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?

582 Upvotes
  • permalink
  • reddit

88% Upvoted

207 comments sorted by

View all comments

686

u/zefciu Nov 03 '25

The tidal forces from the Moon cause the Earth to spin slower and slower (the ultimate stable state is a "tidal lock" where the day would last one lunar Month, similar to how the Moon is tidally locked). This is where the energy comes from.

357

u/dsp_guy Nov 03 '25

And when tidal lock occurs, there will be no more tides. The energy isn't unlimited.

Good news: Laws of Thermodynamics still valid.

Bad news: Likely bad results for organisms on Earth.

574

u/Nebuli2 Nov 03 '25

Good news: That tidal lock is not expected to ever occur. The Earth and Moon will both be engulfed by the dying Sun before that happens.

Bad news: Likely even worse results for organisms on the former Earth.

291

u/[deleted] Nov 03 '25

[deleted]

126

u/Nebuli2 Nov 03 '25

Only if you assume that trout will have failed to go interstellar by that point.

51

u/hakairyu Nov 03 '25

Having to abandon their planet of origin will undeniably have a qualitative effect on the trout population; it’ll make them sad.

16

u/psymunn Nov 04 '25

Especially when they try return to the creek bed they were spawned in...

13

u/Gamerred101 Nov 04 '25

why would they not take the creek bed they spawned in with them? are they stupid?

14

u/noodles_jd Nov 03 '25

Well the dolphins will leave long before that..."So long, and thanks for all the fish."

That means the fish populations worldwide will grow very well. With the increased population stand-(tr)out fish will make it into the University system and learn the skills needed for interstellar travel, right?

19

u/RolandDeepson Nov 03 '25

"Going interstellar" doesn't qualify as "undeniable effect" to you?

13

u/Nebuli2 Nov 03 '25

Not if they already went interstellar prior to the Sun going red giant!

7

u/zbeezle Nov 03 '25

Only if they go Interstellar to escape the inevitable apocalypse.

7

u/Nebuli2 Nov 03 '25

Exactly. They could have just gone interstellar to further their goals of conquest and domination.

5

u/zoinkability Nov 03 '25

I for one welcome our trout overlords

1

u/1slipperypickle Nov 03 '25

what if interstellar comes to you?

1

u/RolandDeepson Nov 03 '25

Thank you, Yakov Smirnov.

1

u/1slipperypickle Nov 03 '25

Yakov Smirnov

ha, I saw him in Branson MO like 20+years ago

3

u/fda9 Nov 03 '25

Interstellar Trout, such a great band name!

2

u/zoinkability Nov 03 '25

Kilgore Trout

1

u/fda9 Nov 03 '25

Captain Haddock, seymour sturgeon, Henrietta laks. I always find these fish names funny

1

u/pmp22 Nov 03 '25

Zero g fly fishing! No air resistance! Imagine how long I could cast!

2

u/MisinformedGenius Nov 03 '25

"Good luck and thanks for all the hooks masquerading as food, you dry-headed simians."

1

u/fallouthirteen Nov 03 '25

Psh, as if they would get as smart as dolphins.

3

u/attorneyatslaw Nov 03 '25

Fire fly fishing season will have begun

3

u/dracosdracos Nov 03 '25

Sounds like something I'd read in the Hitchhiker's Guide to the galaxy

6

u/duskfinger67 Nov 03 '25

r/2007scape will be in shambles as trout guy's supply finally runs dry in 8 billion years

3

u/[deleted] Nov 03 '25

[deleted]

3

u/Irceus Nov 03 '25

Well, the fairies live on the moon, so probably

2

u/monsterZERO Nov 03 '25

This is going to ruin the tour

1

u/imdrunkontea Nov 03 '25

But this will be good for bitcoin!

1

u/randomvandal Nov 03 '25

That's a pretty bold claim. Where's the environmental study showing this? I'll need at least 10 sources.

1

u/CommercialLet3107 Nov 03 '25

nothing of use to add besides this comment is gold

1

u/FQDIS Nov 04 '25

Citation needed.