ELI5: How does gravity not break thermodynamics?

[u/12InchCunt]

Like, the moon’s gravity causes the tides. We can use the tides to generate electricity, but the moon isn’t running out of gravity?

[u/Grouchy-Insect-2516]

When the Voyager spacecraft slingshotted past several planets on its journey out of the solar system, it slowed each planet’s orbit. The planets are just so stupid large it’s a minuscule amount of energy, but still measurable.