07:52 by Ethos_ »
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #9 on: 22/01/2015 13:40:34 »
Sorry evan, I didn't see your post. I shall offer my belated reply:

I am interested in where the 50% comes from? Is this estimated from the observed ratio of matter to light in the universe, or some other source?
The latter. Put simply: in pair production in the early universe we produced electrons and positrons and protons and antiprotons. We now have baryon asymmetry and lepton asymmetry wherein only two out of the original four survive. That's 50%.   

I agree that the definition of matter & antimatter is purely convention. As I understand it, the convention is this:
  • "Matter" is that fairly stable stuff we see around us, that has been studied for centuries by chemists and alchemists.
  • "Anti-matter" is very unstable stuff that was predicted by physicists in the 20th century, and then finally discovered in high-energy nuclear collisions. It rapidly annihilates when it comes in contact with all that matter which the chemists have been studying for so long.

Since the Hydrogen we see throughout our galaxy is stable on human timescales, and composed of a proton and an electron, I must conclude from this convention that the proton and the electron and proton are both "matter".
There's an ambiguity here. On the one hand individual particles are labelled as matter and antimatter. On the other hand combinations of particles are labelled as matter and antimatter. The result of that is the mystery of the missing antimatter. It's a bit like watching a game of mixed-doubles tennis, then declaring that the men won, then musing about the mystery of the missing women. By hook or by crook, regardless of how evenly matched they were, one side was always going to win, and then we would call it matter. IMHO the situation is somewhat similar to enantiomers. We don't ponder the mystery of the missing L-glucose.   

The antiproton has a negative charge (like the electron). This universe would be most uncomfortable for creatures like us if the universe were composed of electrons and anti-protons (or positrons and protons). None of the familiar atoms or molecules could form.
But if it was composed of antiprotons and positrons, all of the familiar atoms and molecules would form. And we would still have called it matter!
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #10 on: 22/01/2015 13:52:52 »
I would also be interested in that data. I seem to remember reading somewhere that that percentage was much smaller than 50%. I have tried to find verification on that figure but have not yet been successful. If anyone can find credible information about this, please post it for our edification.
See above. The thing to remember is that the matter and antimatter was formed from pair production. Imagine that four zillion matter and antimatter particles were created over some period, during which time were also being destroyed by annihilation and by "melting" in a quark-gluon plasma. Now only two zillion survive. 

From my investigation, it seems that shortly after the big bang, for every 10 billion particles of antimatter, there were 10 billion plus one of matter created.
Don't forget that the particles were created via pair production. If 10 billion particles of antimatter were created, 10 billion particles of matter were created.

After annihilation takes place between antimatter and matter, that would only leave one particle in 10 billion left. This works out to about: .0000000001%
The trick is to destroy more of one than the other. Have a look at melting particles in a quark-gluon plasma. If by chance you melt more of one type than the other, you get into a "stability tip" where the more common type gets more common. 
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #11 on: 24/01/2015 16:33:30 »
Anyway, if anybody asks me about the mystery of the missing antimatter, I say what mystery? Then when they say where has all the antimatter gone? I say this:

It hasn't gone anywhere. Weight by weight, you are 99.95% made of it.


 

Offline chiralSPO

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Re: matter/anti matter
« Reply #12 on: 24/01/2015 18:11:40 »
Anyway, if anybody asks me about the mystery of the missing antimatter, I say what mystery? Then when they say where has all the antimatter gone? I say this:

It hasn't gone anywhere. Weight by weight, you are 99.95% made of it.

ok, then. where has all the matter gone?

This isn't an issue of matter vs antimatter, which, as you have pointed out, is just a matter (no pun intended) of definition. The issue is parity: for each particle that we observe, where is the corresponding antiparticle?
 

Offline syhprum

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Re: matter/anti matter
« Reply #13 on: 24/01/2015 20:04:47 »
If in the early universe a vast amount of matter/antimatter annihilation occurred what has happened to all the resulting gamma radiation produced, has it degraded into the CMBR ?
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #14 on: 25/01/2015 13:30:35 »
ok, then. where has all the matter gone? This isn't an issue of matter vs antimatter, which, as you have pointed out, is just a matter (no pun intended) of definition. The issue is parity: for each particle that we observe, where is the corresponding antiparticle?
It got melted. The early universe was a "maelstrom" of pair-production and annihilation. But if that's all you've got, you have to end up with the same number of electrons and positrons, and the same number of antiprotons and protons. You also have something akin to a "quark-gluon plasma" where you can melt particles and so destroy them without using an antiparticle. See this article. Note though that a quark-gluon plasma is something like pea soup: there are no actual peas in pea soup.

If in the early universe a vast amount of matter/antimatter annihilation occurred what has happened to all the resulting gamma radiation produced, has it degraded into the CMBR?
Some of the gamma radiation will have been recycled to make more matter. Maybe some became the CMBR, but that dates to something like 350,000 years after the big bang. AFAIK the pair production etc was before that.
« Last Edit: 25/01/2015 13:34:42 by JohnDuffield »
 

Offline chiralSPO

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Re: matter/anti matter
« Reply #15 on: 25/01/2015 15:24:28 »
Thanks for the link about "melting." I still have some questions about this answer, though:

But by "melting" the hadrons into quark-gluon soup, they are not destroyed--it's just  phase transition. Wouldn't they coalesce again into hadrons when it gets cold enough? Also it doesn't solve the matter-antimatter dilemma because protons break down into quarks and antiprotons break down into antiquarks... As far as I know quarks and antiquarks do not interconvert.

"Melting" also does not appear to have anything to do with leptons (electrons and positrons), so even if this solves the problem for hadrons, we still have a problem with leptons. No?


 

Online jeffreyH

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Re: matter/anti matter
« Reply #16 on: 25/01/2015 18:02:28 »
John may have a point here.

http://en.wikipedia.org/wiki/Flavour_(particle_physics)
"Elementary particles are not eternal and indestructible. Unlike in classical mechanics, where forces only change a particle's momentum, the weak force can alter the essence of a particle, even an elementary particle. This means that it can convert one quark to another quark with different mass and electric charge, and the same for leptons. From the point of view of quantum mechanics, changing the flavour of a particle by the weak force is no different in principle from changing its spin by electromagnetic interaction, and should be described with quantum numbers as well. In particular, flavour states may undergo quantum superposition."

It all depends upon when the weak force became a separate entity. Quark modification could be the process by which an imbalance occurred. This cannot be verified by experiment however IMO.
« Last Edit: 25/01/2015 18:04:21 by jeffreyH »
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #17 on: 25/01/2015 22:00:33 »
But by "melting" the hadrons into quark-gluon soup, they are not destroyed--it's just  phase transition. Wouldn't they coalesce again into hadrons when it gets cold enough? Also it doesn't solve the matter-antimatter dilemma because protons break down into quarks and antiprotons break down into antiquarks... As far as I know quarks and antiquarks do not interconvert.
No, they melt. They are totally destroyed. There are no peas in pea soup, there are no quarks in a quark-gluon plasma. Note that gluons in ordinary hadrons are virtual. They aren't real. So there's no gluons in a quark-gluon plasma either.  It's just this rather odd state of matter / energy. I think of it as something like one big high-pressure photon going nowhere. Don't forget that we can perform low-energy proton-antiproton annihilation to gamma photons. The cross section is something like 1%. The quarks and antiquarks are totally destroyed there too.


Image credit CSIRO, see http://www.atnf.csiro.au/outreach/education/senior/cosmicengine/bigbang.html


"Melting" also does not appear to have anything to do with leptons (electrons and positrons), so even if this solve the problem for hadrons, we still have a problem with leptons. No?
No. If you can destroy a proton you can destroy an electron.
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #18 on: 25/01/2015 22:17:25 »
John may have a point here... the weak force can alter the essence of a particle, even an elementary particle...
Yep. I've talked to people about trick ways to get round conservation of charge. I think conservation of energy and conservation of momentum do hold, but charge is intimately related to electron spin. If you could contrive things such that an electron emitted two orthogonal photons, you'd be left with a photon. I don't think there's any way to do this in practice, but the general idea is something like this
 

Offline lightarrow

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Re: matter/anti matter
« Reply #19 on: 25/01/2015 22:28:20 »
Anyway, if anybody asks me about the mystery of the missing antimatter, I say what mystery? Then when they say where has all the antimatter gone? I say this:
It hasn't gone anywhere. Weight by weight, you are 99.95% made of it.
Ah! So the other 0.05% of me is made of Holy Spirit, isnt'it?

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Offline JohnDuffield

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Re: matter/anti matter
« Reply #20 on: 25/01/2015 23:10:02 »
No. Matter.
 

Online jeffreyH

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Re: matter/anti matter
« Reply #21 on: 25/01/2015 23:40:11 »
No. Matter.

You were starting to impress me and now you've blown it again.
 

Offline Ethos_

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Re: matter/anti matter
« Reply #22 on: 26/01/2015 17:13:03 »
No. Matter.

You were starting to impress me and now you've blown it again.
I concur.........................
 

Offline Ethos_

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Re: matter/anti matter
« Reply #23 on: 26/01/2015 17:17:28 »
No. Matter.
This belongs in the New Theories Section.
 

Offline JohnDuffield

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Re: matter/anti matter
« Reply #24 on: 26/01/2015 17:32:57 »
No it doesn't. What belongs in the trashcan is the definition of matter and antimatter as both individual particles and combinations of particles. What doesn't, is knowing that positronium is an exotic atom that's made up of both matter and antimatter. And that to a first approximation it can be regarded as a sort of light hydrogen atom.
 

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Re: matter/anti matter
« Reply #24 on: 26/01/2015 17:32:57 »

 

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