...as the SURFACE of
an n-dimensional superfluid.
The Big Bang Theory Season 8, Episode 23
in the Earth's
SURFACE.
The Big Bang Theory Season 7, Episode 3
what do you say we get back
to SURFACE tension of domain walls?
The Big Bang Theory Season 9, Episode 10
...on a SURFACE located
at the farthest reaches of our cosmos.
The Big Bang Theory Season 6, Episode 5
If there is life beneath
the SURFACE of these planets,
The Big Bang Theory Season 11, Episode 10