# Use of the density function in physics

For continuos groups one introduces a density function for an invariant measure when summing over the group elements.

I learned a little about these concepts in a pure mathematical book.

I was thinking about their utility in physics.. I know they probably do.. What physical areas could these concepts be used in?

martinbn

jim mcnamara
but I really don't know of any examples, that's why I'm asking for them.

martinbn