I. Caesium Isotopes

Caesium-133 and caesium-137 (hereafter referred to by the mass number notation ¹³³Cs and ¹³⁷Cs) are isotopes of the chemical element caesium. Isotopes are variations of an atomic element that retain the same number of protons but have different neutron counts.¹¹ Caesium-137, also called radiocaesium, is a byproduct of thermal-neutron fission.¹² Of the many radionuclides and fallout products produced by fission reaction devices, ¹³⁷Cs is especially dangerous due to its high yield, relatively short half-life, high-energy decay pathway, and chemical reactivity.¹³ The yield of caesium-137 is as high as six percent of the total decay product produced by the fission of uranium-235, while the thirty year half-life (notated ¹³⁷Cs—T_(1/2) = 30.2 years) is long enough to remain in the environment over long periods of time. But it is also short enough to constitute a major radiological hazard, due to the 662 kilo-electron volts of ionizing radiation produced during its short decay pathway.¹⁴ Caesium owes its reactivity to its outermost electron, which accounts for its biokinetic behavior in human tissues as well as for the regular frequency of the spin transition of its outermost electron, essential to understanding the impact of fallout on human populations and the standardization mechanisms of atomic clocks, respectively.¹⁵ Caesium, like the rest of the alkali metals, has an atomic structure characterized by tightly-bound, paired groups of electrons in the lower energy state orbitals around the nucleus, but only one, unpaired electron in the orbital with the highest energy state. Despite those fifty-four other paired electrons, like hydrogen, only the nucleus and the outer, unpaired electron contribute to the magnetic state of the atom.¹⁶ In other words, the outer electron informs the essential behavior, and by extension the analogical cogency, of both caesium-137 and caesium-133, even though the former is a fissile product and the latter is radioactively stable.

Radiocaesium behaves much like another alkali element, potassium, when it is absorbed by the gastrointestinal tract:¹⁷ “cesium has been shown to compete with potassium for transport through potassium channels and can also substitute for potassium in activation of the sodium pump and subsequent transport into the cell.”¹⁸ As sodium ion pumps work by means of an electrochemical gradient, and the outermost electron in the caesium atom has an affinity for intracellular binding sites, the sodium pump may, in radioactive environments, exchange sodium ions for ions of caesium-137 within human bodies.¹⁹ Conversely, where ¹³³Cs is concerned, the outermost electron is essential in the engineering of atomic clocks and helps to provide the definition of the second according to the International System of Units. In hydrogen atoms “both the nucleus and the electron… behave like tiny bar magnets.”²⁰ When the orbital shell of the electron is aligned with the proton in the nucleus, the electron is repelled and pushed further from the nucleus, into a more excited energy state, and when the alignment is inverted, the electron is drawn closer to the nucleus, into a lower energy state, with the consequent energy jump having a corresponding oscillatory frequency.²¹ “Every caesium atom,” writes theoretical physicist Tony Jones, “will emit or absorb spin–flip photons at precisely the same frequency… Caesium atoms are like very precisely tuned radio receivers.”²²

In 1957, Louis Essen and John Parry of the National Physical Laboratory in the United Kingdom published their measurements of a quartz ring oscillating clock against the oscillatory frequency of ¹³³Cs. While the caesium beam oscillator itself did not function as a clock, but rather as a calibrator, in a paper which appeared in the Transactions of the Royal Society, Essen and Parry demonstrated a standard deviation in the quartz oscillator of 1 in 1010, indicating that the caesium isotope calibrator vibrated with a consistency that ushered in a “definitive standard of frequency and time.”²³ The International System of Units classified the caesium-133 atom as an “atomic parameter,” and as of 2019, the fundamental constant for the second has been expressed as the “unperturbed ground state hyperfine transition frequency of the caesium-133 atom,” or exactly “9,192,631,770 hertz.”²⁴ “Time no longer has a face or hands,” writes Karen Barad, “but it does have a rhythm, a pulse. The [caesium] atoms barely moving, habituated to temperatures near absolute zero, quantum leaps—dis/ continuities—define the continuous march of time.”²⁵

II. Atomic Clocks and the Time of Empire

I highlight these atomic characteristics to, in the case of ¹³⁷Cs, demonstrate how the isotope “remains dangerous for over three hundred years; easily transports through water, plants, and animals; and has shown up consistently in food produced in downwind zones decades later.”²⁶ In the case of ¹³³Cs, however, I place the chronometrical work of Essen and Parry into conversation with the consequences of the standardization of time on either side of the imperial encounter in order to understand how ¹³³Cs constitutes the “temporal armature of imperial spatialization.”²⁷ By comparing caesium-133 and caesium-137, my aim is not to scaffold a contrast between the readily perceptible physical harms of radiation and the long-term, diffuse harms consequent of the hierarchical power relations of chronopolitics, but rather draw attention to the ways in which the time standards determined by caesium isotopes precede and reinforce the militaristic systems responsible for the dispersal of fallout, including caesium-137.

Temporal homogenization and hierarchization as outcomes of chronometrology, or the measurement and standardization of time, precede Essen and Parry’s work with the caesium standard. Most notably, the 1884 International Prime Meridian Conference, which established Greenwich as the zero-degree meridian line and established the International Date Line at the 180-degree meridian, attempted to rectify the issue of “temporality as a zone of instability for the logic of global imperialism” by reconfiguring the development of time standards to resemble cartographic representations of spatial relations.²⁸ Put differently, the partitioning of time into standardized zones mirrors colonial border-making practices that prioritized imperial convenience over lived social and territorial realities. The International Date Line is located in the middle of the Pacific Ocean “because Great Britain was the leading maritime nation at the time, and most of the world could not have cared less where the date line was located, as long as it was far away, at the end of the world.”²⁹ Placing the International Date Line “at the end of the world” so that “every point on earth could be positioned in chronological sequence” is an example par excellence of the simultaneous representation of the many nations of the Pacific as tiny and peripheral, easily forgotten, and a consolidation of an enormous geographic region into a unified—and easily demarcated and consumable—whole.³⁰ The isolation and economic insignificance of the Pacific narrativized by colonial powers is consequent upon the standardization practices arising from the 1884 International Prime Meridian Conference and the establishment of the zero-meridian line. And today, the seconds that constitute the hourlong difference between each time zone—zones which fan out from the modern iteration of the International Date Line—are coordinated by the hyperfine frequency standard of caesium-133 atomic clocks.

Scholars across disciplines note that, before efforts aimed at global standardization gained significant traction, timekeeping was a localized practice specific to each culture’s needs and environment. In the Marshall Islands, timekeeping systems are closely aligned with seasonal cycles, lunar and celestial observations, and environmental patterns like tide tables and the strength of ocean current. Jack Tobin, an American anthropologist who documented Marshallese folktales, cites a ri-bwebwenato (storyteller) named Jelibōr Jam who recounts a chronometrological system intricately tied to weather and ocean conditions:

The sky was cut in half… And when the moon was there at one o’clock, going down to three o’clock, they named it Limeto… The reason they said, “Limeto” is because of big battles. (In the ancient language this is wind and rain.) And if the canoe is going to sail at this time, when it is Limeto, you load aboard. But if it is bad weather, you off-load (do not go). Because a lot of rain and wind come up suddenly. And they call it Limeto… However, when there is no rain and much wind, and the moon is in the west, well, perhaps these things (rain and wind) will come down at the time when the moon is in the east, in the middle. At this time, you will recognize that you will still not know when it will come down, rain or a big wind. But when the moon is in the Tutuinae, well, ignore anything and you should sail, for it is the right night to sail. It is ended. (They use this to this day)³¹

Comparing the ri-bwebwenato’s account of the subjective and emergent factors behind time and tide tables to a brochure about Kwajalein Atoll produced by the United States Army demonstrates the tension between place-based knowledge systems and the parameters of international time standards:

Kwajalein is west of the International Date Line, making it one day ahead of Hawaii and the continental United States. Officially, the time zone is MHT, or Marshall Islands Time, and is Coordinated Universal Time plus 12 hours. If it is 8 a.m. on Tuesday in Kwajalein, then it is 4 p.m. on Monday Eastern-Standard time in the US during Daylight Saving Time. The workweek on Kwajalein and Roi-Namur is Tuesday through Saturday, to correspond to the workweek in the United States³²

The two incompatible time systems in the Marshall Islands exemplify Mark Rifkin’s assertion that “Either they [Native peoples] are consigned to the past, or they are inserted into a present defined on non-native terms,” though the situation in the Marshall Islands demonstrates that the options mapped out by Rifkin may be commensurate rather than contrasting.³³ The imperial institutions behind the presence of a U.S. military installations at Kwajalein index knowledge systems like those practiced by the ri-bwebwenato as primitive or rudimentary due to their nonconformity to standardization, and thus their inability to be subsumed into global time frameworks. Simultaneously, the Marshallese people are bound to the seven-day workweek, a time system that is both ontologically disconnected from their worldview and epistemologically subordinated to coordinated temporal standardization and consequent homogenization—in the case of the Marshall Islands, of the archipelago by the continental colonial power. The homogenization, what Barbara Adam terms the “human machine-time of the West,” which is “used for colonizing purposes, defining in and out groups, distinguishing between the developed, developing and ‘non-developed’ world, designating some activities as productive while rendering others invisible.”³⁴ In other words, the International Date Line, Coordinated Universal Time, and “Time as the linear, predictable and disciplining coordination metrics of modern clocks and calendars” is both manifestation of and precondition to radioactive colonialism.³⁵ Atomic clocks, such as those regulated by the caesium-133 isotope, ensure the primacy of a homogenous temporal landscape over the heterogeneity of multiple temporal rhythms, to ends and by means that not only included “the violent oppression of indigenous and non-Western worldviews” but were conditional upon the same.³⁶ All this is to say that despite the staggered, non-simultaneous “events”³⁷ principally responsible for codifying and for rendering legible the aforesaid metrological projects with their end goal of, as Rifkin says, reifying “timescapes of expansion and dispossession,” the homogeneous representations of time, which are conditional upon a self-reinforcing synchronicity of atomic clocks, suggests that atomically-standardized time, rather than being a peripheral concern of colonial projects, is central to their formation and preservation.³⁸

III. Atomic Bombs and the Space of Radiation

The caesium standard makes legible a clock time that moves steadily in one direction, never backwards or laterally, can be owned and measured, and is extremely effective at reconciling imperial imaginaries of colonized communities and peoples as both peripheral non-players and readily possessed spoils. In effect, globally standardized time, derived from the frequency measurements of the caesium-133 isotope, and logistical infrastructures for military-imperial projects are self-reinforcing. Despite being subject to similar radiochemistries in the behavior of their outermost electron, caesium-133 does not experience the gamma decay that makes its cousin isotope, caesium-137, so dangerous. However, as a necessary ingredient of international atomic clock time, ¹³³Cs makes legible the importance of temporality, and by extension chronopolitics, in all facets of international political practice, including but not limited to the fostering of resource exploitation and the entrenchment of military influence in the Pacific. This military influence is, I argue, legible in the testing grounds and terminal beaches from which caesium-137 emerges as a principle radiological hazard.

At nine o’clock in the morning on July 1st, 1946, a B-29 plane dropped a plutonium implosion device 500 feet over Bikini Lagoon; it missed its target by half a mile.³⁹ The ignominious start of the test shot, codenamed Able, marked the commencement of Operation Crossroads, the first nuclear test series, the first deployment of atomic weaponry in a marine environment, and, at the time, the largest U.S. peacetime military operation ever conducted, involving tens of thousands of military personnel and hundreds of ships and aircraft.⁴⁰ Joint Task Force One, comprising Navy, Army, Air and Ground Forces as well as civilian scientists under the command of Vice Admiral W.H.P. Blandy, chose Bikini Atoll in the Marshall Islands as the staging ground for Operation Crossroads for three conditions. First, the depth of the lagoon offered a good anchorage for the “guinea pig fleet.”⁴¹ Further, the size, physical water conditions, and tropical marine climate were ideal for the charge weight and yield of the weapons being tested, ensuring the test results contingent on the first condition remained uncompromised by environmental variability. Finally, task force commanders ascertained that Bikini was close enough to U.S. military bases to stage bombing runs but not so close to major shipping lanes or, incidentally, the population of the continental United States, that testing under the first and second conditions would constitute a safety concern.⁴² Where test shot Able was dropped from a B-29, test shot Baker, the second of the two nuclear detonations comprising Operation Crossroads, was suspended in a waterproof case ninety feet below the hull of one of the target vessels anchored in Bikini Lagoon.⁴³

Able was beset by issues before, during, and after the detonation: wanting to muster more congressional observers in order to ease tensions with the Soviet Union, President Truman ordered Able delayed from 15 May 1946 until 1 July 1946, which “placed the dates for each test well within the period of unfavorable weather prevailing in the Marshalls during the summer months,” a significant concern as meteorological conditions play a major part in the dispersal patterns of radioactive fallout like caesium-137.⁴⁴ Moreover, the Able fission device detonated off target.⁴⁵ Wasserman and Solomon detail accounts of shipboard observers with their Geiger counter needles fixed at maximum, servicemen’s families whose children, following test Able, were born nonambulatory or with cerebral palsy, and civilian photographers who died of bone cancer in the two decades subsequent to filming the fireball over the lagoon.⁴⁶

Almost immediately following test Able’s detonation, and certainly in the aftermath of the subsequent Baker test shot, all three parameters by which Joint Task Force One originally adjudged Bikini’s suitability proved either misleading or outright erroneous. The depth of Bikini Lagoon, which factored into the anchorage of the test fleet, proved a significant radiological hazard after test Baker lofted “a one-mile-wide dome of water into the sky… like Niagara Falls in reverse.”⁴⁷ More, due to resistance caused by density, the column of the Baker subsurface detonation was significantly shorter (6,000 feet high) than the preceding Able test (36,089 feet high), whose own altitude “served to remove most of the radioactive fission products from the lower atmosphere.”⁴⁸ Consequently, when the millions of tons of highly irradiated water raised in the Baker column plunged back into the lagoon, the debris and spray contaminated everything in the immediate vicinity.

The delay in test Able rendered the meteorological appraisal of Bikini out of date and unreliable; Able pushed Baker back to later in the summer, when the climate of the Marshall Islands trends towards higher heat indexes, higher dew point averages, and higher levels of precipitation.⁴⁹ The moisture level was such that scientific instruments used by U.S. military personnel had to be continuously dehumidified, and test Able’s general safety measures, according to the Joint Task Force documents, did not include protective goggles.⁵⁰ The high humidity, coupled with the conditions of Baker’s subsurface burst, resulted in “nearly half the bomb’s fission products [falling] back into the lagoon’s water or onto the target ships.”⁵¹ A combination of the displaced mass of the lagoon, debris from the bomb casings and pulverized islets, and extremely radioactive water droplets condensed from the humid air created a base surge that washed over the test fleet and rendered most of the target vessels unsalvageable, “shellacked with unexpectedly tenacious, and long-lived, radioactivity.”⁵²

In deconstructing the final criterion used in Joint Task Force One’s decision, that of Bikini’s remoteness, I return to Cornum: “The irradiated international prompt consciousness to understand the scales of the planetary.”⁵³ Radiation is both spatially and temporally unbound in Earth systems. According to a 2018 report, “Caesium-137 (¹³⁷Cs) is one of the most abundant anthropogenic radionuclides in the marine environment.”⁵⁴ More, the proximity of the Marshall Islands to the Kuroshio Current and Kuroshio extensions as well as the North Equatorial Current (NEC), part of the subtropical gyre in the North Pacific Ocean, means that ocean currents would efficiently recirculate much of the radioactive fallout deposited by the bombs detonated in Bikini. The Pacific North Equatorial Current’s seasonal trade winds dominate the climate of islands and archipelagoes situated along the North Pacific subtropical gyre; the stratosphere–troposphere exchanges of the trade winds continue to deposit radioactive fallout on the Earth’s surface long after any initial nuclear detonation.⁵⁵

For fallout products like radiocaesium, which have half-lives decades long, the isotopes circulate and spread over years and cover spatial distances measured in thousands of miles. For example, Guam, situated a little over 1,000 miles west of the Marshall Islands, “is located directly downstream from the largest source of bomb-produced radioactivity in the Pacific Ocean,” which, along with falling directly in the North Equatorial Current at 13 degrees latitude, renders it especially susceptible to radioactive debris from fallout.⁵⁶ After the detonation of Ivy Mike, the first test series of a thermonuclear device, Charles Bert Schreiber, a lieutenant in the U.S. Navy and the Radiological Safety Officer stationed on Guam, testified that the dial needle on his calibration dosemeter “went off the scale (as far as it could swing right). I knew it was not the counter, but that there was some radioactivity outside.”⁵⁷ In a 2016 study headed by the University of Arizona’s Department of Geosciences, coral cores collected from Agat, Guam recorded a spike in radioactive iodine-129 more than “100 times pre-nuclear values… due,” the report speculated, “to above-ground nuclear weapons testing carried out in the 1950s in the Pacific Ocean.”⁵⁸

Of the many radiological surveys conducted across Pacific Oceania, I have elected to cite the study carried out by the University of Arizona for two reasons: one, because of Arizona’s own troubled history with nuclear imperialism, exemplified by the radioactivity in the Puerco and Little Colorado River basins owing to more than two decades of uranium mining (some of which ended up in the bombs dropped in the Pacific) and the 1979 failure of an earthen dam containing mine tailings, an example in microcosm of the generational harm done to Native American lands and communities happening alongside, and indeed ineluctably entangled with, the destruction in the Pacific.⁵⁹ Two, because in extending my analysis beyond the Marshall Islands and placing Guam at a critical juncture in the conversation, I hope to emphasize that the dispersal of radioisotopes subsequent to the detonations themselves situates nuclear weapons on the spacetime scales of a truly global nuclear empire. Able and Baker are flashpoints but, according to Cornum, “the violence of the bombs itself is not contained to the flash of a single event.”⁶⁰ Like caesium-137, the fallout persists, and like caesium-133, Able and Baker force an attentive eye on the underlying infrastructures of radioactive colonialism that are insidious, well-entrenched, and tremendously difficult to disentangle.

IV. Retrospective Research

As evidenced by the important scholarship cited throughout this article, interrogations into the ways in which standardized timekeeping facilitates the coordination of radioactive colonialism and examinations of the horrific aftermaths of nuclear weapons testing are, while critical to postcolonial scholarship, not wholly new avenues of investigation. The principal objective of this essay, therefore, has been to place these two strains of criticism into conversation with each other, and to do so with recourse to the element caesium. Caesium is a pacemaker and a waste-product, a time standard and a source of radiation sickness, with isotopes that constitute both a fortification of and fallout product from the military-imperial projects of radioactive colonialism. Rather than taking the precise and invariant standards made possible by atomic clocks as a priori—these “economic time values, associated with the trade in time and inescapably tied to the creation of clock-time… imposed as globally standardized norm”⁶¹—my hope is that the figuration of caesium-133 will compel scholars to scrutinize the homogenizing power of Coordinated Universal Time and its calibrating armada of atomic clocks, as well as their function as a regulatory ideal that serves to stabilize and coordinate projects of radioactive colonialism. In the case of caesium-137, my hope is for this scrutiny to function proactively, informing regulatory measures aimed at forestalling the future manufacture, stockpiling, and proliferation of nuclear weapons, as well as retroactively in assessing the true scope and scale of the traumas caused by living downwind of nuclear test sites.

The relationship between caesium, fallout, and diseases associated with ionizing radiation exposure is well-established, but the relationship requires renewed scrutiny in the context of the test series carried out immediately after World War II. As evidenced by the relative absence of safety details in the operational reports and documentation compiled by the Atomic Energy Commission and Joint Task Force One, compared to current data, not as much was known about the toxicology of caesium-137 at the time of Operation Crossroads and subsequent test series. A January 1956 meeting of the Advisory Committee on Biology and Medicine convened by the AEC yielded the following: “We don’t know enough about the induced activities… to be able to come up with a good material balance,” says Merril Eisenbud, the health and safety chief. “Or, putting it in another way, to come up with a good estimate of what the radiological picture would be if, instead of being a clean weapon, it was a dirty weapon of bravo [thermonuclear] type… there has been a great deal of emphasis placed on the need for better fallout information.”⁶²

Eisenbud later noted to Congressman Lane Evans, during a 1994 Oversight Hearing on Radiation Exposure from Nuclear Test Sites in the Pacific convened by the House of Representatives Natural Resources Committee, that while the “data [impact on human beings] from the Japanese experience [Hiroshima and Nagasaki] was… meaningful because the numbers of people were very much larger,” there was a notable lack of data regarding fallout deposition because the “bombs were exploded high in the air” and thus produced relatively little fallout.⁶³ Conversely, Eisenbud states that “At BRAVO [thermonuclear test Castle Bravo], we had the combination of about 175 rem [a measurement of the dose of damage to a human from radiation] of external exposure plus the concomitant exposure from internal emitters. These are the radioiodine and the cesium that gets inside the body and irradiates the body from the inside.”⁶⁴ Or, in the words of Barton C. Hacker, the historian to the Department of Energy’s Dosimetry Research Project, “This was less a failure of data than of perception.”⁶⁵ It is vitally important to revisit the data from military operations like Crossroads armed with more current and comprehensive toxicological profiles of radioisotopes like ¹³⁷Cs. In a statement before the House of Representatives Natural Resources Committee, Jonathan Weisgall, who served as legal counsel for the Marshallese displaced from Bikini, emphasized that the tolerance standards have changed dramatically over the last half century. Doses “deemed appropriate in 1946” were lowered “by a factor of 365” by 1994, “so that today the current recommended maximum dose for one year is approximately the same dose that was recommended as the maximum exposure for one day at Operation Crossroad.”⁶⁶

While the bulk of this analysis has concerned the sixty-seven nuclear tests carried out in and around Marshall Islands by the U.S. between 1946 to 1962, this article might also have readily included other nuclear tests in line with Cornum’s formulation, a truly international mapping. The United Kingdom conducted weapons tests on Malden and Kiritimati Islands in Kiribati, the Montebello Islands off the coast of West Australia, and Emu Field and Maralinga in South Australia; France tested weapons on Moruroa and Fangataufa in the Tuamotu Archipelago up until 1996.⁶⁷ In order to effectively address the inquiries of this special issue, I have chosen to focus on the series of nuclear tests conducted by the United States in the Marshall Islands: while this deliberate limitation allows for a more in-depth and contextually relevant exploration of the spatial and temporal mappings made possible by caesium isotopes and their biological and ecological metabolisms, this article is only a narrow inroad.

My hope is that the frameworks of spatial irradiation and temporal standardization sketched out by caesium and its isotopes may offer new avenues into researching the irradiated international, not only in the interest of reassessing the environmental health impact, but in informing comprehensive, long-term solutions to securing reparations for affected communities. In 2009, for example, Delegate Madeleine Z. Bordallo of Guam co-sponsored House Bill 1630, which was intended to amend the Radiation Exposure Compensation Act (RECA) to make residents of Guam eligible for the same compensation benefits as those of the Marshall Islands and other downwind nations; in 2005, an assessment carried out by the National Academies of Sciences, Engineering, and Medicine found that Guam “did receive measurable fallout from atmospheric testing of nuclear weapons in the Pacific.”⁶⁸ However, while House Bill 1630 was later referred to the Subcommittee on Immigration, Citizenship, Refugees, Border Security, and International Law, as of this writing, the Bill is dead in committee.⁶⁹ Although Congress did pass a major expansion and reauthorization of RECA in July 2025 (part of the 2025 Budget Reconciliation Act, or the so-called “Big Beautiful Bill”), Guam was excluded from the final legislation.⁷⁰ Armed with current data, retrospective evaluations of fallout deposition, metabolic uptake, and biologic injury—not only of radiocaesium, but other radioisotopes, and not only in the context of the Pacific, but across all test sites—can be vital to establishing legal frameworks to guide reparations for victims and downwinders of nuclear tests. Even more than a half century after the atomic tests carried out by the United States—and, incidentally, far less time in the case of nuclear states like France—it is vitally important to continue to devote time and research to these data to contextualize the enormity of the environmental and humanitarian devastation.

V. In conclusion

Reckoning with the symmetry between past and future trauma instantiated by the nuclear test series carried out across the Pacific involves accounting not only for the more obvious dangers posed by fallout and radiation but for the complicity of supposed apolitical actors like caesium clocks. Caesium is a lens that refocuses ongoing conversations about the biological, ecological, and cultural consequences of nuclear weapons tests to create a dialogue between the deposition of fallout materials and the entanglements between time, standardization, and imperial reach, particularly in terms of the cascading, self-reinforcing amplification extant between the two. As historian Gabrielle Hecht notes: “Once the weapons were built, the imperial cycle began anew, with atomic bombing—more palatably referred to as “nuclear testing”—of the Marshall Islands, the Sahara, the Navajo Nation, Maralinga, Moruroa, and other colonized spaces.⁷¹

The caesium model functions as an analytical hybrid of clock and atlas, sketching a spacetime atomically-standardized and atomically-irradiated. But I want to suggest, perhaps, that the spatiotemporal frameworks dispersed by fallout and tangled in nets of latitude and longitude can, in fact, be undone by their own quantum-mechanical scaffolding. Caesium-137 is one of the more ubiquitous radioactive fission products; it is also an isotope, like all isotopes, wherein one cannot know both the position and momentum of its constituent electrons with absolute precision. Caesium-133 provides the numerical value of a base time unit, a formative foundation of a complete and consistent system of temporal standardization. But as Scott Alan Johnston notes, “atomic clocks are subject to the whims of political agreements about, for example, the length of a second or the arbitrary width of a time zone… it is not physics that determines time, but politics.”⁷²

Beyond the frame of frequency transitions and gamma-ray emissions, beyond manifestations of chronological formalizations and fallout dispersal, the “nuclear”—from the Latin word meaning kernel or seed—invites considerations of the metaphysical potentialities promised by the mechanics and mathematics of quantum-level processes. As has been done by Mark Rifkin, who in his Beyond Settler Time puts the relativistic temporal mechanics of Einstein into conversation with Indigenous constructions of time, and Elizabeth LaPensée, an Anishinaabe and Métis scholar and video game creator whose work Along the River of Spacetime activates Anishinaabe star knowledge using the quark experiments carried out by the Large Hadron Collider,⁷³ I propose that the cosmologies disclosed by the field theories of disciplines like quantum mechanics offer indeterministic in-roads in which any adequate ontological formulation requires employing conceptual tools that veer into modes of world-making far more radical and speculative than the standardization of spacetimes by colonial and military powers. By virtue of their quantum mechanical characteristics, the material of atomic fallout, and of atomic timekeeping, is paradoxical for its capacity to both wound and, perhaps, mend. Like the measurement of a particle’s position, like the crest of a wave on the cusp of collapse, what emerges from the probability densities and strange quantum possibility spaces are a multiverse of alternative spacetime formulations. For those trained in quantum physics like Karen Barad, “Each bit of matter, each moment of spacetimemattering, is shot through with an infinite set of im/possibilities for materially reconfiguring worlds and pastfuturespresents”⁷⁴ For postcolonial scholar Vilashini Cooppan, perhaps the caesium model might, like a tide in retreat, give away to “soft time… striated by lateral connections, by roiling waves of forward and backward movement, time marked by the lapping of ocean on sand, water on stone, and the ongoing making of new creolized identities”⁷⁵ For Kathy Jetn̄il-Kijiner, whose home was ground zero for those sixty seven flashpoints of radioactive colonialism, moving beyond standardized time and irradiated space involves invoking a cosmology of baskets and birth mothers, oceans mapped beneath “the hollow hulls / of canoes as fast as the wind / slicing through the pacific sea” and moments metered by the “sweet harmonies / of grandmothers mothers aunties sisters— / songs late into the night.”⁷⁶

Surveying radioactive empires through the lens of caesium offers a mode of analysis that entangles the dispersion of radioactive material with the colonial systems that both enable said dispersal and are, in turn, enabled by it, a framework capable of illuminating the networks of relationality necessary to conceive of actionable strategies of redress and reparation. A first step, perhaps, in foregrounding cosmologies and spacetimes attentive to dynamic material configurations, processes of change and emergence, and diverse communal entanglements, a reclamation of that which atomic clocks and atomic fallout have sought to drown out under the sounds of second hands and Geiger counters.

Competing Interests

The author has no competing interests to declare.