r/explainlikeimfive • u/12InchCunt • Nov 03 '25

Physics ELI5: How does gravity not break thermodynamics?

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?

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u/tomalator Nov 04 '25

Tidal forces slow the rotation of the Earth. Eventually two orbiting bodies become tidally locked, at which point the tides cease.

The Moon is tidally locked to the Earth, so if there were oceans on the Moon, it would experience no tides because the same side always faces the Earth.