As you may be aware, there’s a hot new space movie now in theaters — Interstellar. Here’s the premise: It’s just a little bit in the future, conditions have become pretty horrible on Earth and some astronauts head out in search of a new planet for humans to inhabit.
Astrophysicist Neil deGrasse Tyson has been tweeting about the science behind Interstellar. In an interview with NPR’s David Greene, Tyson goes beyond those tweets, deep into wormholes, relativity and even some spoilers. Here’s the non-spoiler version of what he had to say. To find out what Tyson thinks about the plausibility of the film’s ending, click the audio link at the bottom of the page.
On wormholes, which the astronauts travel through in search of a habitable planet
A wormhole … is a science fiction writer’s favorite way to get from one place to another because you get to bypass the speed limit imposed by the speed of light: 186,000 miles per second. And that’s really fast for anything we would normally encounter in everyday life, but if you want to cross the galaxy, you would be long dead before you got there.
And so a wormhole is a literal and figurative shortcut through the fabric of space. And you take your destination, wherever it is, warp the space between you and it. You bend it back on itself and then you cut a hole out of your dimension, through a higher dimension and reappear in the dimension you just left.
It’s like taking a sheet of paper and you want to get from one edge to another. But fold it over, and then you can bring the top part of the paper as close as you want to the bottom part of the paper, but you have to leave the paper to make that transition.
The math and the physics of it is sound; it’s derived from Einstein’s special theory of relativity. But we don’t know how to make one, and even if we did make one, the equations show that they’re unstable and they would collapse upon you if you tried to go through. So, that’s where the science fiction comes in.
On the film’s representation of relativity, which involves time slowing down for the astronaut explorers as compared to time on Earth
You can run the equations of general relativity and, when you run those equations, what you learn is that if you are in the presence of a strong gravity, you will have noticeable effects on how slow your time ticks, relative to anybody else who is looking at you from the outside.
And their ratio of how slowly they aged versus everybody else was extreme. You can find strength of gravity strong enough to equal what that difference in time ticking rates would be — you could find one and it is extreme. But they made it clear this is a planet orbiting a black hole. So, there it is. It’s a time dilation effect, it’s called — and this is real, by the way. …
Our GPS satellites are farther away from Earth’s center of gravity than we are. We are deeper in the Earth’s gravitational well than are the satellites — that’s the inverse way of saying that. So time ticks more slowly for us than the GPS satellites and the designers of the GPS satellites knew this. And so the time that they send to us, to all of our devices, [is] pre-corrected for the effects of general relativity so that we, on Earth, in a different time dilated place, will have the correct time for our world.