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You Wrote:

I would like to receive information on the smallest parts of matter to date.


Dear Kerensa,

All the matter surrounding us can be explained by three particles, the smallest building blocks: up quark, down quark and electron. The quarks combine to form protons and neutrons. Those then form atomic nuclei, which attract electrons.

Physicists think of quarks and electrons as not having any size or diameter: they are point-like particles surrounded by a force-field. When putting these particles together, we obtain objects that have spatial dimensions like protons and atoms.

For whatever reason, nature has elected to have six quarks. To first approximation, only two of these show up in the matter that surrounds us. But taking a closer look, the four other types of quarks contribute in form of quantum effects.

The electron also has relatives. To learn more about them, I recommend that you check out one of the two following Web pages:

Only by building better "microscopes" - very powerful particle accelerators - we will be able to find out whether these are really the smallest building blocks. Perhaps they are composed of even tinier particles. So far we have no indication that that's the case. But fifty years ago scientists also believed that protons are fundamental particles. Well, as I explained above, they are not. We may be in for yet another surprise.

Best wishes,

Kurt Riesselmann
Fermilab Public Affairs

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last modified 4/23/2002