Why does our universe have more electrons than positrons?

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  • Thread starter Leo Liu
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Main Question or Discussion Point

In the known universe, the number of electrons seems to be greater than that of positrons since electrons are within every atom around us. However, when a gamma ray approaches a nucleus, a pair consisting of an electron and a positron, can be created from pure energy. If all matters are created from energy, why don't we see an equal quantity of positrons and electrons?
 

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phyzguy
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Note that an average cubic meter of the universe today contains approimately 1 hydrogen atom and 1 billion CMB photons. So at one point there were nearly equal amounts of matter and anti-matter, but approximately 1 part per billion more matter than antimatter. The matter and antimatter annhilated, creating photons, and the fact that matter that remains today is due to the slight (1 part per billion) excess of matter over antimatter. As @Drakkith said, no one really knows why there was slightly more matter than antimatter.
 
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