How capable is a PhD student supposed to become?

[TomServo]

I'm in gravity (cosmology, GWs, etc.) and starting my fourth year and only just recently took GR for the first time. I'm wondering what standard I should set for myself WRT GR. It feels like you'd need to be an expert in GR just to identify worthwhile problems to work on, and I'm expected to have a PhD in two years.

When you get your PhD, are you expected to be an expert not just in your thesis topic, but your field too? Should I worry if I understand GWs but don't understand black holes so well, to pick an example?

 

[Dr. Courtney]

These are questions for your thesis adviser and the faculty at your school.

The graduate school I attended required that PhD candidates pass an oral examination in their area of specialty, which for me was atomic physics. The faculty and other grad students in atomic physics were able to provide sufficient guidance to allow me to adequately prepare for this exam.