Monday, January 26, 2015

particle physics - how do we know that the base of entire universe is the proton (hydrogen) and not the antiproton?


It may be that the base of a part of the world is anti-proton, We've always been on the planet Earth and the Milky Way.


how do we know that the base of entire universe is proton (hydrogen atom)?



Answer



There are two parts to this question. One is a question of naming conditions. If matter and anti-matter were created with equal probability (as they are in many processes) then it would just be a matter of convention as to which way we name them (meaning there wouldn't be a truly natural way to distinguish a proton from an anti-proton).


However, as it is not always true that matter and anti-matter production is identical in all processes, this leads to the second part of the question, why is there a preference of matter over anti-matter (where we use the standard convention for names). Charge Parity violation (CP violation) was predicted and observed in certain weak processes that lead to a "handedness" to the universe, which helps explain some of the imbalance, but not enough of it. In order to explain the imbalance seen in the universe, there should be CP violation observed in the interactions governed by the strong force. However, it has not been seen to date, although it might just mean that we have not yet probed to high enough energies to see it.


note: this is just a self reminder to revisit and reword


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