Biophysics

Recently on a bender dressed as a schoolgirl I bumped into my ex-boyfriend who recently started studying at I think it was Imperial though I'm not quite sure as I was in a bit of a drunken daze, anyway he was going to study Astrophysics but then decided to do Biophysics.
What is Biophysics, as my friend has recently told me, "no it's nothing to do with people and goats falling off cliffs"?
I never did have much of a head for science except Biology, anybody want to shed light on this for this rather daft young lady?