Pete Cortez said:
Indeed, but unless one of those observers has a relativistic rocket on hand that's not going to be the case. It certainly won't be the case for Miller's planet and the shell of fire.
I'm afraid I don't know what you are saying here, are you claiming there is something magical about a circular orbit, compared with all the other possible orbits that would cross a circular orbit at relativistic speeds, such that the circular orbit is the one that does not see redshifts and blueshifts? Because that's just not going to be right.
If you're hovering. If you're falling free, the answer is you'll see no shift compared to when you started at infinity.
Are you now assuming that your "free fall" orbit includes infinity? Because circular orbits don't. Miller's planet will cross at a relativistic speed any orbit that involves falling free from infinity, so you cannot have it both ways here-- one or the other will see dramatic Doppler shifts. I suspect both will, but I'm sure the circular orbits will.
Neither Miller's planet nor the disk are hovering. They are in free fall, and they did not arrive with absurdly high relativistic base velocities.
Again, you need to stop imagining that "free fall" is some special state of existence. Various different free-fall orbits will have highly relativistic relative speeds at the points where they cross.
Not sure what an "approach orbit" is, but why would you free falling observer to see Gargantua's light red or blue shift depending on the height of the orbit?
By "approach orbit", I just meant "not the circular orbit of Miller's planet." It is perfectly obvious that observers falling free from infinity will see the light from an accretion disk that is either redshifted or blueshifted. For example, when they start their free-fall at infinity, they will see substantial gravitational redshift, and essentially no blueshift. When they arrive, in their free-fall, at the disk, they will have significant relative speed to the disk, so will see blueshifts. All these shifts will also depend on direction. A difficult calculation, I would never attempt it-- but I didn't just do a nearly-petabyte ray-tracing calculation either. But once the decision was made to alter the appearance of Gargantua for dramatic reasons, I suppose it became less of a priority to make
anything about it look right, other than the gravitational lensing.
Upwards 7 AU, actually. And they did worry about how the Ranger could arrive without sustaining deadly g forces. Gravitational slingshots around sufficiently massive objects. This is a supermassive black hole system. Think more in terms of the center of the galaxy rather than a star system. There's at least one neutron star in the vicinity. Space could be littered with other stars, intermediate black holes, and the like.
Well, I won't beat them up about this, because sci-fi always needs to do impossible things to have a story, but note that the Ranger did not have any particular launch window for getting back to the Endeavor, so we can hardly claim they are going to be using gravitational assists from random orbiting flotsam. Still, if their picture is that the Endeavor is orbiting some 7 AU away, and they are managing to dart around the relativistic orbits of the various planets by gravitational assists, perhaps by dropping into the ergosphere and drawing on the Penrose effect, then I'm not going to sweat it-- that's their picture, and that's fine. But the light should still look Doppler shifted.