This is probably going to sound like a ridiculous question, but I'll throw it out there anyway. I'm a third year PhD student in particle astrophysics (experimental). As such, almost all of my graduate coursework is in physics (quantum, E&M, stat mech, nuclear, particle, quantum field theory, etc.) rather than astronomy. However, my research is heavily astronomy and high energy based. Let's say I wanted to do a postdoc in experimental condensed matter physics, specifically something relating to superconductivity. Is this reasonably possible, or am I locked in to high energy physics for life?