# Fermilab

## Inquiring Minds

The particle model of matter

You Wrote:
I am a junior high student that has ben assigned to ask the people at Fermi Lab these questions. I would be grateful if you or someone else could send me some reply info. Thank you.
1. do you think the particle model of matter is true? Why?
2. If all matter is made up of particles, then what are particles made up of?

My name is Andrew Green and I am one of the experimenters at Fermilab. I am actually a graduate student here. I am pleased to see that you are interested in this, and I will do my best to answer your question, but it is actually quite a hard (and excellent) question.

Up to this point in physics, experiments have shown that matter can be thought of as being made up of indivisible "bits" or particles. There is a model, called the Standard Model, which says that all matter is a model, called the Standard Model, which says that all matter is composed of quarks and leptons. The quarks are called up, down, charm, strange, top and bottom. The leptons are called electrons, muons, and taus. So far, nobody has been able to see that the quarks or leptons are made of anything else. Our experiments give us the ability to "take pictures" in a way, of these different particles. When an object like a proton is "looked at" at one of the experiments at Fermilab, it is seen to be made of three quarks. When the quarks are looked at, no smaller particles can be seen. This does not mean that they are not there, though.

I hope that this begins to answer your question. I would like to further discuss it if you wish, since it can go in many directions, like: "What is a particle?" Can *you* answer that? What does "particle" mean to you? Does a particle have to be of a certain size?

Sincerely,
Andrew

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