In the podcast, it's mentioned that two pulsars that gravitate around each other and also approach each other. It is said that they are getting closer and closer because the system is loosing energy and that energy is used to create gravitational waves.

Now this bring me back to basic physics which talks about all the fun and provocative ways to lose energy: friction, air resistance, and so on.

Apparently, to build a perpetual motion system you need something like frictionless material in a void. But even if you had that, the system still wouldn't work because it's losing energy in the form of gravity ways.

Does that make sense ?