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News notice: The Seventh AIP Early-Career Conference for Historians of the Physical Sciences will take place June 21–25, 2027, in Toronto, Canada. The call for papers will be open through November 15, 2026. The conference welcomes submissions from around the globe, and supplementary travel funds will be available. For instructions and further details, see the page for the conference on the AIP website.

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Harvard University historian Peter Galison’s 2021 animated short film Shattering Stars depicts a famous and fateful 1935 confrontation between two astrophysicists: the youthful Subrahmanyan Chandrasekhar and the eminent Arthur Eddington. The film’s story is built around audio excerpts from an oral history interview that AIP historian Spencer Weart conducted with Chandrasekhar in 1977, and Galison has kindly answered several questions for us about how he adapted the material.

Shattering Stars can be viewed in its entirety on Aeon magazine’s YouTube channel.

Will Thomas: How did you first come across Spencer Weart’s interview and how did you decide it would be a good subject for a film?

Peter Galison: In 2015, Andy Strominger, Shep Doeleman, Avi Loeb, Ramesh Narayan, Shing-Tung Yau, and I began planning an interdisciplinary center for the study of black holes. No other object in the sky draws together such diverse disciplines; there are no philosophical or mathematical subfields dedicated to neutron stars. Quickly I was drawn into the Event Horizon Telescope Collaboration (EHTC) which formed that year, with the target of imaging a black hole. Alongside the science, I began filming The Edge of All We Know (Netflix, 2020), which tracked the collaboration through its release. It was this work that led to the making of the film, during Covid home-boundedness. The topic: a decisive moment in the history of black holes.

In 1930, 19-year-old Subrahmanyan Chandrasekhar boarded a ship for Cambridge, England to work with the world’s most famous astronomer, Arthur Eddington. On the voyage, Chandra had a remarkable insight. By combining the then-new quantum mechanics with gravity, he showed that burned-out stars (white dwarfs), if massive enough, could continue to collapse seemingly without limit. Eddington first promoted and then, at the 11 January 1935 Royal Astronomical Society meeting, denounced Chandra’s work as nonsense, upending the young scientist’s life. I wanted to make an animated film about that turning point.

I’ve been coming to the AIP since I was an undergraduate, when the institute stood near the United Nations. Spencer Weart, director of the Center for the History of Physics, was assembling audiotaped interviews, building on Thomas Kuhn’s earlier quantum interviews. I had used some of those oral history interviews and had conducted others.

When I heard the Chandrasekhar interview tape, there was no question about its importance for the film—it shifted the film toward a first-person view: Chandra’s. I found his tone utterly unexpected. Not the triumphant overcoming-adversity story that one might expect. Nor the vindication of the 1983 Nobel Prize. No, Chandra had a measured, wistful affect, the pain of betrayal by Eddington still audible after 42 years. Twice, Chandrasekhar called the moment “shattering,” and I knew that term would figure both in the title and the film’s bookended opening and closing, Shattering Stars.

Shattering Stars was to be neither a biography nor a debate. Instead, I aimed for a first-person recollection of a traumatic moment in physics. 1935 was a time when the nature of the black hole was in doubt—for years, Einstein feared that the Schwarzschild solution indicated that the general theory of relativity might fall apart if the radius equaled twice the black hole mass: the term in the Schwarzschild metric 1/(1- 2M/r) looked like it would blow up at r = 2M. Adding to the unease of the time: these were waning years of the British Empire, two years into Hitler’s terror, and in the run-up toward Indian Independence.

Thomas: AIP’s audio tape of this interview is somewhat degraded, but you’ve turned it into something really striking. Can you tell us about how you got the sound repaired and about the creative partnerships, particularly with animator Shiv Kachiwala, that brought the excerpts to life?

Galison: My longtime and brilliant editor, Chyld King and I had worked together for some fifteen years. Filmmaker Robb Moss and I co-directed and produced Secrecy (2008) and Containment (2015), both of which Chyld edited. Around 2015, Robb began filming the third of his first-person trilogy about his river-rafting circle of friends across half a century. That was, as I mentioned, when I joined the EHTC and, with Chyld King editing, began filming Edge. Chyld has a strong background in audio, so when we got the Chandra recording, he took on the difficult task of audio restoration. The recording itself had been made on a “compact cassette” (1/8” tape) in a recorder with a built-in mic. There was background noise and Chandra himself was sometimes near and sometimes far from the recorder, making the tape just about unusable. Emotion and vividness were there, but the recording? Awful. Back in the 1970s, the purpose of the AIP recordings was to produce printed interviews and it did that wonderfully; no one worried about other purposes.

We tried 2020 tricks of the trade: adjusting equalization, for example, but that proved frustratingly ineffective. A machine-learning-based tool (audio.ai) finally got the recording into a usable form, but the app caused collateral damage, lopping off sibilants that we had to re-stress instance by instance. Along the way, there were discouraging moments: just when we thought we’d succeeded, someone would say they could not understand Chandrasekhar. We even considered re-recording text with an actor (which we did with Eddington, since almost all BBC recordings were destroyed in the Blitz). But the texture of Chandra’s own voice won the day. We simply could not do without it.

From the start, I wanted to find an Indian animator who would have an empathetic eye in depicting Chandra in Britain. Chyld and I viewed dozens of Indian animation festival winners, and were, hands-down, keenest on the work by Shiv Kachiwala. He, too, proved a great collaborator, and his two-dimensional art style with flat, lightly-graded, muted colors was perfect. Astonishingly, Shiv has never been in the same room as Chyld and I, though throughout that Covid year we had countless Zoom calls, emails, sketch exchanges, color trials, and animated sequences. Distance never slowed us. I sent Shiv stills from classic noir films that conveyed the kind of lighting I wanted. He understood immediately. At every stage, back-and-forth: I’d send (for example) a picture of a 1930s mechanical calculator I wanted Chandra to be manipulating in a sequence, and in short order Shiv had found a way to integrate it—in his style—into the shots. Chyld, Shiv, and I constantly cut, added, swapped parts of the interview.

Thomas: I’m particularly struck by the way the more abstract sequences—like Chandrasekhar approaching a black hole on a staircase of books—convey at once the strangeness of the theoretical object, the act of theoretical research, and Chandrasekhar’s and Eddington’s personalities and emotional states. How did you come up with this kind of imagery? Did you have any particular inspirations?

Galison: From early in the filmmaking process, I decided the film needed two distinct styles of animation. One would be in the kind of two-dimensional, limited-motion style in which Shiv was an expert. I wanted colors and lines, more Hergé’s Tintin than continuous-motion Disney or Pixar. Something that evoked the 1930s, certainly not “realistic,” if by realism one has in mind the high-end animation styles of the 2020s (e.g., digital rotoscoping and CGI). In Shattering Stars the 2D visual idiom depicts actions by real people in the world: the trip from India to England; the work and life at Trinity College, Cambridge; the confrontation with Eddington at the Royal Astronomical Society. This was a world I wanted to depict, a noir movie, pools of light trapped in claustrophobic spaces. I wanted to capture life hemmed in and growing more so around Chandrasekhar and, in a broader sense, the world as it careened toward conflagration.

The second style I wanted was grounded in the blackboard reality—chalk on slate—in which theorists have worked for 150 years. That was the medium of the theorists’ imagination, the sphere of calculations and ideas. In Shattering Stars, the key (physics) ideas were a balance of radiation against gravity and Chandra’s central innovation: that pressure against radiation was limited by the brute fact of special relativity that electrons could not be accelerated beyond the speed of light. But the blackboard look also included the phantasmagoric world of Giant Eddington with book-headed people looking up in awe. That was the bifurcated world I wanted: a chalk-world of excitement, imagination, a universe greater than us. Against it: the darkening 1930s European scene, the bubble of pre-war Cambridge with walls too guarded, too high to admit Chandrasekhar and his blossoming ideas.

Thomas: Oral history interviews capture interviewees’ perspectives at a particular moment in their life. Can you comment on how Chandrasekhar’s narration captures his perspective on his encounter with Eddington in a period when he had been professionally very successful but had not yet won the Nobel Prize for his early work?

Galison: Chandrasekhar wrote book after book that laid out the principles and techniques of theoretical astrophysics. Generations of students and practitioners treated them as foundational guides to (for example) stellar structure, hydrodynamic and hydromagnetic stability, the mathematical theory of black holes. After his humiliation by Eddington, Chandra says in the film that he never again undertook the kind of radical step he had pursued in the 1930s, out into the unknown. Instead, he saw another way, one defined by rigorous, foundational studies, offering a path that others could climb with confidence that they were on solid ground. This inspired us to have the final scene with (the now older) Chandrasekhar setting down book-steps up into space, toward the black hole.

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William Thomas
American Institute of Physics
wthomas@aip.org

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