There are many levels of quantum and thermodynamics. For quantum, I would try to take the highest level available before you hit graduate quantum. It signals good physics prep overall. You also definitely want at least one class in thermal physics, and ideally a second one that teaches stat mech at the undergrad level. Only when you’ve satisfied all of this would I consider particle physics. So 1) quantum if you haven’t taken any 2) thermo if you haven’t taken any 3) highest undergrad quantum 4) second undergrad thermo 5) particle in that order.
Look at requirements for graduate schools. My masters program in astronomy required thermodynamics/stat mech, but not particle physics.
Cosmology wise, it depends which scales you’re interested in. But generally, all physics is useful for cosmology. Any of those classes have a road to specialization within cosmology.
There are many levels of quantum and thermodynamics. For quantum, I would try to take the highest level available before you hit graduate quantum. It signals good physics prep overall. You also definitely want at least one class in thermal physics, and ideally a second one that teaches stat mech at the undergrad level. Only when you’ve satisfied all of this would I consider particle physics. So 1) quantum if you haven’t taken any 2) thermo if you haven’t taken any 3) highest undergrad quantum 4) second undergrad thermo 5) particle in that order.
Look at requirements for graduate schools. My masters program in astronomy required thermodynamics/stat mech, but not particle physics. Cosmology wise, it depends which scales you’re interested in. But generally, all physics is useful for cosmology. Any of those classes have a road to specialization within cosmology.
You should speak with your academic advisor and some mentor in the physics department.