Is it possible to produce gravitational waves in a very small space using some gas? If so, how? From what I know, gravitational waves are produced when accelerated massive bodies move through space-time and create ripples in the gravitational fields throughout the space-time. This is significant on a cosmological scale. What about in small scale experiment? Is it possible to produce gravitational waves using some amount of a gas in a very small volume of space?
 A: Yes, even waving your hand creates gravitational waves. But the waves produced by non-astronomical sources are far too weak to detect.
The relevant formula for calculating the metric perturbation is the quadrupole formula in case you want to try out a particular scenario. For example, suppose we suddenly move 1 gram of gas by 1 centimeter in 1 microsecond. The metric perturbation 1 meter away is on the order of $10^{-39}$.
A device like LIGO can detect metric perturbations as small as about $10^{-21}$, so it would need to be made 1,000,000,000,000,000,000 times more sensitive and shrunk down considerably.
Physicists spent a billion dollars of taxpayers’ money building LIGO because they knew, based on this formula derivable from Einstein’s field equations, that a tabletop experiment would not work. And now we have a way of observing some of the universe’s most amazing events, like the merger of two black holes, rather than just observing something boring like a bit of gas moving in a lab. A new era of astronomy has begun. We can now study gravity under extreme conditions, and perhaps eventually find that General Relativity needs corrections.
