Finding our place among the stars

![Figure][1] ![Figure][1] The blockbuster film Interstellar is a stirring defense of space exploration and of our trust in science to get humanity out of trouble. This ambitious movie weaves complex ideas from physics—including relativity, quantum gravity, and higher-dimensional space—into the very fabric of its narrative. With a running time of just under 3 hours, the film manages to tell a gripping story while still getting most of its science right. Interstellar is set in a near future when blight has destroyed most of the world's crops and food is becoming scarce. The human population has declined precipitously, and humans are in danger of dying out within a generation or two. But a ray of hope comes from space. A wormhole has appeared near Saturn, and a small group of NASA scientists plan to use it to find habitable planets that could serve as humanity's next home. Wormholes are not new to science fiction, and although there is no scientific evidence that they exist, they are rooted in various solutions to Einstein's theory of general relativity. They also conveniently solve the science fiction author's problem of how to transport characters across vast interstellar—or intergalactic— distances in a relatively short time. The accuracy of science in the film owes much to one of its executive producers, theoretical physicist Kip Thorne, who has coauthored technical papers on the possibility of traversable wormholes ([ 1 ][2], [ 2 ][3]). But credit must also go to director Christopher Nolan, who was committed to maintaining a scientifically plausible story line. One example of this collaboration is described in Thorne's wonderfully entertaining companion book The Science of Interstellar. It arose when Nolan informed Thorne that the plot required a planet where 1 hour spent on the surface would equal 7 years on Earth. This, according to Nolan, was “non-negotiable.” While at first skeptical, Thorne ultimately calculated that such a planet could theoretically exist if it were orbiting close enough to a supermassive black hole that was rotating close to the maximum speed allowed by physics. Whether moving humanity to this world is a good idea or not is a separate question, but science allows the possibility for such a planet to exist. ![Figure][1] PHOTO CREDIT: © PARAMOUNT PICTURES CORPORATION Although wormholes are still in the realm of theory and speculation, supermassive black holes do exist and are often found at the centers of galaxies. In chapters 8 and 9, Thorne describes the science that inspired the visual depiction of the black hole in the film. Recalling the first time he saw the film's black hole—Gargantua—he writes, “What a joy it was when I first saw these images! For the first time ever, in a Hollywood movie, a black hole and its disk depicted as we humans will really see them when we've mastered interstellar travel.” The results are spectacular to behold in the movie, and Thorne informs the reader that the models and simulations that helped inspire the images will serve as data in one or more forthcoming technical papers. One of the best features of the book is its coding system for chapters and subsections into “T” for truth, “EG” for educated guess, and “S” for speculation. For example, much of Gargantua's anatomy is based on broadly accepted theories in physics and, as such, this section is labeled with a “T.” The visualization of what one might see inside the black hole, however, is firmly speculative and labeled with an “S.” Clearly, the movie is based in good science; however, it is not without its issues. For example, it decidedly lacks a sense of wonder and curiosity that one would expect to see in a story about exploring new worlds. Similarly, in the imagined future of the film, there seems to be a noticeable lack of internationalism. American flags are fluttering on planets in another galaxy, and baseball seems to be the sport of choice even in orbital colonies. This is all the more surprising because the movie itself is a result of an international collaboration. Although Interstellar does not have the philosophical sophistication of 2001: A Space Odyssey , it is still a unique and ambitious film that does not shy away from complex sociological and scientific ideas. Despite its grim premise, the film's message is ultimately one of faith in science and human ingenuity. As agricultural insecurity and resource scarcity become realities in our own 21st-century world, I can't help but hope that the film's main character is right when he states, “We are going to find the way—we always have.” 1. [↵][4] 1. M. S. Morris, 2. K. Thorne , Am. J. Phys. 56, 395 (1988). [OpenUrl][5][Web of Science][6] 2. [↵][7] 1. M. S. Morris, 2. K. S. Thorne, 3. U. Yurtsever , Phys. Rev. Lett. 61, 1446 (1988). 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