We used to think that atoms were the fundamental particles, made up of nothing smaller, but then we discovered the concept of sub-atomic particles who themselves were now fundamental, but now it has been concluded that quarks make up all of these and they themselves are indivisible. Each time we were wrong and the particles could be broken up smaller and smaller, how do we know this time for sure that quarks are fundamentak?
In: Physics
> how do we know this time for sure that quarks are fundamentak?
Because we can test for it, such as experiments with the LHC.
For example suppose you have an atom and you think it might be fundamental. If we put some energy into it we can get an ionized atom which indicates it has internal components. Similarly we might be able to excite the atom, pushing one of its electrons to a higher orbital and measuring the loss of energy as the electron drops back down. All of that would indicate the atom is not fundamental.
For quarks if we crash protons together with the LHC the component quarks can interact, and if the quarks are not fundamental it might produce an “excited quark”. When that quark decays it would be measured by sensors in the LHC and would indicate that there was some kind of internal structure to the quark, just like with the atom.
However we measure no such signal so it is reasonable to conclude that quarks are indeed fundamental particles.
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