Soon after the Big Bang we expect there should have been roughly equal amounts of matter and anti-matter.  But if that were the case those two kinds of particles would come together and destroy each other and you might be left with just a sea of radiation.  We know that’s not the case because we’re here.  So the universe today is dominated by matter.  How did that come about? 

How did matter come to dominate over anti-matter?  That’s one of the biggest and most difficult questions that both physicists and cosmologists have.  They have some ideas as to what might be responsible but they don’t really know for sure.  

One of the more compelling explanations is that the predecessors of today’s neutrinos might have played a role in causing that asymmetric.  The reason for that is that maybe the neutrino and its anti-matter twin don’t behave exactly the same way.  They might behave the same way or they might not.  And if they don’t, that might give us a way of accounting for explaining how matter came to dominate over anti-matter in the early universe. 

In Their Own Words is recorded in Big Think's studio.

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