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Q & A: smallest particle?

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Most recent answer: 10/22/2007
Q:
Is there a limit on how small a particle can get? I mean first people thought the atom was the smallest particle, then they found electrons and protons. Then quarks and gluons. quarks are probably made out of something and so on. Is this cycle infinite? Im guessing eventualy you will end up with pure energy.
- Enrique Aleman (age 22)
CT, USA
A:
We have to resort to some guesswork to answer your question. We suspect that there is a limit to how small anything can be, because on a very small distance scale the combination of quantum mechanics and General Relativity goes haywire. Roughly speaking, if something is very small, it has a big momentum spread and a lot of energy. But if it has a lot of energy in a little space, a black hole forms. For a given amount of energy there's a minimum size of black hole. Those sorts of problems seem to make it impossible for things to be smaller than about 10^-33 cm.

There's really a second question in there too. Will the chain of explanations always face another level of mystery, or will it finally hit a rock-bottom 'theory of everything'? That's easy to answer: we just don't know.

Mike W.

(published on 10/22/2007)

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