I wholeheartly agree, the potential opening of understanding caused through consideration of gravitational-repulsion between matter and antimatter (or “anti-gravity,” I hate that term) will be the next biggest thing, putting LHC on the back burner. I am very hopeful for the AEGIS experiment to prove the reality of gravitational-repulsion.

Why? Because I am in process of advancing a deduction-produced new cosmologic model that is completely seamless from end to end. Unlike current assumptions, all verified/concrete data is compatible, i.e., there are no paradoxes between theory and the physical record.

View, follow, and join the ongoing debate at: http://hypography.com/forums/alternative-theories/18910-the-dominium-model-by-hasanuddin.html

http://arXiv.org/abs/astro-ph/9707087

shows that:

We ask whether the universe can be a patchwork consisting of distinct regions of matter and antimatter. We demonstrate that, after recombination, it is impossible to avoid annihilation near regional boundaries. We study the dynamics of this process to estimate two of its signatures: a contribution to the cosmic diffuse gamma-ray background and a distortion of the cosmic microwave background. The former signal exceeds observational limits unless the matter domain we inhabit is virtually the entire visible universe. On general grounds, we conclude that a matter-antimatter symmetric universe is empirically excluded.

“In fact, this asymmetry between matter and antimatter can be made quantitative (for baryons such as protons and neutrons) through observations of the abundances of light elements in the universe (Big Bang Nucleosynthesis – BBN) and also from the pattern of anisotropies in the cosmic microwave background radiation (CMB)”

I can still imagine a universe where zones of matter and antimatter are so far apart that we don’t experience the annihilation of these opposites. The possible symmetry would feel so much better.

Or what if Dark matter is over proportionally Anti?

Where should I look to find references on how to conclude that there must be an asymmetry?

Thanks Ben

One possibility is that it does so because of the dynamics at the end of inflation (and never becomes matter-antimatter symmetric). A number of people (including me) have worked on various versions of this idea (and I may write about them at some point).

But if baryogenesis doesn’t work this way, then in the absence of a chemical potential, eventually baryons and antibaryons will have abundances determined purely by their masses (since they will be in approximate thermal equilibrium). The CPT theorem then says that their masses are identical and therefore their abundances are identical. Thermal fluctuations of these numbers would mean a small random asymmetry at any given moment, but one far smaller than observations require.

Hope this helps.

[itex]
\sum_i B_i~=~0,
[/itex]

where the positive and negative baryon numbers cancel out in a sum over all particles. This means there is no net quantum number for baryons, which makes things nice. However, in our later universe this is no longer the case and the summation is positive. So somehow there is a net “creation” of these quantum numbers. It is also interesting to note that these numbers have some topological content as well. So by symmetry breaking these quantum numbers (B) were created with a net positive value, and the “lost” negative counter parts are in some ways either destroyed or buried away in a form we can’t observe.

As for the equivalence principle, that is an interesting question. The Baryon number can be modelled in a simply spinor model. Experiments have demonstrated that photons with different helicities or spins will pass through certain material differently. The index of refraction is modified by a spin quantum Hall effect, and gravity has an optical analogue. Photons with different spin directions might actually become optically split! One might then wonder if there is an analogous physics where protons and anti-protons might have paths in curved spacetime which differ slightly.

Lawrence B. Crowell

Please pardon my ignorance. But why is it postulated that the early universe had nearly equal amounts of matter and anti-matter?

Thanks,
Saurabh

a) Most nucleosynthesis theories call for equal amount of matter and anti-matter at high energy condition of early universe because symmetry transformation that permits them to be created were more feasible.

b) Later, with a lower energy universe, the symmetry was broken, halting further conversion of matter and anti-matter into each other.

c) These then combine and all matter stuff should therefore be eliminated.

Puzzle: How come we have so much matter and none anti-matter?

Contradiction: The symmetry either does not exist or wrong. Because if one takes the current universe and run it backward in time to the big bang condition, you won’t get back the original universe in term of amount of energy.

I did specifically refer to photons, and there is, of course, a fundamental difference between massless particles and massless ones that is somewhat relevant here. In fact, what ends up being relevant in calculations down the line is the baryon to entropy ratio, and most of the entropy is in photons.