
She thought if I failed at THEORETICAL physics
that I should have a trade to fall back on.
The Big Bang Theory Season 2, Episode 10

Of course not.
I'm a THEORETICAL physicist.
The Big Bang Theory Season 2, Episode 23

...to succeed in THEORETICAL physics.
The Big Bang Theory Season 2, Episode 6

...THEORETICAL physics is... What's the word
I'm looking for? Hmm, cute.
The Big Bang Theory Season 4, Episode 3

as a THEORETICAL
physicist,
The Big Bang Theory Season 7, Episode 20