Per the standard model, we currently have four kinds of interactions - electromagnetic, weak, and strong nuclear interactions & gravity (?) What are fields? How many of them are known? For gravity, we need a mass to create a field and it does not pervade all of time-space (?)....i.e. it effects reduced with distance from the mass. So mass is the source for creating the bend/gravity in time-space. What about Higg's field? what is the source? Moderator: I just realized, after posting, that this topic falls in particle physics as well.