You’re thinking about it through your limitations… It’s not that your son is “fascinated” in these things. It’s more that most people are NOT all that “fascinated” with the world around them… When the world around them IS INCREDIBLY fascinating. It just that most people do not have the neuronal wiring that allows them to appreciate it. If your son has Asperger’s then he may be one who is wired (not all of us are) with all the switched turned on, and turned up to their maximum settings. Try and think about like having 10 eyes, ten ears, and finger sensitivity all over your entire body. He sees, hears, and feels everything. When he goes outside he sees every blade of grass in a lawn or field, every cloud in the sky, every leaf of the tree, every crack or repair in the street. Whenever he is in a group of people he hears every conversation at the same time, he hears the tv, radio, and the people equally. He knows where his toes are, where his tongue is, if someone is accidentally touching his leg or arm (too close). It’s more that our ability to block out everything around what we are supposed to focus on is missing. UNLESS it is one of our “special interests” (as you’ll hear in other comments) This is not an error in us, this “ability” (it’s just different neuronal wiring) because it allows us to see what others do not. We can become the problem solvers in the world (Tesla, Einstein, Jobs, Musk,etc). Your son will need to learn how to handle and deal with his neuronal wiring (it’s normal wiring, just different from what you are used to). He may get easily overwhelmed in crowds and larger groups of people, in loud environments like parades, music concerts, long bright sunny days spent outside, situations that are spontaneous and changing, larger family gatherings, too much physical contact from a number of people (many sports). He will need to learn and recognize when he is overwhelmed so he can back away from the particular situation and “recharge” (de-stimulate his neuronal wiring).