I'm a freshman at UT Arlington and I will get my undergraduate degree in Physics from that university. Now, I am sure that I want to pursue Physics, but not quite sure of the sub-field. I lean towards Astronomy a lot, and I will probably end up doing that. The problem is that my university doesn't have a lot of Astronomy going on (it is relevant, but not exactly great). Though, It has one of the best High Energy Physics (HEP) departments in the country and there's tonnes of research happening there. Based on these facts, there are three clarifications I require and I'd highly appreciate it if you could help me out: 1) How do I decide which sub field I like the most? The reason why I ended up picking Astronomy is because I took an online 1st year course from ANUx and loved it so much. 2) Will it be a good idea to switch from Astronomy to HEP because my university is focused more in that field? 3) Will it matter which sub-field I did my research in when applying to Grad School? Like, if I do some research in HEP during undergrad and then apply for an Astronomy program, will it count?