How did scientists prove that quarks exist?

[Karimspencer]

I heard that it had something to do with acceleration in a huge accelerator in fermi-lab but where they can collide going at speeds close to the speed of light , but how does this collision help. Or is this not the way they used?

 

[mfb]

First: You cannot "prove" something in physics. It is possible to falsify a theory by experiments. But if experiments and theory agree, this does not prove the theory. If many different measurements are in agreement with predictions from this theory, it is a good theory. But it can never be proven.

How did they invent the theory? They analysed the particles produced in these collisions. In high-energy collisions, a lot of particles are produced. Before the quark model, they were all considered as elementary particles, and soon 30+ of them were known. But then they found patterns in their properties. The quark model was able to explain those patterns with just 4 (today: 6) quarks, and to predict the existence of new particles, which were found later.

It is possible to calculate a lot of properties of the particles with the quark model. And up to now, no serious deviation from these predictions was found.

 

[Karimspencer]

So could scientists predict what what are quarks made out of(if they were made out of something) by making high-energy collisions of quarks?

 

[mfb]

You cannot accelerate individual quarks. If quarks have some sub-structure, it might be possible to see this in proton-proton collisions. So far, no substructure was found, which sets lower limits for the relevant energy scale (~TeV).

 

[Karimspencer]

oh ok