How does the high gravity on Miller's planet create big waves?

Question

In Interstellar the gravity on Millers planet was about 130% of earth's gravity, which made everything heavy.

Shouldn't the waves be low, fast and heavy as well?

Answer 1

The slightly larger gravity on Miller's planet doesn't necessarily drag the waves down into smaller waves. In fact the waves were actually caused by an external force, namely the planet's very close proximity to the supermassive black hole Gargantua. Physicist Kip Thorne, who co-produced and advised the movie, has elaborated on that a bit in his book The Science of Interstellar. Basically the huge waves are not actual tides as they're caused on earth here by its moon, but are created a bit more indirectly by Gargantua's tidal gravitational forces.

First of all, the planet is so close to the black hole that its tidal gravitation would practically rip it apart if it would rotate around its own axis relative to Gargantua. Therefore the planet just revolves around Gargantua, always showing the same side towards the black hole:

Being so close to Gargantua [...] Miller's planet is subjected to enormous tidal gravity, so close that Gargantua's tidal forces almost tear the planet apart. Almost, but not quite. Instead, they simply deform the planet. [...] It bulges strongly toward and away from Gargantua. [...] If Miller's planet were to rotate relative to Gargantua [...], then as seen by the planet, the tidal forces would rotate. [...] The mantle would be pulverized, and then friction would heat it and melt it, making the whole planet red hot.

Yet the huge tidal gravitation of the black hole causes the planet to "rock" back and forth just slightly, which in turn causes those regular huge waves inside the water that surrounds its very surface:

What could possibly produce the two gigantic water waves [...]? I searched for a while, did various calculations with the laws of physics, and found two possible answers for my science interpretation of the movie. Both answers require that the planet be not quite locked to Gargantua. Instead it must rock back and forth relative to Gargantua by a small amount. [...] When I computed the period of this rocking [...] I got a joyous answer. About an hour. The same as the observed time between giant waves, a time chosen by Chris without knowing about my science interpretation.

The first explanation for the giant waves [...] is a sloshing of the planet's oceans as the planet rocks under the influence of Gargantua's tidal gravity [...] My second explanation is tsunamis. As Miller's planet rocks, Gargantua's tidal forces may not pulverize its crust, but the do deform the crust first this way and then that, once an hour, and those deformations could easily produce gigantic earthquakes (or "millerquakes", I suppose we should call them). And those millerquakes could generate tsunamis on the planet's oceans...