Cake
• Woah. So...can someone smart explain like I'm 5 how "motion and confinement" result in mass?

In my head I'm envisioning quarks and gluons flying around in a really tight space and bouncing off of each other, but I don't understand how this could result in the creation of mass. I guess I've always thought of mass as a measurement of an amount of stuff, not a measurement of what that stuff is doing.

• There are some lovely equations called the Lorentz Transformations that explain how, as mass moves at speeds approaching "c", the speed of light, the length of the mass decreases, the time experienced by the mass slows down, and most importantly in the current situation, the mass increases. Much of the mass increase inside protons and neutrons is because the quarks are moving so FAST. Once you accept the Lorentz Transforms, that becomes the easiest of the various mass contributions to grasp, I think. The others are variations on the same theme - that there is this equivalence between energy and mass, thank you Einstein, and inside protons we cannot readily sense or release that energy, but now we can tell that it is giving rise to sensible mass.