Not just for theoretical physics,
but for ASTROPHYSICS.
The Big Bang Theory Season 8, Episode 6
I have a doctorate in ASTROPHYSICS
and I'm every bit as awesome
The Big Bang Theory Season 10, Episode 11
This is Dr. Rajesh Koothrappali
from the Astrophysics Department.
The Big Bang Theory Season 6, Episode 20
I have a PhD in ASTROPHYSICS.
The Big Bang Theory Season 10, Episode 18