I'm currently a graduate student doing theoretical physics at a tier 1 school. I'm trying to decide between these two. 1) stay in pure physics PROS: - since I've already taken field theory, I can start doing research quickly - will probably learn some useful simulation skills (I'm considering doing lattice QCD) - I enjoy (i.e. have a great deal of fun) learning physics very much. Taking more theoretical physics classes will allow me to build my analytical skills CONS: - I don't think high energy problems are particularly important for mankind, even though they are pretty interesting to think about. I'm not sure how enthusiastic I can remain for a field that I enjoy doing, but know is pretty unimportant in the grand scheme of things (for society, not the universe) - will most likely have to switch fields after graduation (I don't mind not becoming a professor; I just have no idea what jobs, besides quant finance, are available to people with simulation skills and theoretical particle physics) 2) switch to neuroscience (AI related) PROS: - I think the problems I'll be working on (where does intelligence come from, how does the brain work) is probably one of the most important problems in terms of the big picture - group I'm considering to join seems to be very well funded, students are happy, the PI is a very experienced, very well connected, famous, and works on a large variety of projects - group has a proven track record of placing students at companies and faculty positions CONS: - will have to take a lot of bio + EE classes, possibly like an entire year of classes before actually doing research. This will probably lengthen my stay in grad school by a year or two - Since it's a change in field, I have no idea what methods people in this field use to attack problems. I have no idea whether I will enjoy using these methods the way I enjoy doing physics - I often feel intimidated by colleagues that come from backgrounds closer to this field, like (EE, CS, Neuro, etc) Can anyone please give me some advice? Thanks.