Sorry, this is probably a dumb question but I am new to physics so forgive my ignorance. I learned in class that when a person touches something, or any two objects touch each other for that matter, the force interaction is actually due to the electrons repelling each other. So I wondered what would happen if two particles with no charge (such as neutrons) collided. Would they actually collide without having opposite forces interacting? Would they pass through each other? It makes me wonder what matter actually is if there is no collision. I asked my professor this question but he didn't have an answer. Any help would be appreciated.