Hey guys, I'm reading the E&M book from the berkeley physics courses in preparation for my second round of E&M as a junior in undergrad. And they mention some stuff I remember from my intro to E&M class too...namely, that we can use superposition because both gravity and electromagnetism follow inverse square laws. ...Why exactly is the /r^2 a guarantee that superposition works? For some reason it's no longer making sense to me, though I'm sure there are simple arguments as to why it's needed. Thanks for clearing up the relationship between the two. The book actually gives a simple reason why (basically, you need the /r^2 to cancel out the area your gaussian and any other unit would leave a space dependence on the total flux). But I'm wondering if there are any deeper arguments.