Why are most physicists today specialized in particle physics? do most of the physics advancements today have to do with particle physics or something? I thought about specializing in GR but i have no idea whether it's a good choice because most physicists i see in the media are particle physicists i don't know why.. and one more question that has kept me wondering.. I was watching lectures by Leonard Susskind on youtube and he had lectures on various topics, like GR, quantum theory, cosmology, string theory.. he knew a lot of details in each of them, I thought you can specialize and teach one branch, so what's going on? seems like he had studied all of them to me.. so I can study GR and QM together?