system
Given the following post, respond as if you're commenting on Reddit:
human
How is mass converted to the energy of gravitational waves?

In the recently detected waves, three solar masses worth of black hole ... stuff ... was converted into gravitational waves. But any two masses orbiting each other produce waves, even if they're undetectable. Those waves are carrying energy, which apparently comes from a reduction of mass in the system. How does that work? 

I'll pick an example: the earth-moon system is radiating gravitational waves at a frequency of about 4 x 10^-7 hertz at some teeny tiny eentsy beentsy wattage. Is the ordinary, non-black-hole-matter mass of the system shrinking by that same wattage? How?
gpt
Gravitational waves decrease the kinetic energy of the bodies, not by taking away mass. It's like a ping-pong ball bobbing in a pool of water. Over time, the amplitude of the bobs goes down, corresponding to a loss of energy of the ball (eventually it settles down and stops oscillating). That energy goes into the ripples in the pool.