
Cai Guo-Qiang, “Color Mushroom Cloud” (2017), realized above the former CP-1 site, University of Chicago, on December 2 (photo by Zoheyr Doctor and Reed Essick, courtesy Cai Studio)
CHICAGO — On Saturday, December 2, a multicolor mushroom cloud shot into the sky over the former site of Chicago Pile-1 (CP-1), the world’s first artificial nuclear reactor, at the University of Chicago. The harmless explosion, witnessed by thousands, was the most recent pyrotechnic artwork by Cai Guo-Qiang, who has for decades worked with gunpowder, which he used to create large drawings before venturing into designing epic firework displays. Although shorter than previous blasts, this one, launched from the roof of a university library, was no less awesome: it sent streams of color whizzing upwards before erupting into bright puffs, like daubs on a painter’s palette, which left in their wake a dark, billowing mass of smoke.

Cai Guo-Qiang’s rainbow mushroom cloud dissipating (photo by the author for Hyperallergic)
“Color Mushroom Cloud” was commissioned by UChicago Arts and the Smart Museum of Art to commemorate the 75th anniversary of the first controlled, self-sustaining nuclear chain reaction. On December 2, 1942, physicist Enrico Fermi led the successful experiment on a subterranean squash court, where he and his team had built CP-1 and secretly conducted tests as part of the Manhattan Project. They ushered in the atomic age at 3:25 pm, which is the exact time Cai’s own cloud burst. It rose 75 meters, or 246 feet, above the roof of Regenstein Library — a festive eddy of colors floating above an ominous haze — before the wind swept the strange brew away.
The explosion was part of a series of public events the University organized over the weekend — from performances to panel discussions — that considered the past and future implications of nuclear energy, both positive and negative. As the threat of nuclear war intensifies with escalating tensions between the United States and North Korea, “Reactions: New Perspectives on Our Nuclear Legacy,” was particularly timely.
Unlike the daily news, however, “Color Mushroom Cloud” inspires awe much more than it summons fear, even though its physical form recalls a nuclear bomb in both its shape and resultant smoke. Despite this reference to war and death, I couldn’t help but gasp in wonder, and then applaud along with the rest of the crowd, at the marvel we had just witnessed. Like Henry Moore’s bronze statue of a mushroom cloud, erected 50 years ago on the former CP-1 site, Cai’s blast conveyed heaviness, but even more so, hope for the future in its literal transformation of explosives into ephemeral beauty. (Also, it was simply spectacular as a technical feat: Cai works with Fireworks By Grucci, which manufactures color aerial shells that are each embedded with a microchip, allowing you to program the exact moment of detonation.)

Cai Guo-Qiang, “Color Mushroom Cloud” (2017), realized above the former CP-1 site, University of Chicago, on December 2 (photo by John Zich, courtesy Cai Studio)
“Cai’s work, like fission itself, has the inherent dialectic of creation and destruction,” Laura Steward, The Smart Museum’s Curator of Public Art, told Hyperallergic. “The University feels like it has a solemn responsibility to investigate nuclear fission and think about our role here. So to keep its dialectic intact, I think, is super important.”
And yet, what are the implications of altering a visual as traumatic as the mushroom cloud, of transforming it into a festive display that risks bordering on spectacle? Cai has long examined the image of the atomic bomb, namely through his 1996 series, The Century with Mushroom Clouds: Project for the 20th Century, for which he detonated small mushroom clouds above his hand, often with no one else present.

Cai Guo-Qiang, sketch for “Color Mushroom Cloud” (image courtesy Cai Studio)
“Color Mushroom Cloud” takes on a completely different tone with its rainbow pigments and careful staging for a massive audience. One detail that helped frame it as a solemn event rather than an extravaganza was Cai’s decision to count down to the explosion with 75 tolls of the largest carillon bell at the University’s Rockefeller Chapel, which served as an opportunity for those present to reflect on the value of nuclear energy (although a glitch in the speaker system, around the halfway mark, that received and amplified the distant ringing broke any moment of contemplation).
Notably, when the 75th bell rang at 3:25 pm, another performance took place as all eyes (and cameras) moved to the sky. A dozen or so students lay on the ground, many in front of the audience, in a protest intended to critique the University’s framing of its series, which the group found generally too celebratory of nuclear energy. For about 20 minutes, they lay quiet and motionless as Cai’s cloud quickly dissipated, in order to underscore the human cost of nuclear war, as India Weston, who organized the action, told Hyperallergic.
“A lot of the events have been contradictory to one another and primarily frame things in more of a positive light than not,” Weston, a transmedia performance artist, said. “And yet, there’s no sort of threshold of acceptable nuclear energy exposure.”
“The University website claims that the cloud would dissipate harmlessly after about a minute, but that’s just not how radiation works,” they added. “It’s a geo-trauma that affects us all and will for generations and generations. So I was hoping to make more visible the all-too-invisible effects of radiation on the human body.”

Performance protest by University of Chicago students (photo by the author for Hyperallergic)

On the former CP-1 site at the University of Chicago (photo by the author for Hyperallergic)
Of course, if the University is bent on creating an explosion (and an expensive one, at that) it has to be a harmless one. To realize “Color Mushroom Cloud,” officials went to great lengths to ensure safety, both for viewers and for the environment. Researchers even conducted experiments with songbirds in one building, Steward said, to make sure the cloud’s powder would not be toxic if inhaled by area avians. It’s no easy feat to place explosives on the roof of a library in the middle of a college campus, and the organizing committee had to contact the alderman’s office as well as the police and fire departments before proceeding.
This complicated and lengthy process adds another interesting layer to Cai’s piece that further ties it to the history of CP-1. Those involved were preparing for a momentous moment that had volatile results, in a sense echoing the questionable nature of the work Fermi and his team undertook — both technically and ethically.
“The work has forced the whole University to think long and hard about its responsibility to this experiment, what kind of point of view it wants to put forward, and how to mark this commemoration,” Steward told Hyperallergic. “Working through this piece has caused some soul-searching throughout the University that’s been really fascinating. In making this mushroom cloud, we’ve gone through a small version of what the people around Fermi must have gone through.”
“Color Mushroom Cloud” could have failed for many reasons, but those in charge managed to control it, down to the desired minute of detonation — just as Fermi and his team created the necessary conditions to engineer a controlled nuclear chain reaction. Perhaps, more than anything, Cai’s artwork emphasizes humanity’s firm grasp of complex science and technologies. Let’s use that power with care.

Cai Guo-Qiang, “Color Mushroom Cloud” (2017), realized above the former CP-1 site, University of Chicago, on December 2 (photo by Wen-You Cai, courtesy Cai Studio)

Cai Guo-Qiang, “Color Mushroom Cloud” (2017), realized above the former CP-1 site, University of Chicago, on December 2 (photo by Zoheyr Doctor and Reed Essick, courtesy Cai Studio)

Henry Moore’s sculpture, “Nuclear Energy” (1967) with OPA’s temporary installation, “Nuclear Thresholds” (2017) (photo by the author for Hyperallergic)

Cai Guo-Qiang speaking on the former CP-1 site at the University of Chicago (photo by the author for Hyperallergic)