2012-08-05 09:55:25 +00:00
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<h1>The Three Generations of Matter</h1>
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2012-08-05 08:51:33 +00:00
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2012-08-05 09:55:25 +00:00
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So far we have met the particles that make up most of the matter we
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see all around us - the up quark, the down quark and the electron. We
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have also met the electron neutrino, which is emitted during
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radioactive decay. It seems like these four particles, along with the
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particles that carry forces, are enough to explain everything.
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2012-08-05 08:51:33 +00:00
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2012-08-05 09:55:25 +00:00
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<p>It turns out that each of the matter particles has two "big
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brothers" – new particles that are identical except for their larger
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mass. Physicists talk about "three generations" (sometimes called
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families instead) of matter. The first generation is the particles we
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have met already. The second generation contains the charm quark (the
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big brother of the up quark), the strange quark (the big brother of
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the down quark), the muon (the big brother of the electron) and the
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muon neutrino (the big brother of the electron neutrino). The third
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generation is the top quark, the bottom quark (this is sometimes also
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called the beauty quark), the tau lepton and the tau neutrino.</p>
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