Comment by computerex

There is an entire theory that describes the strong interactions inside the proton. Please take a look at https://en.wikipedia.org/wiki/Quantum_chromodynamics and experimental evidence for QCD: https://en.wikipedia.org/wiki/Quantum_chromodynamics#Experim...

Furthermore particle accelerators have been smashing protons for a long time to probe what's happening inside. The standard model of particle physics is validated by evidence and experiments. I don't think it is fair to say that we don't know what is happening inside a proton. There are many questions in physics still left unanswered but I don't think anyone would classify this as such.