• Question: Hi, Where do you personally believe that anti-matter comes from, do you believe in the theory that there's a constant sea of anti-matter surrounding us? and what are your views on the theory that our universe came from Majorons from possibly a fourth dimension and therefore split into both matter and anti-matter, how does this explain the possible excess of matter? Could this mean that the possible collision of universes/ dimensions is the reason behind the begining of the universe? (sorry, of course I realise all of this is theoretical!), Thanks

    Asked by domreeves to Amy, Drew, Julia, Kimberley, Sara on 21 Jun 2011.
    • Photo: Drew Rae

      Drew Rae answered on 20 Jun 2011:

      Hi Domreeves,
      When cosmic rays hit the earth’s atmosphere, the collisions create anti-matter. We know this because we’ve been measuring it since the 1930’s. The anti-matter particles don’t last for long though.

      The physics suggesting that there is a lot of anti-matter in the universe is fairly solid too. You don’t need a fourth dimension to explain this though, it is a natural consequence of the Standard Model and the Big Bang.

      There’s nothing to stop the Big Bang having a cause such as a collision of universes. The trouble is that we can’t test to see if this is the right explanation, so it’s just speculation.

    • Photo: Amy MacQueen

      Amy MacQueen answered on 21 Jun 2011:

      This is an incredible question Dom and I really don’t know enough about it. I’ll leave it to those with more knowledge on physics and space! 🙂

    • Photo: Julia Griffen

      Julia Griffen answered on 21 Jun 2011:

      Hey….Wow this question is pretty far out there…some big science theories.. I dont know all the in’s and out’s of all the theories, you sounds more of an expert than me.. However I dont think scientist know all the answers, just yet any way.. we have come across this thoery of anti matter and new thoeries and maths to explain them come along more often.. I think more theories will come along and more unexplained things will be discovered too!! …Sorry can;t give much insight sorry.. physics isn;t my strong point 🙁

    • Photo: Sara Imari Walker

      Sara Imari Walker answered on 21 Jun 2011:

      Hello domreeves! Awesome question! Cosmologists actually have a pretty clear picture on this issue, and its quite intriguing. In the very early universe their was likely a nearly equal amount of matter and antimatter. But it was not exactly equal! The asymmetry is thought to have been 10^-87 in favor of matter. This is very very tiny! Combining this asymmetry, with laws of physics that just slightly violate matter-antimatter symmetry (i.e. production of matter particles might be slightly favored over their antimatter counterparts) and non-equilibrium conditions (the universe was far from equilibrium as it cooled!), can lead to the current state of a matter dominated universe we observe today.

      There are several reasons why we think the entire visible universe is matter dominated. For one, matter and antimatter annihilate when they come in contact producing photons (i.e. electromagnetic radiation). So they are fine apart, and behave and certainly look the same. BUT when together they produce radiation with a very clear single. It could be possible that large regions of our universe started with an asymmetry favoring antimatter and that their may be huge domains of the universe where there are only antimatter galaxies. But we don’t observe bright spots in the sky where the antimatter domains met the matter domains. This suggests the universe is dominated by matter everywhere.

      This is not to say their isn’t antimatter out there though! As Drew has said, we see antimatter in cosmic rays all the time. Also, it was just recently discovered that thunderstorms might make antimatter. Antimatter is produced through particle interactions – particularly high energy ones, which make matter antimatter particle pairs to conserve several quantum numbers (such as electric charge for one – eg positrons and electrons have opposite charge). So there is some antimatter everywhere but its not a lot.

      Long story short -yes their is antimatter everywhere, although it is minute (thankfully! we wouldn’t be here if it wasn’t). The reason for the initial asymmetry in the early universe is the real mystery. Figure that one out and you may earn yourself a Nobel!!