If ‘Interstellar’ Were Made Today, What Would Be Different?

IRA FLATOW: This is Science Friday. I’m Ira Flatow.

The science-fiction film Interstellar turns 10 years old this month. Hard to believe. For many of us, it was our first encounter with some pretty advanced astrophysics, taking sci-fi concepts like wormholes and time warping and backing them up with actual science.

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– We started detecting gravitational anomalies almost 50 years ago out near Saturn, a disturbance of space time.

– In a wormhole? And it leads where?

– Another galaxy.

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IRA FLATOW: Now we’re revisiting the impact that movie’s science had on pop culture and how astrophysics has advanced in the past decade. If it were made today, what would be different? Well, what better way to understand that and better person to ask than Interstellar’s science advisor, Dr. Kip Thorne? He’s also a professor of theoretical physics at Caltech, and since the film’s release, he won a Nobel Prize for his contributions for the detection of gravitational waves generated from black holes. Welcome back to Science Friday. Good to have you.

KIP THORNE: Great to be here, Ira. Thank you for inviting me.

IRA FLATOW: You were, as I say, the science advisor for the movie. Remind us how the movie came about because you played a pretty big role in that too, right?

KIP THORNE: Yes. Well, the movie began when a former girlfriend of mine, Lynda Obst, called me up and said, would you like to brainstorm with me for a movie? I had helped her and Carl Sagan a little bit with the movie Contact, on which Carl had played a role similar to mine on Interstellar in the end. And so I said, yes, of course. I thought, how better to reach a very large audience with the beauties of astrophysics than through a movie like this?

And so we brainstormed, and Steven Spielberg’s assistant came around to visit Lynda a few weeks after we started brainstorming and asked her what movies she was thinking of doing. And she described the movie we were thinking about. And he went back, talked to Steven, and Steven called her up and said, can you have a treatment on my desk by Monday? So we drew up a treatment, a very short treatment, about eight pages long, that just described the movie, the characters, and a little bit of the science in the movie.

And Steven called back and said, I would like to direct it. And I’ve never heard of a movie moving that fast. So they brought on Jonah Nolan– Jonathan Nolan, Christopher Nolan’s brother, to write the screenplay. And Jonah went through three drafts of the screenplay under the oversight of Steven Spielberg and interaction with me, a lot of brainstorming with me about additional science that went beyond what Lynda Obst and I had started with.

But then along in that process, Christopher Nolan, Jonah’s brother, said to him, if Spielberg drops out, I might be interested in directing this movie. What Chris knew was that Spielberg carries along more movies in the early creative phase than he could possibly make, and, indeed, that was the way it was, and he chose to do Lincoln.

And so after 2 and 1/2 years of Chris thinking about it but working on The Dark Knight Rises, Chris came around and said, yes, I would like to direct it. So Chris took over as director, and the first half of the movie, Jonah Nolan had almost completely changed the story from what Lynda and I began with. And the second half of the movie, Chris almost completely changed the story. So the basic outline of going through a wormhole and visiting a black hole, some of that was all already there in what Lynda and I began with, but the human story was completely changed. This really was the Nolan brothers’ movie with the science that Lynda and I began with and additional science that came out of brainstorming between me and the two Nolan brothers.

IRA FLATOW: Right. And speaking of the science, the movie has had a huge impact not just on the pop culture but on science as well. Did you hope that it would open up this mind-bending world of astrophysics to the public when you were working on it?

KIP THORNE: Well, that was my hope, yes. That was a large part of my motivation, and I feel so pleased with how effectively it did that, the number of people who have come up to me, having heard my role in this around the world and said, I decided I wanted to be a scientist from going to this movie. It’s been a huge number of young people, and it’s really been very, very satisfying.

IRA FLATOW: That has? That’s really interesting. And you were actually involved in some official research that came out of the movie, and that was the visual depiction of the black hole. You gave the visual-effects team your equations for how a black hole should behave, and you and the team published a paper on that, right?

KIP THORNE: Right, and we actually had to develop a whole new way of doing the visualizations, different from the way that they have normally been done in the past because black holes so radically distort light when the light goes near the black hole that, in order to get high-resolution images, it was necessary to use a whole new technique. Instead of propagating light rays past the black hole, we propagated light beams of finite size past the black hole, overlapping light beams. And that’s rather more complicated and a new way to do it.

And our technical paper described that and then described some of the things we discovered about gravitational lensing. That is the influence of the black hole on the light. That paper is now, I’m told, by far the most-downloaded paper in the history of the journal in which we published.

IRA FLATOW: No kidding? With what we know about black holes in the last 10 years, would that black hole look any different today? Would your equations that you fed into the computer be any different?

KIP THORNE: No they wouldn’t. We made a choice that the black hole is illuminated by a disk of gas that’s orbiting around the black hole, but it’s a thin disk, rather like Saturn’s rings. And the images you see are precisely what you would see with an IMAX camera if you were in the vicinity of that disk around the black hole.

There has been since then, of course, a scientific project called the Event Horizon Telescope that takes data from radio telescopes, a number of them scattered across the world, and combines them so that you get images that are the kind of image you would normally get from a telescope that is as big as the Earth. And with such a big telescope, you can actually– the team that has done this made images of two black holes lighted up by gas that is not in a thin disk, as we see it in the movie Interstellar, but, rather, gas that is swirling around in three dimensions around the black holes.

One of those black holes is in a nearby galaxy called M87, a giant galaxy, and the other is at the center of our own Milky Way Galaxy. Those images are a little different from what you see in Interstellar because the gas is behaving differently, but the similarity is quite striking.

IRA FLATOW: When we last talked in 2014, you said there had to be a balance between established science versus speculative science in Interstellar. Is there any speculative science in the movie that has been moving closer to established science since then?

KIP THORNE: There was a speculative science in the movie, as in the screenplay that Jonah Nolan was working on, that has moved into the mainstream of established science, and that has to do with gravitational waves. But Christopher Nolan, when he came on board, he said, look, we’re not using gravitational waves very much in this movie, and there’s so much other science that I’d like to add to the movie, and maybe we’d better just remove the gravitational wave, so he removed them.

And so when LIGO, the project I worked on that my colleagues and I got the Nobel Prize for, when it saw gravitational waves and we announced the result, I let Chris know that it was going to be announced. And the day after it was announced, Chris called me up and said, would you come over to my house? Let’s talk. So I went over, and he spent about 90 minutes describing the wonderful things he could have done with gravitational waves, if only he had kept them in the movie. And then said, well, there’s no turning back time, and so he went on to talk about the future movies.

IRA FLATOW: Did he say what he would do with them, with gravitational waves?

KIP THORNE: Not explicitly. Well, the way the gravitational waves were in the movie originally was the humans on Earth, with the LIGO gravity-wave detectors, discover gravitational waves from a neutron star that’s being torn apart by a black hole, discover those gravitational waves that have traveled through the wormhole where the mouth of the wormhole is near Saturn, the wormhole in the movie. Then Cooper and his crew travel the other direction through to get to a distant galaxy.

So the gravitational waves come through the wormhole. They’re seen. They’re observed, and it is quite startling that the source of the gravitational waves is near Saturn, and that’s how they discover the wormhole. So that’s the way it was used originally in the movie, and there are a variety of other things could have been done with it. I have forgotten what Chris was saying could have been done.

But the thing that is really interesting to me as a physicist and what I would have advocated doing with the gravitational waves in Interstellar is when two black holes collide, they actually create a storm in the fabric, in the shape of space and the storm and the rate of flow of time. So the rate of flow of time near the black hole oscillates. It speeds up and slows down in a crashing sort of way, like crashing waves in an ocean storm. The shape of space sloshes like crashing waves in an ocean storm, and it’s just fantastic how wildly space time behaves during that collision. And I would have loved to have seen that and seen how the visual-effects team dealt with that in Interstellar.

IRA FLATOW: Yeah. Let’s talk about what’s happening now with astrophysics research. What has your attention right now been now with the new black-hole science? Where’s the interesting area here?

KIP THORNE: Well, the remarkable thing is that now gravitational waves have now been seen by LIGO from about approximately 300 collisions of black holes. The gravity-wave detectors have become more and more sophisticated and more and more sensitive thanks, in part, to introducing what is called quantum precision measurement. It’s a cousin, basically, of quantum computing and quantum cryptography. Anyway, so the key thing then is that with this new technology, we’ve taken off and are seeing so many more black-hole collisions than we could see before.

In addition, gravitational waves have been discovered by a whole different technique. They’ve been discovered by radio astronomers who are looking at radio waves from pulsars. Pulsars are sort of like clocks, and they have a ticking that is associated with the spin of a neutron star. And, therefore, gravity waves passes across the Earth. It may speed up or slow down those signals by influencing the radio signals as they’re passing over the Earth, influencing, basically, the rate of flow of time of the clocks we use on Earth. So it’s sort of like radio astronomy and optical astronomy. So it’s really quite marvelous that we now have two different frequency bands for observing gravitational waves.

IRA FLATOW: Now, we talk about black holes so far away, and what about the black hole at the center of our Milky Way? Have we lost interest in that, or is there still interest in it?

KIP THORNE: Oh, that’s a very interesting black hole. What I want there is to see a movie of the flow of gas around that black hole because the process by which the black hole interacts with the gas around it we think, involves magnetic fields that thread through the black hole. And as the black hole spins, it whirls the magnetic fields around. As they whirl around, they generate electric fields that accelerate particles to very high speeds. And I would like to be able to observe a movie of this flow of gas around the black hole and, through that movie, begin to observe this fantastic process. And, in fact, the Event Horizon Telescope team is in the process of trying to make those kinds of movies, and I expect we’re only a few years away from having them.

IRA FLATOW: This is Science Friday from WNYC Studios.

You’ve said movie at least three times in this last sentence.

[LAUGHTER]

Have you been bitten by the movie bug? I mean, you’ve been a science advisor for Carl Sagan’s Contact and other Christopher Nolan films. Are you going to keep doing that kind of work? I mean, any projects you’re excited about?

KIP THORNE: Well, I had another Hollywood movie that I was working on that was conceived by Lynda Obst, my dear Hollywood friend, Stephen Hawking, and me, the three of us together. About 15 years ago we conceived it. It has never gotten fully off the ground, and, tragically, Lynda died a few weeks ago, and there was a huge loss in Hollywood, her death. And I suspect that movie may never, in the end, get made. If it doesn’t get made, maybe I’ll try turning it into a novel. It may still take off.

But on the other hand, I’m in my mid-80s. I am enjoying doing different kinds of things, such as the movies, but I’ve not ever tried to write a novel yet. And so, yeah, that would be what I might do with this.

IRA FLATOW: Tell me how the fame from these movies has affected your career, besides thinking about being a novelist now?

KIP THORNE: Well, it means that I get several requests to lecture somewhere or online a day, and I say no to almost all of them, and that’s how it’s affected my life. I’m very self-protective. I love the creative process. I just published with a wonderful painter, Lia Halloran, about a year ago a book of her paintings and my poetry. And so I’m just having a great fun being creative in ways that I never imagined I’d be creative.

I realize that the whole purpose of the Nobel Prize, from the point of view of the Nobel Committee, is to create icons who can promote science. And so, as an icon, I feel uncomfortable as an icon, but I have sort of come to terms with it. I feel some obligation to help promote science but only to the extent that it doesn’t get seriously in the way of continuing to do creative work but of new types.

IRA FLATOW: Do you think science needs a little more promotion now that it seems to be under attack in many fields?

KIP THORNE: Yes. This is a particularly scary time, I think, when we see a man being pushed to become the secretary of health and human services who promotes the idea that vaccines are dangerous when the science says that’s simply not true. It’s really a scary time for the human race and for the dangers that can come as a result of not paying attention to science. So, yes, I worry a lot about that in this era.

IRA FLATOW: Well, I’m glad you’re not worrying too much to talk with us and to be optimistic about the future. It sounds like you still are.

KIP THORNE: I am. I am.

IRA FLATOW: Yeah. Dr. Thorne, Thank you for your work, for your career, and everything you’ve given us, and we hope to have you back on the show not quite 10 years from now again.

KIP THORNE: OK, well, thank you, and try to remember to call me Kip.

IRA FLATOW: OK, Kip.

KIP THORNE: Thank you, Ira.

IRA FLATOW: You’re welcome. Dr. Kip Thorne, professor of theoretical physics at Caltech.

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