What Are the Scientific Explanations Behind Interstellar's Plot Points?

[rysezhae]

Hello everyone! I recently watched the new Interstellar movie, and have some questions that I would like answered. Warning: Spolier Alert! My questions will contain spoilers, so if you haven't seen the movie yet, and plan to do so, leave now. Also, if you are going to rant about the movie, do it somewhere else. I don't care about your opinions.

If you don't know the premise here it is: Humanity has discovered a wormhole in our system, and decide to travel through it and find a new planet due to the Earth not being able to support us anymore.

The questions:

1. After traveling through the wormhole, the first planet visited is orbiting a black hole. Because of this, time is affected; one hour on the planet = seven years on Earth. How can gravity affect time?

2. Scientists at NASA state that wormholes are not naturally occurring. So I can only assume they are artificial. If this is true, how can a wormhole be generated?

Major Spoiler!




In the end it is revealed that a future version of humanity generated the wormhole, and that we have transcended space and time. The movie states we have reached the fifth dimension. What is the fifth dimension? And how would we reach it?

 

[phinds]

1. After traveling through the wormhole, the first planet visited is orbiting a black hole. Because of this, time is affected; one hour on the planet = seven years on Earth. How can gravity affect time?

Space-time is "curved" by gravity and this naturally results in time dilation of an object in a gravity well as measured by an observer far outside that well. The specific example given in the movie would require a gravitational force that would VERY quickly cause the planet to spiral into the BH, so the physics of gravitational time dilation is real and the movie is nonsense.

2. Scientists at NASA state that wormholes are not naturally occurring. So I can only assume they are artificial. If this is true, how can a wormhole be generated?

Theoretically a wormhole can (MAYBE) be generated by the magical creation of "exotic matter" which is not believed to exist. The movie's use of science is just a spewing of scientific words. As has been noted in another thread about the movie, here on this forum, Kip Thorne should be ashamed of himself for allowing his name to be used on it. BUT ... he's clearly not. I saw an interview with him were he cheerfully admits that the wormhole stuff in the movie is completely unlikely but he justifies it by virtue of the fact that it is possible in theory even though no one seriously believes that it could ever be done in practice.

In the end it is revealed that a future version of humanity generated the wormhole, and that we have transcended space and time. The movie states we have reached the fifth dimension. What is the fifth dimension? And how would we reach it?

It's nonsense. This is a movie, not science.

 

[Fredrik]

1. After traveling through the wormhole, the first planet visited is orbiting a black hole. Because of this, time is affected; one hour on the planet = seven years on Earth. How can gravity affect time?

General relativity tells us that it does, and by how much. It doesn't tell us how it's possible. To ask this question, is to ask why general relativity is a good theory. The only thing that can answer that is a better theory. Unfortunately we don't have one...and if we did, you'd probably be asking how that theory's claims are possible.

I don't know how plausible the "one hour = seven years" scenario is. I know that it's possible in principle if you descend straight down, hover for a while, and then fly back up. But realistically, the engines wouldn't be strong enough, and there wouldn't be enough fuel. Even if we solve that by magic, the thrust from the engines would break the ship to pieces, because the ship is accelerating in an insane way to stay at a fixed altitude. (Yes, general relativity is weird). If we also solve that problem by magic, the people inside the ship would still be crushed against the floor.

However, they didn't descend straight down. They matched the trajectory of an object in orbit. This changes things a lot, and I don't know how. So I can't say that this time dilation effect is realistic, but I also can't rule it out. I don't know what the fuel requirements would be, or if there would still be crushing forces involved. I suspect that the scenario won't hold up to closer inspection, but it's complicated to work it out.

There are other issues. Was that just a planet in orbit of the black hole, or an entire solar system? If it's the entire solar system, then I'm not so sure it could be stable. If it's just the planet, then they could have immediately concluded that the planet is dead.

2. Scientists at NASA state that wormholes are not naturally occurring. So I can only assume they are artificial. If this is true, how can a wormhole be generated?

It's probably not possible. At the very least, it would require mass production of a type of matter that has never been observed in any experiments so far. Even if we could do that, it's possible that quantum gravity would prevent the formation of large stable wormholes.

The movie states we have reached the fifth dimension. What is the fifth dimension? And how would we reach it?

Spacetime is 4-dimensional in these sense that it takes 4 numbers to identify a point in it (an event). The idea in the movie appers to be that our spacetime is a 4-dimensional slice of something 5-dimensional, or 11-dimensional or whatever, and that "they" have a fundamentally different experience of that larger structure, and therefore a fundamentally different experience of space and time. This idea is probably inspired by string theory, but I don't think there's anything in string theory or any other part of physics that suggests that such beings could exist. Even if I knew that something like that exists, I would find the idea that we can "get there" absurd. It would be like Pac-Man becoming human.