For a career, i.e. graduate-school student and onwards, you pretty much have to specialize in one field. The good news is you're a long way from having to decide which field, because (according to your previous posts) you're in 8th grade now. Even in college/university, bachelor's degree programs (in the US) are mostly "generic", with a core of standard courses that everyone takes (classical mechanics, electromagnetism, quantum mechanics, thermodynamics / statistical mechanics), plus electives on topics that you become interested in, plus math. I think most students don't decide which field they're going to (try to) pursue in grad school until junior/senior year in college.
Even in grad school, students often change their minds. When I started grad school, I thought I was going to do low-temperature physics. I ended up with a Ph.D. in experimental elementary particle physics (specifically, neutrinos).
Your strategy now should be simply to read a lot about physics and expose yourself to a wide variety of topics. Pop-science stuff tends to focus on cosmology, astrophysics and elementary particle physics, but there's a lot more out there, including fields with a lot more long-term jobs.
When I was in college, I joined the Society of Physics Students and got
Physics Today magazine as part of my membership. I still read it today, as part of my American Physical Society membership. Back then I couldn't get very far into most of the articles (some of them I still can't!
) but at least I got an idea of what was going on. Some of it (looks like mostly news and commentary) is available online for free:
http://physicstoday.scitation.org/journal/pto
When I was in college (early 1970s) the Internet didn't exist, and I was at a small college, not a big university, so my options for getting news about physics were limited. Things are different now! Try to aim for professional- or semi-professional-level material, i.e. the stuff that scientists themselves read to broaden their knowledge. Like
Physics Today. I also used to read
Science magazine a lot. Its research articles slant more towards biology etc., but the news articles include a fair amount of physics.
