18
May
10

Why we matter (but don’t antimatter).

Fermilab's particle accelerator, the Tevatron

Fermilab's particle accelerator, the Tevatron.

Or, rather, why there is a matter dominance in the Universe. You see, in the very early universe there was alot of matter and antimatter, but when matter and antimatter meet they anihilate each other. And that’s what happened! It was very dramatic, I’m sure. But we’re here, so there must have been some matter left over after this huge anihilation — meaning that, for some reason, there was more matter in the early Universe than antimatter. This is called, in techical terms, “CP violation,” as this apparent matter dominance in our Universe is a violation of two physical symmetries, charge (hence the C) and parity (hence the P — parity is the symmetry between right and left). We love symmetries in physics, and when they’re violated, we go “whaaaa?” and want to know why.

Now, why was there a dominance of matter over antimatter in the early Universe? It turns out that the good folks at Fermilab Tevatron (the second most powerful particle accelerator after the LHC, located in Illinois) might have just found out. Here are some places to read more:

(1) New York Times article, “A New Clue to Explain Existence,” sent to me by my most excellent physics adviser and mentor Gary Felder.

In a mathematically perfect universe, we would be less than dead; we would never have existed. According to the basic precepts of Einsteinian relativity and quantum mechanics, equal amounts of matter and antimatter should have been created in the Big Bang and then immediately annihilated each other in a blaze of lethal energy, leaving a big fat goose egg with which to make stars, galaxies and us. And yet we exist, and physicists (among others) would dearly like to know why.

(2) From the blog Uncertain Principles, “Why do we have stuff? Hints from Fermilab.”

The physics issue in question is why we have more matter than antimatter in the universe, as symmetry would seem to demand they be created in equal amounts in the Big Bang. Had that happened, though, all of the matter should’ve annihilated with the antimatter very quickly, leaving us with a big empty space full of photons and not much else. So there must be some breaking of fundamental symmetries, the technical term for which is “CP-violation,” in order for there to be all the matter we see around us.

(3) A great post from the blog the Great Beyond (which I haven’t heard of before, but this is a great post — great, short explanations): “Making More Matter.”

(4) A bit higher level, from the RESONAANCES blog, “New Physics Claims from D0!” (RESONAANCES is a great blog if you actually have a physics background, otherwise it’s… you know… kinda gibberish.)

(5) Well, im not sure how much fun this will be, but if you’d like to look at their paper, you can find it on SPIRES (the Stanford University high-energy physics papers archive) here. It’s called “Evidence for an anomalous like-sign dimuon charge asymmetry.” …Fun! Well, reading the introduction might be cool.

Enjoy!

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