If you want to learn about the science behind a blockbuster movie like "Interstellar," astrophysicist Neil deGrasse Tyson is your man.
Tyson's the one who pointed out that the constellations were all wrong in the "Titanic" — which shamed director James Cameron into fixing the stars for the movie's re-release in 3-D. Tyson's the one who tweeted out a series of "Mysteries of 'Gravity'" fact-checkers that turned into a Twitter sensation last year.
So you'd expect the host of "Cosmos: A Spacetime Odyssey" to be liberally sharing his opinions about "Interstellar," a movie that tweaks the space-time continuum so radically that it has critics like The New Yorker's David Denby and scientists like Bad Astronomy's Phil Plait scratching their heads. Right?
Well, not exactly.
"I don't generally offer opinions on things," Tyson, who's the director of New York's Hayden Planetarium, told NBC News. "I don't care if anybody else shares my opinion. I'm not looking for validation. As an educator and a scientist ... I will highlight things that the audience can look for."
So what should the audience look for in "Interstellar," science-wise? We'll try to keep the spoilers at a minimum, but it's not much of a spoiler to start out by saying that the movie involves black holes, relativistic time dilation and extradimensional physics. Here are Tyson's takes on those topics:
One of Tyson's books, "Death by Black Hole," touches on what space travelers would experience as they approached a black hole — and Tyson liked the way "Interstellar" put that experience on the big screen.
"When you approach a black hole, the black hole is distorting space in its vicinity, and this was captured beautifully," Tyson said. "I enjoyed watching the surrounding imagery get distorted. ... It's a sophisticated ray-tracing problem, and if you're a movie producer and you can get it right, then why not?"
The black hole scenes reminded Tyson of "2001: A Space Odyssey."
"At the time of '2001,' the mathematical formulation of black holes was not fully explored, so all they could do was play with the space and time dimension without being anchored to actual gravitational physics," he said. In contrast, "Interstellar" benefited from the calculations worked out by Caltech theoretical physicist Kip Thorne, who was one of the film's executive producers.
Thorne is also the author of "The Science of 'Interstellar,'" a movie companion book that earned a thumbs-up from Tyson. "I find it immensely readable, and very friendly to the uninitiated," he said.
Time and tides
The movie also works out some of the implications of living near a black hole. For example, general relativity dictates that time would seem to pass more slowly in the presence of a stronger gravitational field, compared to the passage of time where gravity holds less sway.
Relativistic time dilation figures prominently in the movie's plot. "Time is a resource," one character says, and it's not to be wasted. Each hour that the away team spends on one of the planets near the massive black hole in "Interstellar" translates into seven years on Earth.
That same planet had an ocean with monstrously high waves, which Tyson said was meant to be an effect produced by the black hole's strong gravitational pull. "That was not 'Let's just throw in a wave,'" Tyson said. "There was an orbital physics motivation to make that happen."
Plait and others have questioned whether planets could even survive as close to a black hole as they seem to be in the movie — or whether there could be anything like a sunny day on such planets. Tyson said the worlds could plausibly be illuminated by the glow of a black hole's accretion disk. But in any case, he's not sweating the details this time around.
"I'm a big fan of Mark Twain's saying: 'Get your facts first, and then you can distort them as much as you please,'" Tyson said.
The trippiest part of "Interstellar" comes toward the end, when the action takes place inside a black hole's event horizon. As far as theorists know, the laws of physics break down in that environment — but the filmmakers have set up what they call a "tesseract," or a three-dimensional representation of what the cosmos might look like in extra dimensions.
Inside the tesseract, it's possible to move through time as if it were a spatial dimension. "How you portray that, we don't know, so you let the producers and visual artists figure something out," Tyson said. "It's an attempt to show a person who is no longer bound into the present, a person who has access to the timeline of your own life the same way you can move around in space."
The idea is explored in Kurt Vonnegut's novel "Slaughterhouse-Five," in which aliens known as the Tralfamadorians see all moments of time as existing simultaneously. Tyson can't recall any previous attempt to illustrate the concept at the movies, however.
"I applaud their effort to try to capture that," Tyson said. "But if you had actual access to the past, then just write a note and stick it on the shelf, saying, 'Hey, I'm right here.'"
Scientists in the movies
One of the things that Tyson appreciates the most about "Interstellar" is that the scientists are the stars. Five Oscar winners have roles in the movie, and all of them portray astronauts, engineers or scientists.
"So I know the times are different from the days of the B-movies in the 1950s, where the scientist was the person you didn't want to be," Tyson said. "They were a little crazy, and they were wire-haired and they wore lab coats and stood with their test tubes, and you went to them only to get the answer to some question that you needed."
"Interstellar" shows scientists as human beings, capable of quoting Dylan Thomas as well as solving gravity (whatever that means). If you look beyond all the special effects and chalkboard equations, you'll find that the movie tells the story of family members who are knit together across space and time.
"It's about husbands and wives, sons and daughters and grandparents," Tyson said. "There's very strong relationship-building in this film, and they're all scientists. It's evidence that somebody recognizes that scientists are people, too."
Tyson will discuss "Interstellar" with the film's director, Christopher Nolan, on an upcoming episode of "Star Talk Radio." For more about black holes, wormholes and interstellar flight, check out this relatively spoiler-free story about "Interstellar" science. Puzzled by some of the film's finer points? Screen Rant provides explanations that are chock full of spoilers. What would the black hole in our own galaxy look like up close? Researchers at the University of Arizona have created their own visualization.