Interstellar : 2 scienc-y questions

[cantab]

Indeed. IIRC as you descend through the Earth the gravity is roughly constant through the mantle, actually peaks at the core/mantle boundary, then sharply drops through the core.

[NERVAfan]

1) No. It's something of a plot hole that they needed the big rocket to launch from Earth but could then use the shuttle alone to launch from the target planets. The best explanation I can come up with is that the shuttle has hyper-efficient engines but nonetheless needed to reach LEO fully fuelled, and the big rocket was the booster NASA had available to do that.

Or the shuttle used something like a gas-core nuclear rocket or nuclear-salt-water-rocket that wouldn't be allowed to launch from Earth...

[magnemoe]

In the sense that you can orbit. The velocities would be HUGE though.

Only if you get close or the black hole is very large, take a black hole with the mass of the sun, here orbital speeds would be just like in our solar system.

Yes orbital speed close is large, just as around other massive bodies, try to do an science close to sun reading in KSP and watch the orbital speed.

[Bill Phil]

Only if you get close or the black hole is very large, take a black hole with the mass of the sun, here orbital speeds would be just like in our solar system.

Yes orbital speed close is large, just as around other massive bodies, try to do an science close to sun reading in KSP and watch the orbital speed.

Yes, if the black hole had one solar mass, it would be the same. The black hole here, Gargantua, is more than one solar mass by at least a few orders of magnitude. Plus, orbital speeds wouldn't be "just" like our solar system, they would be more uniform.

Btw, any object compressed can be a black hole...

[cantab]

Or the shuttle used something like a gas-core nuclear rocket or nuclear-salt-water-rocket that wouldn't be allowed to launch from Earth...

A fair point, although they then happily land it right at the potential colony sites...

[lajoswinkler]

Regarding that wormhole question: first things first, a wormhole is a hypothetical construct. While possible under the known laws of physics, the scientific community has no real evidence that any exist anywhere. Thus we can only speculate as to its properties.

That said, almost certainly a wormhole should be movable through the universe like everything else, including a black hole. Unlike in video games (and bad sci-fi movies), the universe does not have any absolute coordinate system and thus no way for any entity to be "anchored" immovably in space. In order to move it, all you need to do is move yourself the other way and then claim that you are the reference point. More practically, we don't have an obvious means of making a wormhole move, but once we start making them I presume we'll figure it out. Probably it'll involve a strong magnetic field or something of the like to hold it within a solid container or frame, which can then be carried aboard a spacecraft.

and @ Bill: that all depends on your altitude. Just like orbiting Kerbin in a high orbit involves a lower velocity, so too does orbiting a black hole. Orbiting near the event horizon would require a huge velocity, but orbiting at a million miles away isn't anything spectacular.

So the wormhole in the movie was orbiting Saturn? Because I was puzzled by "it's near Saturn". Saturn moves around the Sun.

In the universe of unknown/impossible fixed reference points, all this made me puzzled.

[problemecium]

Yeah, it was probably orbiting Saturn or one of its moons, or at least on some sort of trajectory that kept it near Saturn for a while.

[SpaceXray]

Haha yeah that question always interested me whether wormholes would magically move along the reference body, or in reality they should stay fixed in the universe and the Earth would spin and move away from it.

Perhaps the realistic, Nolan wormholes actually can orbit something since they are space-time distortions and technically might have something you might call "mass" or gravitational pull since it was possible to orbit one even.