
And, of course, it's Gravity Probe B.
The Big Bang Theory Season 1, Episode 13

The idea that you might be able
to incorporate GRAVITY...
The Big Bang Theory Season 2, Episode 6

Well, as long as it has a healthy GRAVITY
and all its moons, I'll be happy.
The Big Bang Theory Season 9, Episode 12

Besides disrupting the local GRAVITY field.
The Big Bang Theory Season 1, Episode 6

And how you threw up
in zero GRAVITY,
The Big Bang Theory Season 7, Episode 16