Question: Can you look inside protons, electrons and neutrons yet?

Baptiste Ravina answered on 6 Mar 2020:

Very interesting, but tricky question 🙂 Let me answer you in a few steps…

1) “Can we look *inside* particles?” – not really, we don’t have that kind of technology yet. But what we can do is come up with a theory of what *might be* inside those particles and test it in the lab. That’s what I do, and indeed we can observe particles smaller than atoms. It’s a bit like the difference between kicking a football and a basketball – even though you’re not really “looking inside” them, you can feel the difference in the material or see how much farther one goes.

2) “Can we look inside protons and neutrons?” – in the way I explained above, yes! We now know that protons and neutrons are made of smaller particles, called “quarks”. These quarks form a new family of particles. For instance, a proton is made of two quarks “up” and one quark “down”; a neutron of two “down” and one “up”. For now, we don’t know if quarks are the end, or if we can go even deeper. A very strange phenomenon about quarks, is that they can’t exist on their own – they absolutely must group together to form these heavier particles, like protons and neutrons. This is very peculiar and not quite understood yet. (In fact, if you manage to prove mathematically why that is the case, you win a 1 million dollar prize!)

3) “Can we look inside electrons?” – no. As far as we know, electrons are fundamental particles, they can’t be broken up into smaller pieces. This is a very useful thing too, because it means we can use electrons to do a bunch of stuff (like electronics) without having to worry they might suddenly “change” or disappear.