CP Violation May Explain Why No Antimatter
CP symmetry says that every interaction in particle physics must obey charge conjugation and parity. (If you don’t understand the above statement don’t worry, you just need to know such a symmetry exists.)
Though CP symmetry was thought to be an exact symmetry, it turns out it is violated by weak interactions. If CP was an exact symmetry, there should be just as much antimatter produced by the big bang as matter. However, as we look around us we should be easily convinced this isn’t the case. 
However, since CP is violated, there should have been slightly more matter produced than antimatter. Soon after the big bang every antimatter particle then annihilated itself with a matter particle leaving only the excess of matter which is seen today. This is probably why there is no antimatter.
Explore posts in the same categories: Physics, TheoryTags: Antimatter, Bing Bang, Charge conjugation, CP, CP violation, parity, Weak interactions
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March 1, 2009 at 4:38 am
Will the antiparticles of the living matters unite together after its death with the antiparticles of some others?
March 1, 2009 at 7:40 am
arathis, I am a little confused by the question. There is effectively no more antimatter left in the universe to unite with regular matter.
March 1, 2009 at 11:25 pm
Very good simple explanation here. Keep up the good work!
So, if there was only “slightly” more matter (are talking 60/40 or 51/49?) that must mean that there was a hell of a lot more mass produced in the big bang than even the massive amount now
But would this mean the gravitational waves from this enormous amount of mass still be propagating now? If we can see stars from just after the big bang (a la Ultra Deep Field) is it not reasonable to assume that these gravitational waves, being far in excess of the type we see nowadays, would still be detectable?
I’m a 16 year old armchair physicist, so excuse me if I sound like I read too much popular science xD
March 2, 2009 at 4:40 am
We do believe there is a gravitational wave background left over from the big bang. We have not detected it yet as it is very hard. Several experiments will go on over the next couple decades to try to detect them. We are hopeful that this gravitational wave background will allow us to peer directly at processes which happened right after the big bang like inflation.
March 3, 2009 at 1:28 pm
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March 4, 2009 at 12:24 pm
ah, CP violation has a place in my heart, since it’s my experiment’s cash cow (the experiment i work on is headed by the guy who got the nobel for this…that award brings in the bucks in a pinch, i tell ya). way to bring it to the forefront of the discussion!
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