I'm starting grad school this fall - direct entry PhD in astronomy & astrophysics. I eventually want to do theoretical cosmology, although im not sure in what capacity yet. In the 5 years of the program, we're only required to take 4 classes, and they can be pretty much whatever, as long as they're approved. Should I take the Jackson level E&M course if I don't have to? Is it going to be useful, or just torture?