a very broad subject

Protection of the family and of children is a very broad subject.

A. Compared to physics or chemistry, mathematics is a very broad subject.

Wikipedia has come a very long way since 2001, when the entry for physics simply read "a very broad subject".

Back then, the entry for "physics" said simply "Physics is a very broad subject".

It's just, um, it's a deep subject to talk about, a very broad subject to talk about, but being spiritual beings, I guess the shortest way of saying it.

Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

Also, politics is a very broad subject area; e.g. at the University of Manchester I had options in ethics, media and politics, economics... I also would say that your employment prospects are likely to be better.