[RightWhale]

how would one modulate

Mass has to move. Perhaps a rotating double star would give off CW strong enough to detect. Perhaps Jupiter is massive enough and close enough for the instrument to pick up something.

[MonroeDNA]

OK, here's a question I've been asking various people for over 15 years:

Einstien stated that there is no way to measurably differentiate between gravity and accelleration.

Newton invented calculus to prove that any gravitational mass can be treated as if all the gravity was coming from a single point, at the center of mass. A point source.

Let's suppose that you were in an elevator, under either accelleration or gravity, and you hung two static pendulums from the ceiling, from strings.

My question: Under gravity, wouldn't the pendulum strings angle toward each other, exactly towards Newton's common point? But under accelleration, wouldn't the strings would be perfectly parallel?