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Summer screens are mostly showing franchise films, including "Indiana Jones," "Mission Impossible" and "Spiderman" sequels. "Barbie," based on the pre-release hype, hopes to be the next popcorn movie staple as Mattel bids to be the next Marvel.

But incongruously — incredibly, even — comes "Oppenheimer," a biopic (or horror film, given its focus on nuclear warfare) about J. Robert Oppenheimer, credited as the "father of the atomic bomb." An extraordinary, unflinching film that premiered on Friday, "Oppenheimer" seems more suited to winter, when more serious cinema is released before awards season, a circuit director Christopher Nolan and the "Oppenheimer" cast will surely travel.

One thing seems certain: "Oppenheimer" won't have a sequel.

At least at the Cineplex.

In the theater of the absurd of politics, however, sequels to the film's depiction of how official Washington persecuted the Manhattan Project's leader seem frequent. Lately, the targets have been epidemiologists and climatologists enduring political heat.

"I find the aftermath more interesting than the buildup to the Manhattan Project," said Michel Janssen, a University of Minnesota professor of physics and chemistry.

Referring to the Machiavellian machinations that stripped Oppenheimer of his security clearance because of associations with previous Communist Party members and sympathizers (including his wife, Kitty), Janssen added that when moviegoers depart "Oppenheimer" (likely silently, at first), "I hope they walk out of there pretty outraged at what the government did to one of its most important science advisers."

"This is taking place against a background of McCarthyism in a completely poisoned, toxic political environment," Janssen said about the Oppenheimer era. Switching to today, he added: "The parallel almost forces itself upon you, that again we're living in a highly toxic, heavily polarized environment in which politicians have to maneuver and have to factor in what the scientists are telling them." Or not factor it in, as was the case with "people like [Dr. Anthony] Fauci, and this strange lining up of whether or not you were in favor of vaccines depending very much on where you are on the political spectrum."

Others trying to protect the public seem in need of protection themselves, including meteorologist Chris Gloninger, who left KCCI in Des Moines last month because he developed post-traumatic stress disorder over the threats he received for on-air climate change coverage.

Yet more than ever, the world needs scientists and activists to explain the facts and advocate for action on existential threats like climate change and nuclear proliferation (and perhaps soon, uncontrolled artificial intelligence).

Organizations like ICAN, the International Campaign to Abolish Nuclear Weapons, which won the 2017 Nobel Peace Prize for "its work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its groundbreaking efforts to achieve a treaty-based prohibition of such weapons."

ICAN, sensing the intense interest in "Oppenheimer," released an open letter last week from a coalition of Hiroshima and Nagasaki atomic-bombing survivors that urged Nolan "to spark awareness and debate of the contemporary threat nuclear weapons pose, as well as the current global efforts to abolish them."

Those voices are profound and even more powerful than the Peace Memorial Park, accompanying museum, and iconic A-Bomb Dome, as I learned during a 2014 reporting trip to Hiroshima.

One of the three survivors I interviewed, Kenji Kitagawa, said that "World peace is kind of a dream far away. It might be difficult, but we have to do something, and the goal is the total ban of nuclear weapons. I feel what I am doing is so small, but one seed of grain will get the crop in the future."

That's the ethos of ICAN, whose can-do approach has already led 68 nations to ratify the U.N. Treaty on the Prohibition of Nuclear Weapons.

For many, ICAN's quixotic quest will seem naïve, even dangerous. But the organization isn't pressing for unilateral disarmament, but verifiable steps among nuclear nations — the same process that just this month finally rid the world of another scourge, chemical weapons, after the U.S. destroyed the last of its deadly arsenal.

A renewed focus on nuclear weapons can't come a moment too soon, according to the "Doomsday Clock," the metaphorical device set every year by the Bulletin of Atomic Scientists, an organization founded by Albert Einstein and University of Chicago scientists who worked on the Manhattan Project. This January, the clock was moved to 90 seconds to midnight — "the closest to global catastrophe it has ever been," the group said in a statement. Factors include "Russia's thinly veiled threats to use nuclear weapons" in Ukraine, which "remind the world that escalation of the conflict — by accident, intention or miscalculation — is a terrible risk."

Indeed, "nuclear-weapons risk are higher than they've been in my lifetime, and for many of your readers as well," said Susi Snyder, ICAN's program coordinator. Speaking from the Netherlands, Snyder said that "there's really two ways this story could end: It could end with nuclear war, and that takes away everything, or it can end with negotiated, verifiable disarmament."

Agreeing to the treaty is not easy, concedes Snyder. "It takes so much courage, and it takes patience, and it's hard work to negotiate. But it's the right way to go, and that's the choice we're faced with. And I really hope that people look at this film and get a chance to think about it, to digest it, and think, 'What is it that we want?'"

It's a question Oppenheimer and many Manhattan Project colleagues increasingly wrestled with, reflected in the film's depiction of a duality between the scientific thrill of accomplishment with the moral reckoning of the bomb's use and inevitable proliferation.

"On the one hand, his opposition and his qualms are balanced by a deference to politicians," Janssen said of Oppenheimer. "But on the other hand, his revulsion of these weapons is [balanced by] this fascination with the technicalities."

Amid an era when scientists are often hounded, not honored, for their work, the film's celebration of the "technicalities" and the scientists' intellectual integrity and outright joy is welcome. But so too is the film's focus on the forces unleashed.

"'Oppenheimer' tells the story of the beginning of nuclear weapons," said Snyder. "But the story of how nuclear weapons end hasn't been written yet. And we're writing it right now, and that's what I want people to take away — that this story isn't over, and we can choose the ending of nuclear weapons."

"It's going to be intense to see his movie," concluded Snyder. "But heavy doesn't mean hopeless."