Paradigm Shifts: Epstein Drive, Eros, and Thomas Kuhn

Paradigm Shifts

Epstein Drive, Eros, and Thomas Kuhn

By Nathaniel Goldberg

“My drive would give us the edge that we needed to finally break free from Earth and build a new world for ourselves. That’s the wonderful and terrible thing about technology. It changes everything.”

“Paradigm Shift,” season 2, episode 6 of The Expanse, mixes events from the story’s present with these voice-overs by Solomon Epstein from the story’s past. The technology that Epstein is describing here came to be known as the “Epstein Drive.” It led to Mars’s independence from Earth, the colonization of the Asteroid Belt, and—eventually—the discovery of the protomolecule by Jules-Pierre Mao’s company, Protogen, on Saturn’s moon Phoebe. That led in the story’s present to the asteroid Eros’s collision course with Earth until it got redirected into Venus just in the nick of time. Like the Epstein Drive, Eros’s trajectory is the result of technology, this time the protomolecule.[1] And, like Epstein Drive, Eros changed everything.

The title of the episode, “Paradigm Shift,” comes from philosopher Thomas Kuhn’s The Structure of Scientific Revolutions.[2] Kuhn argued that certain inventions or discoveries, including new technologies, are so significant that after them “we may want to say that … scientists,” and even the rest of us, “are responding to a different world.”[3] The Epstein Drive and Eros are great examples of paradigm shifts. In a straightforward sense, the Epstein Drive let human beings respond to worlds in the Asteroid Belt by colonizing them. As explained in “Abaddon’s Gate,” season 3, episode 13, Eros would transform into the Ring Gate, letting human beings respond to up to 1,373 different worlds by traveling to them. Yet Kuhn also meant that we may want to say that new inventions, discoveries, and technologies change the world we’re already living in.

What did Kuhn mean by that? And how is it related to his notion of a paradigm shift?

Paradigm Shifts

Kuhn wrote The Structure of Scientific Revolutions to “produce a decisive transformation in the image of science by which we are now”—or, at least, were then—“possessed.”[4] That image was of science always progressing in a straight line, theories building cumulatively on one another. The image that Kuhn argued for was of science sometimes advancing by leaps and bounds, throwing out what came before and coming up with something entirely new. “Normal science,” as Kuhn called it, is linear. But science isn’t always normal. Sometimes paradigm shifts appear, which cause scientific revolutions.

So what’s a paradigm shift? Obviously, it’s a shift in paradigms! What’s a paradigm? That’s less obvious. Before Kuhn, “paradigm” meant a grammatical model, such as a verb conjunction. With Kuhn, it came to mean a scientific achievement, such as a significant invention, discovery, or exemplary application of a theory that students might train on. The Epstein Drive and Eros count as paradigms in that sense. They were a significant discovery and invention, respectively. In the postscript to Structure,Kuhn would give that sense of “paradigm” (which he renames “exemplar”)[5] priority. But Kuhn also intended “paradigm” to mean the problems, solutions, and values of a scientific community connected to its scientific achievement. He even meant an entire scientific and philosophic worldview that came about as a result.[6]

The episode “Paradigm Shift” shows that these meanings of Kuhn’s “paradigm” overlap. The Epstein Drive was a significant invention. It also presented the scientific community of its day with problems (how can the drive’s efficiency be explained and replicated?), solutions (they can be done with these theories and designs), and values (doing so requires caring about accuracy as well as safety, since Epstein didn’t survive his drive’s initial run). Finally, the Epstein Drive caused a change in worldview (the outer solar system was now within humanity’s reach).

Eros provides an even better example of the overlap in meanings. That an asteroid was suddenly on a collision course with Earth was a significant discovery, if anything was. The discovery was even more significant than that, however. Not only was Eros self-propelled. When Fred Johnson, a former U.N. marine turned leader of the Belt’s Outer Planetary Alliance (or O.P.A.), and now chief of operations of Tycho Station, loaded the colony ship The Nauvoo with nuclear weapons to change Eros’s trajectory, the asteroid swerved to avoid it. Astonishingly, Eros then continued hurtling back toward Earth. Had Detective Josephus Miller not found Jules-Pierre Mao’s daughter Julie on Eros and convinced her (or what the protomolecule had not yet disassembled of her) to redirect Eros into Venus, life on Earth would have been destroyed. Further, Eros presented scientists with problems (what was the protomolecule doing to it to it?), solutions (Earth sent The Arboghast and a Martian ship unnamed in the episode to investigate Eros after it crashed into Venus), and values (doing so may pit knowledge and political gain over safety, since crews of both ships got disassembled by the protomolecule). Eros also caused a change in worldview. Earth scientist Dr. Michael Iturbi, who later sets sail on the Arboghast to Venus to investigate what became of Eros, tells U.N. Deputy Undersecretary Chrisjen Avasarala: “I believe the Eros incident was our first contact with alien life.” Avasarla’s reply indicates just how world changing that makes it:

I have a file with 900 pages of analysis and contingency plans for war with Mars, including 14 different scenarios about what to do if they develop an unexpected new technology. My file for what to do if an advanced alien species comes calling? It’s three pages long, and it begins with, “Step one, find God.”

Eros caused an entirely new scientific and philosophic worldview, because it meant that humanity wasn’t alone in the universe. Once the Ring Gate would become operational at the end of season 3, we’d be in for even more of a ride.

From Paradigms to Politics

Related to Kuhn’s take on paradigms was his point that science and politics are connected. Government and industry are major funders of scientific research, and each has its own political agendas. So the public and private sector both influence the progress that scientists make and ultimately the paradigm shifts that come about.

The Expanse illustrates Kuhn’s point really well. The United Nations, the government of Earth, is dealing with overpopulation and residual effects of climate change, all while asserting (or at least defending) military interests in the system. They’re not going to “waste” money on science unrelated to those ends. Meanwhile, the Martian Congressional Republic has two overriding goals. First, lacking the U.N.’s numbers, they want to maintain technological superiority over the U.N.’s military. Second, every Martian dreams of finishing the terraforming of Mars. The M.C.R. is going to fund scientific research connected to almost nothing else. Finally, megacorporations such as Protogen invest in things to maximize profit.[7] Not all private-sector firms are run by the likes of Jules-Pierre Mao. But a clandestine research station on Phoebe, experiments on the unsuspecting population of Eros, experiments on unsuspecting children on Jupiter’s moon Ganymede to try to create human/protomolecule hybrid super-soldiers—Protogen funds all of these because that’s where Mao thinks the money is.

Sometimes what starts off as not connected with politics, or connected only in limited ways, has far-reaching political consequences. In the real world, the internal combustion engine was a significant invention. It also led to military tanks and airplanes, which decided world wars, and to personal cars, which gave rise to suburbs. Benjamin Franklin flew his kite and made the significant discovery that lightning was a form of electricity.[8] Electricity in turn lit streets, ran devices, and made possible our own megacorporations, such as Apple, Facebook, and Google—more politically powerful than many governments.

“Paradigm Shift” does a great job of spelling out the political consequences of the Epstein Drive and Eros. By deploying three flashbacks to Epstein and then cutting to fallout from Eros, the episode also emphasizes how the two paradigm shifts are parallel.

In the first flashback, Epstein explains:

Mars had been a colony for a long time…. We were ready to govern ourselves and start a new nation of our own, but everything we built, or mined or made, was still the property of old Mother Earth…. My name’s Solomon Epstein. And I changed everything.

As we know, the Epstein Drive led to Martian independence, the colonization of the Belt, and the discovery of the protomolecule—leading to what happens with Eros. A further political consequence of the drive is that it led to a separate Belter identity. The Inyalowda, from the inner worlds of Earth and Mars, became culturally distinct from the Beltalowda, from the outer worlds of the Belt. The Epstein Drive therefore gave rise to the current political state of the solar system—Mars versus Earth, with the Belters squeezed—which Protogen exploited for profit.

After the flashback to Epstein, “Paradigm Shift” cuts to the present as top U.N. officials discuss Eros. Marine Corp Col. Janus explains: “Eros was a wake-up call. Whatever it was, it’s clearly the greatest technological leap—since the Epstein Drive.” Janus, however, couldn’t predict its political consequences. After Eros’s wake-up call, the Cold War between Mars and Earth would thaw. Once  Johnson captured 30 planet-buster nuclear missiles (powered by Epstein Drives!), the Belt would increase its political power. And Protogen would play Earth and Mars off one another at the Belt’s expense. Nuclear missiles or not, Johnson later in the episode puts his political spin on events: “Eros changed everything…. And whenever that happens, Belters always lose.”

The second flashback to Epstein isn’t as telling, but the third is. It’s the one this chapter opened with. Epstein was right. Mars did finally break free to form a new nation, the Martian Congressional Republic, standing side by side with the United Nations of Earth as both expanded into the Belt. Though Epstein couldn’t know this, the Epstein Drive also led to the discovery of the protomolecule, which would set Eros (literally) into motion.

Discovering the protomolecule would also lead to Mao’s super-soldier project, which becomes relevant after the flashback. The episode now cuts to the present as bad-ass M.C.R. Marine Bobbie Draper and her battalion patrol outside the joint U.N.-M.C.R. agricultural station on Ganymede, the clandestine site of Protogen’s child super-soldier experiments. U.N. marines appear to charge Bobby’s unit, as U.N. and M.C.R. fleets in orbit engage one another. Eventually, Bobby gets knocked out. When she comes to, she see her fellow marines dead and what viewers recognize as a human/protomolecule hybrid staring down at her. That’s the wonderful and terrible thing about technology. It changes everything.

But Does It Change Worlds?

Epstein claimed that his drive changed everything. Johnson claimed that Eros changed everything. And Kuhn claimed that we may want to say that after a paradigm shift scientists are responding to a different, and therefore changed, world. How serious were Epstein, Johnson, and Kuhn? Do paradigm shifts change everything, including worlds? And, if they do change worlds, do they change them in more than the straightforward sense that the Epstein Drive and Eros, once it transforms into the Ring Gate, let human beings live on different worlds?

Epstein can’t literally mean that everything changed after the Epstein Drive sped him off into space. Unfortunately for him, it didn’t change that he was flesh and blood. As Epstein explains, “[I]n a sustained, high-G burn, what usually kills you is a stroke.” That didn’t change either, since that’s exactly how Epstein dies. Johnson can’t literally mean that everything changed after Eros, either. Johnson claimed that the Belters always lose. That much, on his view, wouldn’t change, even if Beltalowda did start getting respect.

Can Kuhn literally mean that everything changes after a paradigm shift? There are two reasons to be cautious here too. First, unlike Epstein and Johnson, Kuhn doesn’t actually claim that everything changes. Instead, he claims that we may want to say that everything does. That’s because we may want to say that scientists are responding to a different world, even if they really aren’t. Second, Kuhn may not mean that a new invention, discovery, or technology directly causes everything to change, either. Remember, Kuhn’s notion of a paradigm is really broad. Besides things like new technologies, it also covers the problems, solutions, and values connected to them, as well as the resulting scientific and philosophic worldviews. So maybe, for Kuhn, new technologies indirectly cause everything to change, or at least we may want to say that they do.

Kuhn develops these ideas together when he writes:

Led by a new paradigm, scientists adopt new instruments and look in new places. Even more important, during revolutions scientists see new and different things when looking with familiar instruments in places they have looked before.[9]

Let’s suppose that by “paradigm” Kuhn means a significant scientific achievement, such as a significant invention or discovery. Scientists (and maybe the rest of us) then use new things when looking in new and old places. Inventions and discoveries can cause us to see the world differently. Still, those are new and old places in the same old world. The world stays the same. That would explain why, after telling us that after a paradigm shift

[i]t is rather as if the professional community had been suddenly transported to another planet where familiar objects are seen in a different light and are joined by unfamiliar ones as well,

Kuhn quickly adds: “Of course, nothing of quite that sort does occur.”[10]

So Epstein and Johnson can’t literally mean that everything changes. For his part, Kuhn never claims that it does, and even if it did it wouldn’t necessarily do so directly. Yet, contrary to all this, Kuhn also insists that “there is a sense in which [paradigms] are constitutive of nature.”[11] By “nature,” Kuhn means the natural world, the world that scientists describe, the actual world we live in. So there has to be a sense in which the world does change for Kuhn. We’d not only be able to live on different planets, but the planet—the world, the universe, etc.—which we’re already living on would change, too. Perhaps just as importantly, Kuhn’s often read as meaning that it would. That’s one reason that he was so influential. Kuhn’s view was world changing because lots of people read him as believing that paradigm shifts—literally—change worlds.

It’s not necessarily wrong to read Kuhn that way, either. That’s because the idea of changing worlds is connected to Kuhn’s idea of incommensurability.


Like “paradigm shift,” “incommensurability” is one of Kuhn’s catch-phrases. The idea of two things being incommensurable is the idea that there is no common standard to evaluate them objectively. Always needing to assume one side or the other, you can’t ever render a neutral verdict.

Kuhn’s chief example of incommensurability is between Isaac Newton’s laws of motion and Albert Einstein’s theory of relativity.[12] Newton’s laws and Einstein’s theory were both significant discoveries, and Kuhn regards them as paradigms. Here he seems to mean Newton’s and Einstein’s theories as abstractions, though he also has in mind “concrete” examples of their application that science students train on.[13] Concrete examples would make Newton’s laws and Einstein’s theory paradigms in Kuhn’s primary sense of exemplary applications of theories.

Regardless of how we understand them, Kuhn’s point is that Newton and Einstein both talk about “mass.” However, by “mass” Newton means something equaling force divided by acceleration. That follows from F = ma, his second law of motion. Newton doesn’t mean something equaling energy divided by the speed of light squared, which follows from E = mc2. That’s part of Einstein’s theory of relativity, instead. So what does “mass” really mean? Kuhn says there’s no objective answer. Rather, Newton and Einstein are talking about two different kinds of mass: “Newtonian” mass and “Einsteinian” mass. And they’re incommensurable.

But wait. Do Newtonian and Einsteinian mass interact? Where do they exist? Here’s where Kuhn’s idea of changing worlds gets its grip. Since there’s a sense in which each paradigm is constitutive of a different kind of mass, and nature generally, each kind of mass apparently exists in a different world.

“Paradigms Shifts” directly expands on Kuhn’s example. Iturbi tells Avasarala: “Suddenly, Eros, the entire asteroid, moves in a way that practically defies every single known law of physics.” This one concrete example might throw F = ma and E = mc2 out the window. There’d presumably be some other equation in play. But then there may be three kinds of mass: Newtonian, Einsteinian, and Erotic! (Weird though it reads, that would apparently be the appropriate adjective….) Science students would have to train on new exemplary applications of a new theory—maybe even ones involving Eros. Because of Eros’s inexplicable behavior, we may want to say that, after Eros, Earth, Mars, and the Belt are responding to a different world. Apparently, the world they find themselves in now obeys different physical laws.

While some people delighted in Kuhn’s idea of incommensurability and different worlds, others were horrified. To them, the idea that paradigm shifts changed worlds sounded more like sorcery than science. One response by horrified, anti-sorcery philosophers was to distinguish conception from reality.[14] Just because Newton and Einstein have, and perhaps post-Eros Earthers, Martians, and Belters would come to have, different conceptions of mass doesn’t mean that they’re referring to different things in reality. The way different people conceive of the world can differ, but there’s really only ever one world. For those philosophers, paradigm shifts should be understood in terms of changing conceptions rather than changing worlds.[15] However, like factions within the O.P.A., not every philosopher in the A.P.A. (or American Philosophical Association) agrees.

Other Paradigm Shifts

Regardless of where you stand on incommensurability and worlds, Kuhn’s idea of paradigm shifts caught on like wildfire—or like a fusion reaction inside an Epstein Drive or the protomolecule on Eros. Academics outside science and philosophy started using it. It entered everyday English. James S.A. Corey even named an episode of The Expanse after it.

Given the parallelism in “Paradigm Shift” between the Epstein Drive and Eros, the episode title almost certainly refers to them. Regardless, in closing it’s worth considering what arguably are two other—and other kinds of—paradigm shifts in the episode. We can then appreciate how just applicable Kuhn’s idea really is.

First, Eros brought an end to the story arc the series started with: Miller’s search for Julie. “Paradigm Shift” is the first episode after he finds her. Post-Eros, there’s a paradigm shift in the show’s narrative focus. And there’s a sense in which it really does feel like a different show.[16]

Second, “Paradigm Shift” is also the episode in which James Holden and Naomi Nagata come clean with Alex Kamal and Amos Burton, their crewmates on The Rocinante, about their relationship. Holden explains: “So in the interests of the smooth operations of this vessel, and the morale of this crew, I just wanted to let you know, that Naomi and I are together. Sleeping together.” The scene is played up for laughs, as Holden’s seriousness is met by Amos and Alex’s explaining that they’d already figured it out and even bet on when the relationship started. Giving Amos the win, Holden answers: “Just after we got out of Eros.” Post-Eros, there’s a paradigm shift in the crew’s romantic situation. In fact, since Miller had a crush on Julie, we might think of these two different paradigm shifts as part of a single one. In “Paradigm Shift,” the narrative-romantic paradigm shifts from Julie and Miller to Naomi and Holden.

The usefulness of calling these “paradigm shifts” is debatable. While Miller’s finding Julie—and what the protomolecule was doing to her—was a significant discovery, Alex and Amos’s discovery of Holden’s relationship hardly seems comparable. Still, Miller’s finding Julie did bring with it problems (how can he prevent Eros from crashing into Earth?), solutions (he can try to get through to what remained of Julie’s consciousness), and values (doing so requires caring about open communication and even love). Holden’s relationship also brought with it problems (how can he and Naomi be together if they don’t completely trust one another?), solutions (they need to be prepared for rough waters), and values (doing so requires earning trust) too. We might even say that “Miller” before and after he finds Julie refers to different kinds of things—not just because he gets disassembled but also because his mission is complete. Certainly, “Holden” acts differently before and after he makes his personal life public, and life among the crew does change. We may want to say that in each case viewers are responding to a different (narrative, romantic, social—what have you) world. Maybe a kind of incommensurability gets a grip on these paradigm shifts too.

Regardless, one thing is clear. Kuhn’s idea of a paradigm shift was itself a paradigm shift. The idea was a significant discovery about how science and ultimately society works. It involved problems (what does “paradigm shift” mean and how can it be applied?), solutions (it has multiple overlapping meanings and applies really broadly), and values (doing so requires creativity and trying the idea out for size). The idea of a paradigm shift also caused a change in scientific and philosophic worldview, as scientists, philosophers, and now science-fiction novelists use it to understand the world. It even helps us understand the scientific and philosophic worldview of The Expanse.

Nathaniel Goldberg is professor of philosophy at Ceres Mining and Tech University, which stands on the grounds of a private university in Lexington, Virginia. Besides two academic books, he’s written Superhero Thought Experiments, which reads superhero comics as philosophy.

[1] In “Paradigm Shift,” Mao is trying to convince Mars that that the protomolecule is a technology that can create super soldiers. Also in the episode, Earth scientist Dr. Michael Iturbi explains that while U.N. Marine Corp Col. Janus thinks that Eros’s collision course for Earth is due to “a new Martian weapon, some staggering breakthrough on an incredible scale of a technology they’ve been pursuing utterly unsuccessfully for years,” he thinks that what’s behind Eros is “an entirely new order of technology, something from somewhere else, somewhere beyond the reach of our species.” Finally, in “Abaddon’s Gate,” season 3, episode 13, Earth, Mars, and the Belt realize that the protomolecule’s technological purpose was to create the interplanetary Ring Gate. I explain all this below.

[2] Thomas Kuhn, The Structure of Scientific Revolutions (Chicago: University of Chicago Press, 1st ed. 1962, 2d ed. with postscript 1970, 3d ed. with index 1996).

[3] Kuhn, Structure, 111.

[4] Ibid., 1.

[5] Ibid., 187.

[6] See especially ibid., 9–11. Margaret Masterman (“The Nature of a Paradigm,” in Criticism and the Growth of Knowledge, ed. Imre Lakatos and Alan Musgrave [New York: Cambridge University Press, 1970], 59–89) claimed that Kuhn used “paradigm” with 21 different meanings. In response to Masterman and others, in Structure’s 1970 postscript Kuhn distinguished what I identified above as the primary sense of “paradigm” (as “exemplar”) from other elements of a “disciplinary matrix,” including symbolic generalizations, metaphysical commitments, and values. In his final publications, anthologized in The Road Since Structure (Chicago: University of Chicago Press, 2000), Kuhn stopped talking about “paradigms” almost altogether, instead understanding its core concept in terms of the vocabularies—his “lexical taxonomies”—that scientists use. For more on Kuhn, including citations to other research, see my Kantian Conceptual Geography (New York: Oxford University Press, 2015), chap. 2, and my and Chris Gavaler’s Revising Fiction, Fact, and Faith (New York: Routledge, 2020), chap. 5.

[7] Protogen was a wholly owned subsidiary of Mao-Kwikowski Mercantile, which was wholly owned by Mao.

[8] Kuhn discusses Franklin at Structure,10, 13–15, 17–21, 40n5, 62, 106, 118, 122, 151n5.

[9] Ibid., 111.

[10] Ibid.

[11] Ibid., 110.

[12] Ibid., 98–103.

[13] Ibid., 10–11.

[14] See Goldberg and Gavaler, Revising Fiction, Fact, and Faith, 109–112.

[15] We can read Iturbi’s exchange with Avasarala as supporting this interpretation too. Eros moves in a way that practically defies the laws of physics but probably doesn’t do so in reality.

[16] We might also identify Miller’s coming to see himself over the course of season 1 as a washed-up cop, which made him to try so hard to find Julie, as a paradigm shift in which his—and ultimately Earth, Mars, and the Belt’s—world changed too. Likewise, in “Back to the Butcher,” season 1, episode 5, we learn that Johnson, then a U.N. marine colonel, was ordered to massacre Belter miners and families on Anderson Station, without being told that they had agreed to surrender. Earning the title “The Butcher of Anderson Station,” Johnson was so disgusted by his actions and the Earth government that ordered them, that he joined the O.P.A. His world changed from one in which Earth was justified in its actions to one in which the O.P.A. was, even when it resorted to what Earth and Mars considered terrorism.

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