I honestly don’t have a good answer for that. I can say that the rotation affects the structure of spacetime in the vicinity, “dragging” nearby objects in the direction of the rotation like a whirlpool. There’s a certain region near the black hole where it’s actually impossible to remain “at rest” relative to the black hole, but you can enter and leave this region at will so long as you are moving in the same direction as the rotation of the black hole.
So the rotation has a profound effect on how nearby objects behave. But beyond that, I don’t have a good answer; it just seems to be how the math comes out. I’ll have to think on it further.
The simple answer that is “close enough” is frame dragging. As it rotates, it drags space around it, and if you are in that space, you are dragged along with it. This gives extra velocity if you are orbiting along with the spin.
Of course, if you try to orbit in the opposite direction than the spin, then your innermost stable circular orbit is going to be further from the black hole.
I only say the movie once, and didn’t pay too close attention to it, as I figured it would annoy me, but they must have had some sort of magictech propulsion to have matched orbits with that planet, much less leaving it and climbing back up out of the BH’s gravity well.
With whatever type of propulsion that they had to reach, land on, and leave the planet, they could have gotten the same sort of time dilation simply by flying out one way, then coming back.
I assume that it is intentional that a Cheela is also a type of pancake.
Still a pretty impressive engineering feat. Then of course, they wouldn’t be stable outside their home, and have to bring along black holes, tricky proposition that.
Drop a micro black hole into Earth, and chances are it evaporates faster than it grows. Drop a micro black hole into a neutron star, and now it’s a black hole.
Not sure how landing on a new neutron star works out for them. Or what range of gravities they can handle. Sure, it doesn’t seem like the difference between 67 billion G’s and say 90 G’s is that much, until you realize that it’s a difference of 23 billion G’s.
The “life” couldn’t be corporeal because it would be crushed out of existence. It would have to be some kind of pure energy “feeding” on the enormous magnetic field generated by the neutron star. I mean, what else is there that it could possibly be “eating”?
If it were relying on chemical bonds and other electromagnetic interactions, certainly.
But in this case, it was not, it was based on much stronger nuclear forces.
The difference in temperature of a millimeter on a neutron star would be, let me do the math real quick, a whole lot.
Keep in mind that this is a work of fiction that employs forces that we do not yet understand all that well. They probably don’t work that way, but I’m not sure we know that they don’t, and given the time of the writing of the novel, they would have known even less.
As an aside, the wormhole special effects in Interstellar were literally the first accurate visualization ever made of a wormhole. They got Kip Thorne, the world’s top expert on wormholes and probably the greatest physicist of our time, as a science advisor, and it turns out that Hollywood special effects guys have some really good computer programs for raytracing through a given set of equations. They ran Thorne’s equations through their programs and asked him “did we get it right?”, and his answer was “Wow, let me take a look at that code”.