Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why there's more matter than anti-matter?

  1. Oct 1, 2009 #1


    User Avatar
    Gold Member

    What kind of theoretical explanations are there?

    And can we prove any of them?

    I mean this asymmetry is like the asymmetry in humans who write in their right hand rather than their left hand (I think that statistically there are more right hand writers), I don't think there's an explanation why most of us write in our right hand, or am I wrong in this assumption?
  2. jcsd
  3. Oct 1, 2009 #2
    Maybe because there is no C-invariance?
    Last edited: Oct 1, 2009
  4. Oct 1, 2009 #3


    User Avatar
    Science Advisor

    There is a theorem by Sakharov on this subject. You need at least three necessary conditions to be true in order for a universe to generate more matter than antimatter

    1) CP violation.
    2) Baryon number violation
    3) Departures from thermal equilibrium.

    We know that nature has cp violation, and we know that the third condition holds true based on current cosmological models.

    The second condition is the hard one. Currently the standard model of physics, at least perturbatively conserves B so in order to explain the asymmetry a theory beyond the standard model is required.
  5. Oct 1, 2009 #4
    I would add

    0) "Asymmetric" initial conditions,
    4) Incrementing fluctuations (instabilities) in a non-equilibrium high energy medium.
    Last edited: Oct 1, 2009
  6. Oct 1, 2009 #5
    Actually, baryon number violation is the only Sakharov condition that the standard model can provide sufficiently. It does so through non-perturbative gauge configuration called Sphaelerons, which change B+L while conserving B-L.

    While the standard model has CP violation, it doesn't have enough CP violation to create a baryon asymmetry as large as the universe actually has. And, standard model cosmology can't get far enough out of thermal equilibrium to create the asymmetry.
  7. Oct 2, 2009 #6
    When I was in primary school students were scolded if they swapped hands when writing; they were forced to pick a hand and stick with it. Right hands were encouraged. I've always wondered what that was about. Is this practise still enforced?
  8. Oct 2, 2009 #7


    User Avatar
    Science Advisor

    Neither Sphaeleron production or the amount of CP violation is sufficient (well at least without positing extra structure) to generate the observed asymmetry. Sphaeleron production is ridiculously tiny, and the accidental symmetry of the standard model holds to a very high degree.

    The actual numbers are dependent on a bunch of things, like cosmological parameters. In general, in Baryogenesis models you try to enhance both the B as well as CP violation substantially with GUT and thermal processes and that almost fits (actually you probably need a leptogenesis phase as well). There is a certain amount of model building freedom where you trade off between the quantities of the 3 conditions.
  9. Oct 2, 2009 #8
    That's a good interesting answer, Haelfix, thanks! "Sphaleron" launched me into all kinds of interesting wiki-pages!

    I'm wondering if heavy elements in the earth (uranium etc) are forged, not in our sun (too small), but in some much more massive/more ancient supernova explosion... I'm wondering why "Big Bang Theory" claims that the "Big Bang" only produced hydrogen and a bit of helium (maybe one or two random complex molecules)?

    Surely, the "Big Bang", the very FONT of pure energy from which this cosmos is manufactured, would have been much more capable of creating heavier elements than mere insignificant SUPERNOVA fission/fusion explosions. Surely the "Big Bang" is the most explosive/high-energy phenomenon in existence, in which case ALL the elements would have formed right at the start!

    Antimatter, however... Well when you look at Feynman diagrams you see the particle and its anti-particle bouncing away in opposite directions. In other words, if there IS an equal-quantity antimatter universe parallel to ours "out there", there must be some distance/dimension keeping us apart otherwise there would be fiery cosmic holocaust everywhere.
  10. Oct 2, 2009 #9


    User Avatar
    Gold Member


    "Left-handedness is still strongly discouraged in some cultures. In the Maswai culture in Africa, "almost 90 percent of teachers and parents said that if children show a left-handed tendency they should be forced to change to right-handedness."

    "Until very recently in Taiwan, left-handed people were strongly encouraged to switch to being right-handed, or at least switch to writing with the right hand. "
    Last edited by a moderator: Apr 24, 2017
  11. Oct 13, 2009 #10
    The bottom line is that there is no answer within the SM view. This is a fundamental problem for the SM (The Matter Only Universe).

    There is another fundamental problem for the SM, the Cosmological Constant Problem, which indicates the solution to both problems.

    If one looks at data, like the measured cosmological constant and look at what various views on the energy of symmetry breaking produces for the cosmological constant there is one obvious pattern

    View 1) Planks - Cosmological constant off by 10^128
    View 2) Electroweak - Cosmological constant off by 10^48
    View 3) QCD - Cosmological constant off by 10^35

    The lower the energy at which the symmetry is broken the lower the theoretical contribution to the cosmological constant. Thus the cosmological constant is not only saying the SM symmetry breaking mechanism is not the correct one, it is saying that the correct energy at which the symmetry is broken is near zero.

    Therefore the symmetry breaking mechanism must one is a symmetrical up/down symmetry like charge is, so that the total, like charge. is 0.

    This implies that there is a mass/up down symmetry. But the SM as it is today can not have any such symmetry breaking mechanism.

    But a mass up/down symmetry also means that there can be a matter only mass creation process.

    So two Fundamental Problems related to the DATA (no antimatter is found=> there must be a matter only creation process, cosmological constant value=> there must be a symmetric mass creation process=a matter only creation process) are both saying the same thing.

    There is an answer, but it is not within the SM view (a view that the data says is wrong) and as such it can not be discussed on this forum.

    There is a difference between fundamentally accurate and fundamentally correct.

    This data is ignored because its saying the SM is only fundamentally accurate and there is a strong SM bias (bigotry?) that refuses to admit this.

    Such a symmetry does exist that is in a peer review jounal, but not one that Vanadium 50considers good enough for you.

    So thank Vanadium 50 for deciding which Physics Journals (in Yale University Library) are good enough for you and which ones are not.

    If you go to Advanced Physics Forums, you can find the information their.

    Last edited: Oct 13, 2009
  12. Oct 13, 2009 #11


    User Avatar
    Gold Member

    This depends of the way you look at it.

    According wikipedia, http://en.wikipedia.org/wiki/Lambda-CDM_model
    \Omega_{\Lambda}\simeq 0.74
    and according http://en.wikipedia.org/wiki/Cosmological_constant
    "is measured to be on the order of 10−35 s−2, or
    [tex]10^{-47} GeV^4[/tex]"

    But, 10^-47GeV^4 is a scale of [tex]1.7 \times 10^{-3} eV[/tex].
    A lot of people has noticed it, but first time I read it from Smolin in a blog comment: it is the neutrino scale. Kamland 2005 measured a delta of 8.8 10^-3 eV.
  13. Oct 13, 2009 #12
    Weird idea: I dont believe that parameters of the Standard Model change it time... except... except the CP violation.

    CP violation means T violation (consequence of the CPT theorem). So, we have very weak T violation now, 14 billion years after the BB. May be that type of violation is just fading away from the BB? Because T-assymetry actually defines a 'special' direction of time on the microscopic level, pointing to the BB or away from it (depending of a view)
  14. Oct 13, 2009 #13
    Universe genesis model...

    http://en.wikipedia.org/wiki/CP_violation" [Broken]
    Last edited by a moderator: May 4, 2017
  15. Oct 13, 2009 #14
    Re: Universe genesis model...

    From http://en.wikipedia.org/wiki/CP_violation" [Broken]
    "One of the unsolved theoretical questions in physics is why the universe is made chiefly of matter, rather than consisting of equal parts of matter and antimatter. ...

    The second of these, involving the weak force, has been experimentally verified, but can account for only a small portion of CP violation. It is predicted to be sufficient for a net mass of normal matter equivalent to only a single galaxy in the known universe. ...

    it would seem that the current Standard Model has gaps (other than the obvious one of gravity and related matters) or physics is otherwise in error."

    Given the accepted problems like the Cosmological Constant Problem, the Gauge Invariance Problem (Nature's mass is gauge invariant but the SM massed formalism is not), and the accepted Renormalization Problem (Feynman - "A dipy process") and the unaccepted fundamental Renormalization Problem (If the model represents Nature, then how does Natures particle renomalize itself, ?mathematically? - mathematics is not physics), and other Fundamental problems, my bet is not that the physics is in error, but that the model is.
    Last edited by a moderator: May 4, 2017
  16. Apr 2, 2010 #15
    I can't believe how stupid that is.
    You'd think being ambidextrous would be good for the brain surely? As humans shouldn't we be trying to use as much of our brains as possible? If nothing else, writing with both hands has got to be good for coordination. Having stronger connections in different bits of your brains can't be a negative thing!

    Sphaleron processes along with the decay of the postulated lightest heavy right handed neutrinos is a possible answer to Baryogenesis. The observation of neutrino oscillations implies neutrinos have mass. One way neutrinos can have mass is via the see-saw model which requires the right handed heavy neutrinos

    The lightest of the Right handed neutrinos, usually denoted N1 or N, decays in a CP violating way. It creates more leptons than anti leptons.

    Sphaleron processes conserve B-L so the excess of antileptons can be converted into an excess of baryons. As the temp cools this freezes out and we are left with an excess of baryons.

    Its far from proven, but its a very plausible candidate. It goes under the Leptogenesis if anyone wants to look it up. I am currently studying it for my Mphys project but am faaaar from understanding it at the level of current research... Although i am getting there slowly... give me a few more weeks and i might have a better grasp! My Project supervisor seems to be one of the main people in the world looking at it, judging by all the papers i have been reading, his name pops up a fair bit.

    The temperatures you are talking about are way too high for particles to form. Look up Big Bang on wikipedia
  17. Apr 2, 2010 #16


    User Avatar
    Gold Member

    You are naively basing your opinion of what is "stupid" upon knowledge that did not exist until very recently.
  18. Apr 3, 2010 #17
    Well when i was at school we were expected to chose a hand very quickly and then stick to it, and they knew all about the differences between the left and right half of your brain and connections and such like. So the existance of the knowledge obviously didn't make a huge impact. This isn't something i know much about, but that fact i can see the benifits of being ambidexturous means that your knowledge doesn't have to be that great to appriciate them.

    Even when people had a much poorer knowledge of how the brain works, i don't see many benifits in forcing a child to chose a hand quickly and then telling them to stick to it. Ok, so they will learn to write neater a bit quicker if they always practice with the same hand, but is it that urgent? If schools are so bothered about how neatly children write then maybe they should consider the situation where a kid, who would potentially write neater with their right hand, was rushed into making a decision and chose their left... and therefore possibly never reaching their potential.

    Kids should be allowed to experiment, what is wrong with leaving it up to a child to decide when and if they pick one hand. Why should adults make a decision on what they think is best for all children, its pretty damn obvious that different things are best for different people... and this is something children should be allowed to explore themselves.
  19. Apr 3, 2010 #18
    Also .... 'right hands were always encouraged'
    I do think thats stupid. General experience in life tells you that different things work best for different people... you don't need any knowledge about how the brain works to see that.
  20. Apr 3, 2010 #19


    User Avatar
    Gold Member

    Again: naive. You have the benefit of retrospecting from the 21st century.
    How can you make such an argument??

    Some people believe that Global Warming is man-made.
    Some poeple believe it is not.
    Twenty years from now the debate will be ancient history, resolved one way or the other.

    And some kid is going to come along and say "It's stupid that 20 years ago, they thought they way they did. They should have known better! Different things work best for different people. It doesn't take brains to see that."
  21. Apr 3, 2010 #20


    User Avatar
    Gold Member

    Again: you have the benefit of retrospecting from the 21st century.
    How can you make such a naive argument???

    Have you never heard the expression: "hindsight is 20/20"?

    Some people believe that Global Warming is man-made.
    Some poeple believe it is not.
    Twenty years from now the debate will be ancient history, resolved one way or the other.

    And some kid is going to come along and say "It's stupid that 20 years ago, they thought they way they did. They should have known better! It doesn't take brains to see what we know now."

    I can give you a million examples where knowledge after-the-fact leads one to see "common sense".
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook