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Survivors Of The Trinity Nuclear Test Weren't Warned — Then Were Lied To After

Leila Fadel

Justine Kenin

Gabe O'Connor

NPR's Leila Fadel talks with Lesley Blume about the struggle of the survivors of the Trinity nuclear test in 1945 — one locals didn't know was coming and caused serious health issues.

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The Chilling Story of The 'Demon Core' And The Scientists Who Became Its Victims

It was August 13, 1945, and the 'demon core' was poised, waiting to be unleashed onto a stunned Japan still reeling in fresh chaos from the deadliest attacks anyone had ever seen.

A week earlier, 'Little Boy' had detonated over Hiroshima, followed swiftly by 'Fat Man' in Nagasaki.

These were the first and only nuclear bombs ever used in warfare, claiming as many as 200,000 lives  – and if things had turned out a little differently, a third deadly strike would have followed in their hellish wake.

But history had other plans.

After Nagasaki proved Hiroshima was no fluke, Japan promptly surrendered on August 15, with Japanese radio broadcasting a recorded speech of Emperor Hirohito conceding to the Allies' demands.

As it turns out, this was the first time the Japanese public at large had ever heard one of their emperors' voices, but for scientists at the Los Alamos Laboratory in New Mexico – aka Project Y – the event had a more pressing significance.

It meant the functional heart of the third atom bomb they'd been working on – a 6.2-kilogram (13.7 lb) sphere of refined plutonium and gallium – wouldn't be needed for the war effort after all.

If the conflict had still been raging, as it had for almost five straight years, this plutonium core would have been fitted into a second Fat Man assembly and detonated above another unsuspecting Japanese city just four days later.

As it was, fate issued those souls a reprieve, and the Los Alamos device – code-named 'Rufus' at this point – would be retained at the facility for further testing.

It was during these tests that the leftover nuke, which ultimately became known as the demon core , earned that name.

The first accident happened less than a week after Japan's surrender, and only two days after the date of the demon core's cancelled bombing run.

That mission may have never launched, but the demon core, stranded at Los Alamos, still found an opportunity to kill.

The Los Alamos scientists knew well the risks of what they were doing when they conducted criticality experiments with it – a means of measuring the threshold at which the plutonium would become supercritical, the point where a nuclear chain reaction would unleash a blast of deadly radiation.

The trick performed by scientists in the Manhattan Project – of which the Los Alamos Lab was a part – was finding how just how far you could go before that dangerous reaction was triggered.

They even had an informal nickname for the high-risk experiments, one which hinted at the perils of what they did. They called it "tickling the dragon's tail" , knowing that if they had the misfortune to rouse the angry beast, they would be burned.

And that's exactly what happened to Los Alamos physicist Harry Daghlian .

On the night of August 21, 1945, Daghlian returned to the lab after dinner, to tickle the dragon's tail alone – with no other scientists (just a security guard) around, which was a breach of safety protocols.

As Daghlian worked, he surrounded the plutonium sphere with bricks made of tungsten carbide, which reflected neutrons shed by the core back at it, edging it closer to criticality.

Brick by brick, Daghlian built up these reflective walls around the core, until his neutron-monitoring equipment indicated the plutonium was about to go supercritical if he placed any more.

He moved to pull one of the bricks away, but in doing so accidentally dropped it directly onto the top of the sphere, inducing supercriticality and generating a glow of blue light and a wave of heat .

Daghlian reached out immediately and removed the brick, noticing a tingling sensation in his hand as he did so.

Unfortunately, it was already too late.

In that brief instant, he had received a lethal dose of radiation. His burnt, irradiated hand blistered over, and he eventually fell into a coma after weeks of nausea and pain.

He was dead just 25 days after the accident. The security guard on duty also received a non-lethal dose of radiation.

But the demon core was not yet finished.

Despite a review of safety procedures after Daghlian's death, any changes made weren't enough to prevent a similar accident occurring the following year.

On May 21, 1946, one of Daghlian's colleagues, physicist Louis Slotin , was demonstrating a similar criticality experiment, lowering a beryllium dome over the core.

Like the tungsten carbide bricks before it, the beryllium dome reflected neutrons back at the core, pushing it toward criticality. Slotin was careful to ensure the dome – called a tamper – never completely covered the core, using a screwdriver to maintain a small gap, acting as a crucial valve to enable enough of the neutrons to escape.

The method worked, until it didn't.

The screwdriver slipped and the dome dropped, for an instant fully covering the demon core in a beryllium bubble bouncing too many neutrons back at it.

Another scientist in the room, Raemer Schreiber , turned around at the sound of the dome dropping, feeling heat and seeing a blue flash as the demon core went supercritical for the second time in the space of a year.

"The blue flash was clearly visible in the room although it (the room) was well illuminated from the windows and possibly the overhead lights," Schreiber later wrote in a report .

"The total duration of the flash could not have been more than a few tenths of a second. Slotin reacted very quickly in flipping the tamper piece off."

Slotin may have been quick in rectifying his deadly mistake, but again, the damage was already done.

He, and seven others in the room – including a photographer and a security guard – were all exposed to a burst of radiation, although Slotin was the only one to receive a lethal dose, and a greater one than that inflicted on Daghlian.

After an initial bout of nausea and vomiting, he at first seemed to recover in hospital, but within days was losing weight, experiencing abdominal pain, and began showing signs of mental confusion.

A press release issued by Los Alamos at the time described his condition as "three-dimensional sunburn".

Nine days after the screwdriver slipped, he was gone.

The two deadly accidents, only months apart, finally saw real changes take place at Los Alamos.

New protocols meant an end to 'hands on' criticality experiments, with scientists forced to use remote control machinery to manipulate radioactive cores at a distance of hundreds of metres.

They also stopped calling the plutonium core 'Rufus'. From then on, it was known only as the 'demon core'.

But after everything that had happened, the leftover nuke's time was up too.

Following the Slotin accident – and the core's resultant increase in radiation levels – plans to use it in Operation Crossroads , the first post-war nuclear explosion demonstrations to commence at the Bikini Atoll a month later, were shelved.

Instead, the plutonium was melted down and reintegrated into the US nuclear stockpile, to be recast into other cores as necessary. For the second and last time, the demon core was denied its detonation.

While the deaths of two scientists can't be compared to the untold horrors if the demon core had been used in a third nuclear attack against Japan, it's also easy to understand why the scientists gave it the superstitious name they did.

Then there are the weird details that fill in the backdrop of the story.

Like how Daghlian and Slotin weren't just killed by similar accidents involving the same plutonium core: both incidents took place on Tuesdays , on the 21st day of the month, and the men even passed away in the same hospital room.

Of course, those are just coincidences. The demon core wasn't actually demonic. If there's an evil presence here, it's not the core, but the fact that humans rushed to make these terrible weapons in the first place.

And the real horror – besides the horrible effects of radiation poisoning – is how spectacularly mid–20th century scientists failed to protect themselves from the extreme dangers they were toying with, despite fully knowing the grave risks in their midst.

According to Schreiber , Slotin's first words immediately after the screwdriver incident were simple, and already resigned.

He had comforted his dying friend Daghlian in hospital, and he knew what came next.

"Well," he said, "that does it."

The Crazy Story of the 1946 Bikini Atoll Nuclear Tests

They were the first time that a nuclear weapon had been deployed since the 1945 attacks on Japan

Kat Eschner

Operation Crossroads, which had its first big event–the dropping of a nuclear bomb–on July 1, 1946, was just the beginning of the nuclear testing that Bikini Atoll would be subjected to. When the first bomb of the tests dropped, it was the first time since the 1945 attacks on Japan that a nuclear weapon had been deployed. Here are three things you might not know about the infamous tests:

The test subjects were ghost ships full of animals

The goal of the tests was to see what happened to naval warships when a nuclear weapon went off, writes the Atomic Heritage Foundation. More than 42,000 people–including a crew of Smithsonian Institution scientists, as well as reporters and United Nations representatives,  according to Alex Wellerstein for The New Yorker –were involved in observing the nuclear tests, but the humans were, of course, not the test subjects.

Instead, “some of the ships were loaded with live animals, such as pigs and rats, to study the effects of the nuclear blast and radioactive fallout on animals,” writes the foundation. In total, more than 90 vessels, not all carrying live cargo, were placed in the target area of the bomb, which was named Gilda–after Rita Hayworth’s character in the eponymous film .

The gathered scientists included fish scientist Leonard P. Schultz, who was then the curator of ichthyology for the National Museum of Natural History.  Although he was given safety goggles,  writes  the museum, “he was doubtful whether the goggles would protect him.” So, in true scientific fashion, “he covered one eye and observed the explosion with the other.” His eyes were fine, and the effects that he felt included “a slight warmth” on his face and hearing a boom about two minutes after the flash.

Schultz and his colleagues were there to collect species and document the Atoll before and after the tests. They collected numerous specimens including sea and land creatures, writes the museum, which remain in the museum’s collections today. “The Smithsonian’s collections document the extent to which the diversity of marine life was affected by the atomic blasts,” writes the museum, “providing researchers who continue to ­study the health of the ecosystem with a means to compare species extant today with those collected before the tests.”

The first bomb missed its target

That reduced the damage done to the ghost ships. “The weapon exploded almost directly above the Navy’s data-gathering equipment, sinking one of its instrument ships, and a signal that was meant to trigger dozens of cameras was sent ten seconds too late,” Wellerstein writes.

It started a tradition of nuclear testing in this vulnerable place

“The nuclear arms race between the US and Soviet Union displaced 167 Marshallese as refugees in their own country,” writes Sarah Emerson for Motherboard . After the first 1946 tests, the U.S. government continued to use the area around Bikini Atoll and the Marshall Islands for nuclear testing, writes Erin Blakemore for Smithsonian.com, conducting 67 nuclear tests in total. 23 of those tests were conducted at Bikini Atoll specifically, including one 1954 test of the largest nuclear device the U.S. ever exploded.

The Marshallese displaced by the testing have not been able to go back to their poisoned homes. Today, it’s hard to know when the Atoll will ever be safe to return to, writes Blakemore, although the Marshall Islands overall are becoming less radioactive.

And it all started in 1946.

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Kat Eschner | | READ MORE

Kat Eschner is a freelance science and culture journalist based in Toronto.

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Nuclear Tests Have Changed, but They Never Really Stopped

Just before sunrise on July 16, 1945—75 years ago today—a patch of New Mexican desert was incinerated during the first trial of the most destructive weapon ever created. The plutonium bomb used for the Trinity test left a 5-foot crater in the ground and turned the surrounding desert floor into a radioactive green glass. The blast bathed the peaks of the nearby Oscura Mountains in a blinding white light, and dozens of scientific observers watching from 20 miles away reported feeling an immense heat wash over them. As the light from the explosion faded, one of the architects of the bomb, Kenneth Bainbridge, gave a pithy appraisal of the event to J. Robert Oppenheimer, the project’s lead scientist: “Now we are all sons of bitches.”

And he was right. Less than a month later, the United States dropped the same type of bomb on Nagasaki, Japan, just three days after detonating a smaller nuclear warhead over Hiroshima. It effectively ended World War II, but it came at the price of well over 100,000 civilian lives and the enduring suffering of those who survived .

The bombing of Nagasaki was the second and final time a country has deployed a nuclear weapon in combat. But it wasn’t the last nuclear explosion. Despite a lifetime of activism by Bainbridge and many of his colleagues, nuclear tests didn’t end with the war. By the time the US signed the United Nations Comprehensive Nuclear Test Ban Treaty in 1996 and agreed to stop blowing up nukes, American physicists and engineers had conducted more than 1,000 tests. They blew up nuclear weapons in the ocean. They blew them up on land. They blew them up in space. They dropped them from planes. They launched them on rockets. They buried them underground. A small army of US weapons scientists blew up a nuclear weapon every chance they got, and at the height of the nation’s testing program they were averaging one detonation per week.

The test-ban treaty was meant to end all that. Atmospheric nuclear tests have been internationally banned since the early 1960s due to health concerns about radioactive fallout and other hazards. These weren’t baseless fears. In the 1950s, US physicists drastically miscalculated the explosive yield of a thermonuclear bomb during a test in the Pacific Ocean, and the ashy radioactive fallout was detected as far away as India. Exposure to the fallout caused radiation sickness in the inhabitants of the islands around the test site, and a group of Japanese fishers suffered severe radiation burns when the fallout landed on their boat. Miscalculations of this sort were distressingly common at the time. Only a few years later, a bomber accidentally dropped a nuclear weapon on Kirtland Air Force Base on the outskirts of Albuquerque, New Mexico. (Fortunately, no one had yet loaded into the bomb the plutonium pits needed to kick off a nuclear chain reaction.)

The US signed the Partial Nuclear Test Ban Treaty—a bilateral agreement with the Soviet Union to cease above ground tests—in 1963. But nuclear testing only accelerated when it was pushed underground. The US nuclear arsenal peaked in 1967 with 31,255 warheads, and it detonated as many nukes in the 7 years after the partial test ban as it had in the previous 18 years. “With nuclear testing you were under constant pressure to design a new weapon, engineer it, put it down a hole, blow it up, and then move on to the next one,” says Hugh Gusterson, an anthropologist at the University of British Columbia and an expert on the human factors in nuclear weapons research. “The scientists didn’t have a chance to pause and catch a breath.”

This was, obviously, counter to the spirit of disarmament and reducing the world’s nuclear arsenal, which has been the purported goal of the world’s nuclear states since the 1960s. The tests weren’t about ensuring that America’s nukes still worked or learning about the fundamental physics of the weapon. They were about building bigger and better bombs. “Very few of the tests were reliability tests, where you blow it up to see if it still works,” says Gusterson. “They were almost all tests to develop new designs.”

The US ended all underground nuclear tests in the early 1990s in the lead-up to the Comprehensive Nuclear Test Ban Treaty, despite protests from the heads of the nation’s three national weapons labs—Lawrence Livermore, Sandia, and Los Alamos—who fought “tooth and nail” to prevent the ban, says Gusterson. They were concerned, he says, that a ban would reduce the reliability of America’s nukes and prevent the next generation of nuclear weapons designers and engineers from learning the tools of the trade. But perhaps most importantly, they saw the ban as a threat to the labs’ very existence. All three had been founded to further the development of America’s nuclear arsenal. What was the point of keeping them around if not to blow up their creations?

Mark Chadwick, the chief scientist in the Los Alamos Weapons Physics Directorate, arrived at the national lab in 1990 fresh out of a physics doctoral program at Oxford. At the time, he says, there was a lot of debate among the Los Alamos scientists about the future of the lab, or whether it would have a future at all. “Some thought the labs would really end up struggling to find business and that the nuclear deterrence mission would sort of fade away,” Chadwick recalls. “Overall, the pessimism that the national security mission wouldn’t remain important proved wrong. And fairly quickly, in fact.”

The US conducted its last explosive nuclear test in September, 1992. Today, the nation’s nuclear weapons research is focused on reliability testing and maintenance of the roughly 4,000 active warheads in its arsenal, a program broadly referred to as “stockpile stewardship.” After the test ban, the US government lavished funding on the new stewardship program to keep the nation’s weapons up to snuff. The so-called virtualization of US nuclear tests meant that weapons scientists would employ the most powerful lasers and supercomputers in the world to understand these weapons instead of blowing them up. Physicists at the labs work on the best experimental equipment that money can buy, and their funding has ballooned under the Trump administration. “Business is booming, even without nuclear testing,” says Gusterson.

At the heart of the US stockpile stewardship program is Lawrence Livermore National Laboratory, a sprawling complex across the bay from San Francisco. It’s home to the National Ignition Facility, which uses the most powerful laser in the world to re-create the conditions found in the heart of an exploding nuclear bomb. “It's not so much that it replaces nuclear testing, but it's a very different, richer perspective on what's happening in an operating weapon,” says Kim Budil, principal associate director for the Weapons and Complex Integration directorate at Livermore.

Nuclear tests have always served a variety of purposes. Their primary one, of course, has been deterrence—an ever-increasing show of strength meant to discourage America’s allies from ever hitting the big red button. But even back when the military detonated live nukes, its architects were doing everything they could to figure out exactly what was happening inside. Each bomb was outfitted with tens of millions of dollars worth of sensors designed to capture data in the fraction of a fraction of a second before they were destroyed. Virtualization now allows scientists to dig deeper into the physics of the bomb.

“Over this 25-year stockpile stewardship, we have dramatically increased our knowledge of the fundamental science that's required to do this work,” says Budil “We have types of data and quality of data that were unimaginable during the test era just from the advances in experimental technology.”

The National Ignition Facility at Lawrence Livermore National Laboratory.

Say, for example, physicists at Livermore are interested in how tiny imperfections in materials used in a bomb affect its performance. They can load small samples of the material into target vessels that may just be a few millimeters across. NIF channels an enormous amount of energy into 192 laser beams that are aimed at a target; when they strike, the vessel heats up to more than 5.4 million degrees Fahrenheit. If the vessel is in a type of gold target called a hohlraum, the lasers will cause it to act like an x-ray oven and shock the material inside with a high dose of radiation. Scientists can use an imager to study how the x-rays interact with the material, which is relevant to protect the nukes from certain kinds of missile defense systems.

But the real promise of NIF, says Budil, is that it could set us on the path to fusion energy by way of modeling an exploding nuclear bomb. In this case, the laser’s target is loaded with a diamond capsule filled with a gaseous mixture of two hydrogen isotopes called deuterium and tritium. When the lasers hit the target, the x-rays burn off the capsule’s shell. As that material blows off, it causes the capsule to collapse incredibly fast. For a brief moment, pressures inside the capsule are more than 1 million times greater than the atmospheric pressure on the surface of the Earth. This causes the hydrogen isotopes to fuse together and release a tremendous amount of energy.

The conditions in the target at the moment of fusion—extreme as they are—still pale in comparison to the environment in a thermonuclear bomb at the moment of detonation. To re-create those conditions, Budil says, would take an even stronger laser system. “That was something unique—doing a nuclear test that you could generate these incredibly intense environments,” she says. “We don't have experimental facilities where we have easy access to those conditions.” But by extrapolating from the experimental results in NIF, physicists can still get an unprecedented view of the core of an exploding bomb.

If physicists can sustain that fusion reaction—if they can use lasers to squeeze the hydrogen without letting go—they can get it to release more energy than it took to make the reaction happen. This is called ignition. For the physicists at NIF, achieving ignition would give them a chance to study the conditions of an exploding nuke in detail, and it would also put the world on the path to a virtually unlimited form of clean energy. NIF hasn’t achieved ignition yet, but Budil is optimistic that it’s only a matter of time. “We’re close,” she says.

When they’re not smashing atoms with lasers, scientists at Livermore also conduct what are known as “subcritical tests” at a National Nuclear Security Agency site in the Nevada desert. At BEEF—the Big Explosives Experimental Facility—researchers subject (nonnuclear) materials found in nuclear weapons to extremely powerful conventional explosions to study how they’d respond to an actual nuclear blast. Down the road from BEEF, physicists use a 60-foot, gas-powered gun called Jasper to shoot projectiles at plutonium. These projectiles reach speeds of around 17,000 miles per hour—about 10 times faster than a bullet—and create shock waves as they pass through the barrel. By studying how the plutonium reacts to these pressures and temperatures, physicists can get a better idea of how it will behave inside an exploding nuclear weapon.

The data from these experiments is used to verify the predictions of nuclear weapons simulations cooked up by Livermore’s Sierra supercomputer and to refine the models of the weapon systems that are fed to it. Sierra is the third fastest supercomputer in the world, and Budil says its models are used to understand how changes in the stockpile over time may affect a weapon’s safety or effectiveness. But she cautions that the computer’s models are only as good as its data, which drives physicists at the labs to conduct ever more sophisticated and sensitive experiments.

“The computing machines we’re using today are extraordinary,” says Budil. “But, roughly speaking, they only know what we know. So where there are gaps in our models they won’t give the right answer. We fill that gap with experimental data.”

The Sierra supercomputer at Lawrence Livermore National Laboratory.

Although the primary directive of the US weapons labs is to conduct experiments to ensure the reliable operation of the nation’s nukes, the same facilities can be used to study the scientific problems that have nothing to do with war. Michael Cuneo is the senior manager for the Z machine at Sandia National Laboratory, a singular experimental facility that create conditions found nowhere else on Earth. No more than once per day, massive capacitor banks near the Z facility are charged with a tremendous amount of electricity that is released all at once in a pulse so powerful it causes the ground around the facility to shake. Each shot has 1,000 times the electrical energy of a lightning bolt, and all of it is focused on a target the size of a quarter.

Like NIF, one of the primary goals at Z is to study the fusion reactions that occur when the target implodes at over 3,000 miles per second. But the extreme pressures and temperatures that occur around the target—sometimes in excess of 3 billion degrees Fahrenheit—also make it a great way to study the conditions during a nuclear detonation. Cuneo oversees about 140 shots of the Z machine each year, many of which are used for classified national security experiments. But Cuneo says the Z machine is also regularly used by researchers working on questions about how planets evolve or the processes that power the sun.

“There may be a few shots a year that are really just basic science, and many of the experiments serve a dual use,” says Cuneo, who estimates that approximately 10 percent of the Z machine’s shots are for fundamental science experiments. “But that same experimental platform and the same techniques are also used to investigate the performance of materials that are relevant to nuclear weapons.”

Today, weapons maintenance has superseded weapons development, and the show of strength implicit via nuclear testing has been replaced with a soft power, says Gusterson. He recounts how John Immele, the deputy director of national security at Los Alamos National Lab, made the case in the '90s that the US could flex its nuclear superiority by sending scientists out to give cutting-edge presentations at conferences. This would, presumably, impress upon the world just how well America’s weapons scientists knew their stuff. The implication was that if you messed with America, they’d apply that knowledge to you.

“Nuclear testing not only proof-tested new designs during the Cold War, it also had this sort of signaling function where every time the Earth shook you were signaling what you could do to the other side’s cities,” says Gusterson. “Now you have to find another way of signaling, so you do it with PowerPoint presentations instead.”

But despite nearly global recognition that ending nuclear tests was a good idea, earlier this year the Trump administration floated the idea of resuming explosive nuclear tests. “It’s not something that came out of nowhere,” says Zia Mian, the codirector of Princeton University’s Program on Science and Global Security. Mian points to the influence of Marshall Billingslea, who President Trump recently appointed as the special presidential envoy for arms control, as a key factor. In the 1990s, Billingslea worked for the Republican senator Jesse Helms, who was a vocal opponent of the US signing the Comprehensive Nuclear Test Ban Treaty. “This has been an ongoing recurring effort in Republican administrations by groups of people and institutional interests who are opposed to the very idea of restraint on the US military’s nuclear weapon capabilities,” Mian says.

Mian characterizes the Trump administration’s interest in nuclear testing as a strongman negotiating tactic at a time when economic and political tensions between the US, China, and Russia are at a boiling point. “It's a purely political demonstration of American resolve,” he says. “If the US moves toward testing nuclear weapons as proof of alpha-ness in the international community to satisfy Donald Trump’s ego and to force other people into submission, one can imagine that other countries will find their own ways of demonstrating their own determination not to be bullied through detonating nuclear weapons. That leads to a very dark place in international politics very quickly.”

The irony is that resuming nuclear tests would almost certainly serve the interests of other countries more than it would help the US. Only three countries—India, Pakistan, and North Korea—have conducted explosive nuclear tests since the Comprehensive Nuclear Test Ban Treaty was signed 25 years ago. But if the US were to resume nuclear tests, Mian says, it would effectively be an open invitation for other countries to do the same. The US has conducted hundreds more tests than any other nuclear-armed country, and a couple more won’t drastically improve the way American weapons designers understand these systems. But newer entrants to the nuclear arena, like India and Pakistan, have completed only a few explosive tests, and more testing could help them significantly improve their weapons systems. This, in turn, could kick off a new regional or global nuclear arms race.

“The relative benefit to other countries of resuming testing might be greater than for the US in terms of reliability, confidence, weapon design,” says Mian. “That is a strategic calculation to try and maintain US advantage in comparison to other countries, rather than abandoning nuclear testing as a common good for everybody.”

So until the day comes that the world’s leaders go beyond mere test bans and decide to dismantle their nuclear arsenals, physicists and engineers will continue to toil away out of view of the public eye, creating ever more faithful models of the bombs they are compelled to study, but hope will never be used.

Updated 7-16-20, 11:25 am ET: Kim Budil is the principal associate director for the Weapons and Complex Integration directorate at Livermore, not the director. The number of nuclear tests peaked in 1962, not 1969.

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• HISTORY & CULTURE

U.S. nuclear testing's devastating legacy lingers, 30 years after moratorium

The United States conducted 1,054 atomic tests—costing more than $100 billion and taking an incalculable toll on humans and the environment.

Potassium iodide pills are often given out during nuclear emergencies, actual or imminent. In late August, for example, the European Union pledged to preemptively donate more than five million anti-radiation tablets to Ukraine, amid fears of a Chernobyl-level catastrophe at the Russian-occupied, embattled Zaporizhzhia nuclear power plant.

But for Claudia Peterson, 67, and her peers growing up near Cedar City, Utah, iodide pills were part of their routine—like recess, or homework, or reciting the pledge of allegiance. The ones given to students at her elementary school were big and orange, she recalls.

Another part of the routine: the men in suits who showed up at the school toting Geiger counters. “They would come up to our faces and run this machine over us,” she says. When Peterson asked her teacher what a beeping response from the machine meant, she was told that the device had detected residual radiation from recent dental x-rays.  

“Except,” Peterson says, “I had never had them.”

Formerly an iron mining and agricultural community, Cedar City stands about 175 miles east of the Nevada Test Site, where the United States conducted more than 900 nuclear tests from 1951 through 1992. Others were held across the country, including in Colorado, Alaska, and Mississippi. Tests of the U.S.’s biggest nuclear megaweapons were reserved for sites in the Pacific, including one device in the Marshall Islands a thousand times more powerful than the Hiroshima bomb.

The U.S. carried out its last weapons test on September 23, 1992, with the detonation in Nevada of an approximately 20-kiloton device codenamed Divider. (A kiloton is equivalent to a thousand tons of TNT; the atomic bomb that destroyed Hiroshima was about 15 kilotons.) Just over a week later, on October 2, President George H. W. Bush signed a moratorium on further testing, which has been honored to this day. Now, on the 30th anniversary of that test, National Geographic examines the legacy of U.S. testing in the first half-century of our atomic age.

Before the Nevada tests began, officials told people in Cedar City and other surrounding communities not to worry: There was no danger to anyone beyond the site’s limits, they said. Peterson and her family believed this at first. Yet as fireballs and mushroom clouds kept appearing on the western horizon, it became clear that something was terribly wrong. At a neighboring sheep ranch, “there would be piles of dead lambs,” she says. “Some of them were deformed, with two heads or missing legs.”

Then her schoolmates started getting sick. When she was in sixth grade, she says, a boy one year younger than she died of leukemia. At the same time, another boy around her age got bone cancer and had to have his leg amputated; he died the following year. Just after she graduated from high school, another friend died of liver cancer, Peterson says.

For Peterson and many others, the atomic testing era has never really ended. Many of these “downwinders”—people exposed or likely exposed to radioactive fallout during tests—say that the specter of a possible return to testing someday haunts them. In 2020, when the Washington Post reported that the Trump administration was considering resuming nuclear testing, following unsubstantiated assertions by administration officials that China and Russia were testing low-yield nuclear devices, many in Nevada and Utah decried the decision.

Joe Biden, then a presidential candidate, called the notion “reckless” and “dangerous.” A spokesperson at the National Security Council—chaired now by President Biden—tells National Geographic that “the United States … does not see a need to return to testing” and that the Biden administration calls “on all states possessing nuclear weapons to declare or maintain the zero-yield nuclear explosive testing moratorium.” In the past, Biden has warned that a resumption of U.S. testing might “prompt other countries to resume militarily significant nuclear testing.”  

Experts advise that if a U.S. administration does resume testing, it would risk setting off a new nuclear arms race—as the very first atomic test, in New Mexico, did 77 years ago. During its Cold War nuclear race with the Soviets, the U.S. detonated 1,149 nuclear devices in 1,054 tests—more than those by all seven of the other nuclear-testing nations combined, including the Soviet Union, which conducted more than 700 tests.

In the U.S.’s bid for nuclear supremacy, populations in the vicinity of test sites became collateral damage from radioactive fallout. Officials in charge of the tests also courted environmental and geological catastrophes, including possible earthquakes, tidal waves, dam breaks, and more.

The decision makers “were cavalier by today’s standards,” says nuclear weapons historian Alex Wellerstein . “Today, we say, ‘If you don’t know it’s safe, don’t do it.’ But back then, they leaned toward doing it anyway.” It was a question, he adds, of political priorities. Cold War leaders believed that testing was an existential necessity and that greater harm would come from not testing as the Soviets continued to build their own atomic arsenal.

“The tricky part,” Wellerstein adds, “is that they didn’t give a voice to the people who were going to be at risk.”

The testing program easily cost taxpayers more than $100 billion in fiscal 2023 dollars, according to Stephen Schwartz, nonresident senior fellow at the Bulletin of the Atomic Scientists.   Total spending on U.S. nuclear weapons and weapons-related programs “now exceeds $10 trillion and counting,” he says.

The human costs, however, are incalculable.

‘Now, I am become Death’

  In the middle of the night on July 16, 1945, a caravan of buses, cars, and trucks carried about 90 scientists to the Alamogordo Bombing Range—a desert testing ground 125 miles southeast of Albuquerque, New Mexico. Among them was William “Atomic Bill” Laurence, a New York Times reporter conscripted earlier that year as the in-house historian and propagandist of the Manhattan Project. Just before dawn, the team would attempt to detonate an atomic bomb for the first time.  

As some from the group picnicked and passed around “sunburn lotion,” they fretted about whether the years and billions of dollars spent on the top-secret project would work. (Manhattan Project physicists had also deliberated—and placed bets—on whether the bomb might set the Earth’s atmosphere on fire but decided it would be unlikely.)

At 5:30 a.m., the team detonated a 21-kiloton plutonium implosion device nicknamed Gadget atop a hundred-foot tower. The blast—which packed an explosive payload equivalent of about 21,000 tons of TNT—dredged up and irradiated hundreds of tons of soil and sent a mushroom cloud up to 70,000 feet high. For Laurence, the explosion was unlike anything ever seen on the planet: It had the “light of many super-suns” and was “devastating, full of great promise and great forebodings,” he wrote. For physicist and “father of the atomic bomb” J. Robert Oppenheimer, it brought to mind Hindu scripture: “Now, I am become Death, the Destroyer of Worlds.” Everyone there knew, he said later, that “the world would not be the same.”

Some residents of the surrounding areas thought they were witnessing the end of the world. The flash was so bright that a blind girl a hundred miles away saw it, according to one local press report. Within hours, an odd, snow-like ash blanketed the nearby countryside. Fallout was detected as far away as New York State.

None of those living near the Trinity site were warned or evacuated before or after the blast. It had been selected in part for its supposed remoteness from human settlement, but census data from 1940 show that nearly half a million people in New Mexico, Texas, and Mexico lived within 150 miles of ground zero. (Privately acknowledging the “very serious hazard” posed by the blast, the Manhattan Project’s chief medical officer advised that future tests should likely only be conducted where no one lived within a 150-mile radius.) To calm nerves, officials told people that a nearby ammunition dump had exploded. Many learned the truth about the blast only years later, and Trinity test survivors are not among the downwinders eligible for government compensation.

Upon learning of the first successful American nuclear test, the Soviet Union accelerated efforts to develop their own bomb. The Soviets successfully tested their first device in 1949, ending the U.S.’s nuclear monopoly and setting off an international nuclear arms race.

‘Who does this to their own people?’

On January 11, 1951, the U.S. Atomic Energy Commission distributed a handbill to residents of towns and farming communities in southern Nevada and Utah, announcing that it would soon start testing nuclear bombs nearby. Tests would go on indefinitely at what would become known as the Nevada Test Site, 65 miles north of Las Vegas, but there would be no danger to people beyond the perimeter, it said.

Sixteen days later, a B-50 bomber dropped Able, a one-kiloton bomb, over the test site—the first of a hundred aboveground bombs detonated there during the next decade.

For nearby residents, the blasts became a regular occurrence and even, at first, a form of entertainment. And soon, Americans across the country could occasionally experience the bombs voyeuristically on national television, including the 1953 Annie test, whose 16-kiloton blast dramatically incinerated a mock neighborhood dubbed Doom Town, complete with cars and suburban homes filled with furniture and mannequins arranged in various activities.  

Officials assured those living around the site that the detonations were “relatively small in explosive power,” but some blasts were enormous: Hood was a 74-kiloton bomb exploded in 1957 as part of a larger military exercise in a nearby field involving 2,200 U.S. Marines. In 1962, the 104-kiloton Sedan test—seven times as powerful as the Hiroshima bomb—displaced more than 12 million tons of earth and left a hole 1,280 feet wide and 320 feet deep. It has the distinction of being the largest manmade crater in the U.S., and the Nevada Test Site’s Yucca Flat testing region remains the most cratered landscape on the planet, according to the U.S. Department of the Interior .

Tests were conducted on days when winds were projected to blow fallout clouds to the east and northeast—away from Las Vegas, which enjoyed a financial boom from the new nuclear enterprise. Opportunistic business owners turned the detonations into Vegas attractions: Bars concocted atomic-themed cocktails, casinos hosted “dawn parties” at which guests could watch the explosions.

By the late 1950s, enthusiasm for atomic partying was waning fast, as the extent and effects of testing contamination became painfully clear—even as the government attempted to put a positive spin on the situation. In 1955, a U.S. Atomic Energy Commission test manager issued an announcement to those living in communities surrounding the Nevada test site, thanking them for being “active participants” in the program, for their patriotism, and for their stoicism. They’d been exposed to risks from the test flashes, blasts, and fallout but were to be commended for “accept[ing] the inconvenience … without fuss, without alarm, and without panic.” The free world was safer as a result of their sacrifices, they were told.

“We were very trusting, patriotic, family-oriented people,” Claudia Peterson says. “My biggest fear back then was Russia, and what it was going to do to us. Yet it was my own government that was killing my family and my neighbors and my friends. Who does this to their own people?”

Peterson’s father, Ralph Boshell, had a brain tumor the size of a lemon removed and died six months after the operation at age 64, she says. Her sister, Cathy Orton, died of melanoma at 36, leaving behind six children. (She delivered her last baby while she was “full of cancer,” Peterson says.) Peterson’s daughter Bethany was diagnosed with stage 4 neuroblastoma when she was three; she died of acute monoblastic leukemia three years later at age six.

“This testing created a very dangerous environment all across the country,” says Lilly Adams, founder of Nuclear Voices and Senior Outreach Coordinator at the Union of Concerned Scientists. “The Nevada tests created hot spots as far away as Indiana and New York,” she says. Fallout on fields and grazing land led to contaminated milk supplies. “People most at risk were families and especially children who were drinking milk from local farms and dairies.”

Authors of a study published in 1990 in the Journal of the American Medical Association   found nearly eight times more leukemia in children under 19 who lived in southwestern Utah during the aboveground testing. Later that decade, a National Cancer Institute study concluded that aboveground testing in Nevada may have produced as many as 212,000 “excess lifetime cases” of thyroid cancer, although Adams says some experts suggested that might be an undercount. Yet another study, conducted jointly in 2005 by the Centers for Disease Control and Prevention and the National Cancer Institute, found that any person living in the contiguous United States since 1951 has been exposed to radioactive fallout from testing.

In 1963, President John F. Kennedy signed a moratorium on atmospheric testing, along with the United Kingdom and Soviet Union. Underground tests were still permissible, however, and the U.S. ultimately conducted 828 at the Nevada Test Site. Although mostly contained underground, radioactive contamination sometimes vented from subterranean detonation caverns.

Conceding at last the consequences to humans of aboveground testing, Congress in 1990 passed the first iteration of the Radiation Exposure Compensation Act for “downwinders” in designated geographic areas suffering as the result of possible exposure to fallout from leukemia, multiple myeloma, lymphomas, or one or more of 16 different cancers.

The act, updated in 2000 and extended earlier this year, has distributed more than $2 billion to downwinders and workers at nuclear sites. Previously ineligible downwinders—including those affected by the Trinity test—are campaigning urgently for inclusion . Claudia Peterson is among those who say the act’s recognition and compensation are insufficient for covering medical costs—and paltry compared to nuclear weapons budgets. “No amount of money can compensate for watching a child die,” she says.

Wellerstein and other experts say that if the U.S. ever does resume nuclear testing, it would likely take place at the former Nevada Testing Site, now renamed the Nevada National Security Site.

Vaporized islands and ‘jellyfish babies’

Tests of the U.S.’s biggest thermonuclear bombs—hugely powerful weapons also known as hydrogen bombs or H-bombs—were reserved for the Pacific Proving Grounds, located largely in the Marshall Islands, some 2,400 miles west of Hawaii. The first U.S. H-bomb—codenamed Ivy Mike, with an explosive payload of 10.4 megatons, nearly 700 times that of the Hiroshima bomb—was detonated in 1952. It vaporized the small island of Elugelab, leaving a crater more than a mile long and 164 feet deep.

Then came Castle Bravo, in 1954, a 15-megaton hydrogen bomb exploded at Bikini Atoll. A bomb that size detonated over New York City would cause up to five million deaths and create a fireball nearly two miles wide, according to NukeMap . (In 1961, the Soviets detonated their largest thermonuclear weapon, the 50-megaton Tsar Bomba, which had “roughly 10 times the total explosive power unleashed in all of World War II, including both the Little Boy and Fat Man bombs that destroyed Hiroshima and Nagasaki,” according to nuclear expert Sara Kutchesfahani.)

“These multimegaton weapons [were] very dirty in terms of their fallout content,” Wellerstein says. Clouds from Ivy Mike and Castle Bravo were closely monitored, he adds, “and they went around the entire world over the course of a week or so.” Contamination spread over roughly 7,000 square miles —“the worst radiological disaster in U.S. history ,” according to the Atomic Heritage Foundation.

Fallout landed most heavily on surrounding atolls to the east and southeast of Bikini. Marshallese on Bikini and Enewetak atolls had been relocated before the tests, some to Rongelap Atoll 160 miles away from Bikini. Lijon Eknilang, then an eight-year-old living on Rongelap, witnessed Castle Bravo and in a 2003 testimony recalled the blinding flash and swaying ground. “We were very afraid because we didn’t know what it was,” she said. “The elders said another world war had begun.”

Soon came the telltale cloud, and an hours-long flurry of radioactive debris blanketed Rongelap. Water in containment drums began to change color, “but we drank it anyway, Eknilang said. Then radiation sickness set in: People began vomiting, blistering, and losing hair. Two days later, the U.S. military evacuated 64 Marshallese from Rongelap to a U.S. base on Kwajalein Atoll for medical treatment.

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They were allowed to return to Rongelap in 1957 “under continuing radiological surveillance,” according to a 1994 report National Research Council Committee on Radiological Safety in the Marshall Islands. “Later … unanticipated medical problems began to surface,” the report went on.

Eknilang described the illnesses: cancers, leukemias, still births, thyroid tumors, and “jellyfish babies”—infants born without bones and with transparent skin, who usually died within a day or two. Eknilang said she had suffered seven miscarriages and various cancers; she died in 2012. In 1985, the Rongelap people left the island again, relocating to Mejatto Island, on Kwajalein Atoll.

During the late 1970s, the U.S. government built an aboveground, concrete-covered nuclear waste storage site—Runit Dome—about 350 miles away on Runit Island, in Enewetak Atoll. Marshallese call it “the tomb.” The U.S. Department of Energy—successor to the Atomic Energy Commission—oversaw radiological cleanup of Enewetak , done by a workforce of more than 4,000 U.S. servicemen. They loaded the containment unit with more than three million cubic feet (equivalent to 35 Olympic-size swimming pools) of hazardous radioactive test waste; Runit Dome also holds 130 tons of contaminated soil brought from the Nevada Test Site, according to a 2019 Los Angeles Times   report . Some veterans who worked on the cleanup say they were unaware that they were working with radioactive materials and were not adequately protected .

Local leaders and experts fear that the dome is threatened by rising seas. In 2015, Tony du Brum—a Castle Bravo survivor and later the foreign minister and minister of health and the environment of the Marshall Islands— called Runit Dome “a cracking concrete crater of nuclear waste slowly leaking into the lagoon—for which my struggling nation has no capacity but has apparently inherited.”

In 2020, however, a Department of Energy report to Congress stated that the “containment structure is still serving its intended purpose” and that “the dome is not in any immediate danger of collapse or failure.” According to the State Department, the U.S. has provided more than $600 million to Marshallese communities affected by nuclear tests.

Blasts on the Ring of Fire

Amchitka Island—near the western end of the Aleutian Island chain, about 1,300 miles west-southwest of Anchorage—sits squarely within the Ring of Fire . This 25,000-mile tectonically active zone along the periphery of the Pacific Ocean is the site of 90 percent of earthquakes and the most violent seismic events recorded on Earth. During the 1960s and early 70s, the U.S. carried out three massive underground tests there. The first, Long Shot, in 1965, was more than five times as powerful as the Hiroshima bomb. The second, Milrow, in 1969, packed more than 10 times the power of Long Shot.

Next came five-megaton Cannikin, a thermonuclear device with an explosive payload 333 times more powerful than the Hiroshima bomb that spurred anger and controversy ahead of its scheduled 1971 detonation. Opponents feared that its subterranean explosion might trigger a major earthquake and calamitous tsunami. Protesters rallied in front of the White House; more than 30 senators called on then President Richard Nixon to halt the test; the Japanese government objected for fear of a tsunami.

“The risks are so great, the gains so dubious, and the debits already so real that the entire experiment appears to be a ghastly and unnecessary mistake,” a New York Times editorial declared.

Atomic Energy Commission officials downplayed the dangers but acknowledged privately that “the worst conceivable effects of Cannikin … cannot be ruled out.” A coalition of environmental groups launched a Hail Mary legal challenge to the test that went up to the Supreme Court. Convening on a day’s notice for a rare Saturday morning session, the court denied the injunction.  

Cannikin—the largest-ever U.S. underground detonation—took place on November 6, 1971, heaving the surrounding earth up some 20 feet and creating a shock equivalent to a 7.0 earthquake on the Richter scale. No seismic disaster followed, but Cannikin was seen as a turning point, igniting citizen outrage over “unchecked freedom with which [atomic] weapons are commissioned, tested, and deployed,” as Time magazine put it at the time.

Radioactive material remains sealed in the test cavities “because no practicable technology exists to remove [it],” according to the Department of Energy , whose Office of Legacy Management continues to monitor seismic activity that might affect the site.

Nuclear fracking

Not all U.S. nuclear detonations were weapons tests; some were intended to find out if nuclear energy and atomic blasts had industrial applications. Gnome, an underground test in 1961 near Carlsbad, New Mexico, was held to determine whether nuclear-blast energy could be converted into electricity. Six years later came Gasbuggy, near Farmington, New Mexico, to explore whether underground atomic detonations could stimulate release of subterranean natural gas. Gasbuggy did release gas, but it was irradiated in the explosion, making it commercially unusable.

Despite this discouraging result, in 1969, the U.S. conducted another nuclear fracking test, near Parachute, Colorado. As with Gasbuggy, radioactivity from the 40-kiloton Rulison explosion contaminated the gas it released, rendering it useless. The next scheduled underground test in Colorado prompted protests and a class action lawsuit filed by a coalition of environmental groups. Yet on May 17, 1973, the Rio Blanco test went ahead anyway, with three simultaneous underground detonations near Meeker. This trio of blasts—also a “natural gas reservoir stimulation” experiment—had a combined explosive payload of 99 kilotons, nearly seven times that of the Hiroshima bomb.

The next year, Coloradans approved a state constitutional amendment requiring voter approval before any atomic detonation could be conducted. The Office of Legacy Management says that the Rulison and Rio Blanco sites are monitored annually for leaked radioactive and hazardous materials, and drilling in the immediate area of the test sites is prohibited.  

‘Everyone’s wells went bad’

After the 1963 moratorium on aboveground nuclear tests, officials began to anticipate the possibility that underground tests also might be banned someday. To determine whether other nuclear powers might be able to carry out covert underground tests, the U.S. started conducting subterranean tests to figure out whether seismic equipment could detect faraway nuclear blasts below ground.  

A subterranean salt dome near Purvis, Mississippi, about 20 miles southwest of Hattiesburg, made an ideal test location—an underground structure that might effectively muffle the sound of an atomic explosion.  

On October 22, 1964, the Atomic Energy Commission and Department of Defense detonated a 5.3-kiloton device dubbed Salmon 2,710 feet down inside the dome. Nearby residents had been evacuated and compensated $10 per adult and $5 per child for the inconvenience. Salmon’s explosion registered 6.0 on the Richter scale and was detected as far away as Sweden; its shockwave lifted the ground four inches and blasted a cavity deep inside the salt dome. Two years later, a smaller nuclear device, Sterling, was detonated in that same space—and this time, the cavity created by the previous blast muffled the explosion, proving that nuclear powers indeed could try to hide tests by detonating atomic devices inside similar underground caverns.

Hundreds of Mississippians in the vicinity reported blast damage, especially from Salmon, to their homes and properties. “Everybody’s wells went bad,” Purvis resident Tom Beshears recalled in a 2014 interview . Public concerns surfaced about health problems possibly related to the tests. In 2000, the U.S. government commissioned a pipeline to bring clean water far from the site so people wouldn’t have to rely on local well water, and in 2015, the federal government paid $16.8 million in settlements to workers employed at the test site or living nearby.

What does the future hold?

Since 1992, the nine nuclear nations largely have honored the testing moratorium. (North Korea remains the exception, having conducted six tests since 2006; India and Pakistan both tested nuclear weapons in 1998.) To date, 186 nations have signed the Comprehensive Nuclear Test Ban Treaty prohibiting any nuclear detonations. The U.S. has not yet ratified it; Russia ratified it in 2000.

The entire U.S. nuclear stockpile is reviewed annually, mainly through “subcritical” tests—blasts that don’t produce a nuclear chain reaction but still test weapon components—and computer simulations. The Stockpile Stewardship Program “has done an amazingly good job,” says Robert Rosner, former chief scientist and director of the Department of Energy’s Argonne National Laboratory.

Yet the possibility that some part of the current testing program might fail, or that a future U.S. administration might resume full-blast testing for political or military reasons, triggers anxiety in testing-era downwinder communities.

“When they talk about reinvigorating the testing program, I want to know: Who is going to accept that in their backyards?” says Tina Cordova, a downwinder activist, cancer survivor, and fifth-generation resident of Tularosa, New Mexico, about 40 miles from the Trinity test site. Generations of her family have now suffered from testing-related cancers and health problems, she says.

“No test is void of risk and danger, and somebody is going to suffer the consequences of that,” she adds. “I just ask: Are you willing to stake your future on that, and the future of your family?”

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Nuclear Tests Marked Life on Earth With a Radioactive Spike

Even as it disappears, the “bomb spike” is revealing the ways humans have reshaped the planet.

O n the morning of March 1, 1954, a hydrogen bomb went off in the middle of the Pacific Ocean. John Clark was only 20 miles away when he issued the order, huddled with his crew inside a windowless concrete blockhouse on Bikini Atoll. But seconds went by, and all was silent. He wondered if the bomb had failed. Eventually, he radioed a Navy ship monitoring the test explosion.

“It’s a good one,” they told him.

Then the blockhouse began to lurch. At least one crew member got seasick—“landsick” might be the better descriptor. A minute later, when the bomb blast reached them, the walls creaked and water shot out of the bathroom pipes. And then, once more, nothing. Clark waited for another impact—perhaps a tidal wave—but after 15 minutes he decided it was safe for the crew to venture outside.

The mushroom cloud towered into the sky. The explosion, dubbed “Castle Bravo,” was the largest nuclear-weapons test up to that point. It was intended to try out the first hydrogen bomb ready to be dropped from a plane. Many in Washington felt that the future of the free world depended on it, and Clark was the natural pick to oversee such a vital blast. He was the deputy test director for the Atomic Energy Commission, and had already participated in more than 40 test shots. Now he gazed up at the cloud in awe. But then his Geiger counter began to crackle.

“It could mean only one thing,” Clark later wrote. “We were already getting fallout.”

That wasn’t supposed to happen. The Castle Bravo team had been sure that the radiation from the blast would go up to the stratosphere or get carried away by the winds safely out to sea. In fact, the chain reactions unleashed during the explosion produced a blast almost three times as big as predicted—1,000 times bigger than the Hiroshima bomb.

Within seconds, the fireball had lofted 10 million tons of pulverized coral reef, coated in radioactive material. And soon some of that deadly debris began dropping to Earth. If Clark and his crew had lingered outside, they would have died in the fallout.

Clark rushed his team back into the blockhouse, but even within the thick walls, the level of radiation was still climbing. Clark radioed for a rescue but was denied: It would be too dangerous for the helicopter pilots to come to the island. The team hunkered down, wondering if they were being poisoned to death. The generators failed, and the lights winked out.

“We were not a happy bunch,” Clark recalled.

They spent hours in the hot, radioactive darkness until the Navy dispatched helicopters their way. When the crew members heard the blades, they put on bedsheets to protect themselves from fallout. Throwing open the blockhouse door, they ran to nearby jeeps as though they were in a surreal Halloween parade, and drove half a mile to the landing pad. They clambered into the helicopters, and escaped over the sea.

Read: The people who built the atomic bomb

As Clark and his crew found shelter aboard a Navy ship, the debris from Castle Bravo rained down on the Pacific. Some landed on a Japanese fishing boat 70 miles away. The winds then carried it to three neighboring atolls. Children on the island of Rongelap played in the false snow. Five days later, Rongelap was evacuated, but not before its residents had received a near-lethal dose of radiation. Some people suffered burns, and a number of women later gave birth to severely deformed babies. Decades later, studies would indicate that the residents experienced elevated rates of cancer.

The shocking power of Castle Bravo spurred the Soviet Union to build up its own nuclear arsenal, spurring the Americans in turn to push the arms race close to global annihilation. But the news reports of sick Japanese fishermen and Pacific islanders inspired a worldwide outcry against bomb tests. Nine years after Clark gave the go-ahead for Castle Bravo, the United States, Soviet Union, and Great Britain signed a treaty to ban aboveground nuclear-weapons testing. As for Clark, he returned to the United States and lived for another five decades, dying in 2002 at age 98.

Among the isotopes created by a thermonuclear blast is a rare, radioactive version of carbon, called carbon 14. Castle Bravo and the hydrogen-bomb tests that followed it created vast amounts of carbon 14, which have endured ever since. A little of this carbon 14 made its way into Clark’s body, into his blood, his fat, his gut, and his muscles. Clark carried a signature of the nuclear weapons he tested to his grave.

I can state this with confidence, even though I did not carry out an autopsy on Clark. I know this because the carbon 14 produced by hydrogen bombs spread over the entire world. It worked itself into the atmosphere, the oceans, and practically every living thing. As it spread, it exposed secrets. It can reveal when we were born. It tracks hidden changes to our hearts and brains. It lights up the cryptic channels that join the entire biosphere into a single network of chemical flux. This man-made burst of carbon 14 has been such a revelation that scientists refer to it as “the bomb spike.” Only now is the bomb spike close to disappearing, but as it vanishes, scientists have found a new use for it: to track global warming, the next self-inflicted threat to our survival.

S ixty-five years after Castle Bravo, I wanted to see its mark. So I drove to Cape Cod, in Massachusetts. I was 7,300 miles from Bikini Atoll, in a cozy patch of New England forest on a cool late-summer day, but Clark’s blast felt close to me in both space and time.

I made my way to the Woods Hole Oceanographic Institute, where I met Mary Gaylord, a senior research assistant. She led me to the lounge of Maclean Hall. Outside the window, dogwoods bloomed. Next to the Keurig coffee maker was a refrigerator with the sign that read STORE ONLY FOOD IN THIS REFRIGERATOR . We had come to this ordinary spot to take a look at something extraordinary. Next to the refrigerator was a massive section of tree trunk, as wide as a dining-room table, resting on a pallet.

The beech tree from which this slab came from was planted around 1870, by a Boston businessman named Joseph Story Fay near his summer house in Woods Hole. The seedling grew into a towering, beloved fixture in the village. Lovelorn initials scarred its broad base. And then, after nearly 150 years, it started to rot from bark disease and had to come down.

“They had to have a ceremony to say goodbye to it. It was a very sad day,” Gaylord said. “And I saw an opportunity.”

Gaylord is an expert at measuring carbon 14. Before the era of nuclear testing, carbon 14 was generated outside of labs only by cosmic rays falling from space. They crashed into nitrogen atoms, and out of the collision popped a carbon 14 atom. Just one in 1 trillion carbon atoms in the atmosphere was a carbon 14 isotope. Fay’s beech took carbon dioxide out of the atmosphere to build wood, and so it had the same one-in-a-trillion proportion.

When Gaylord got word that the tree was coming down in 2015, she asked for a cross-section of the trunk. Once it arrived at the institute, she and two college students carefully counted its rings. Looking at the tree, I could see a line of pinholes extending from the center to the edge of the trunk. Those were the places where Gaylord and her students used razor blades to carve out bits of wood. In each sample, they measured the level of radiocarbon.

“In the end, we got what I hoped for,” she said. What she’d hoped for was a history of our nuclear era.

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What Lies Beneath

For most of the tree’s life, they found, the level had remained steady from one year to the next. But in 1954, John Clark initiated an extraordinary climb. The new supply of radiocarbon atoms in the atmosphere over Bikini Atoll spread around the world. When it reached Woods Hole, Fay’s beech tree absorbed the bomb radiocarbon in its summer leaves and added it to its new ring of wood.

As nuclear testing accelerated, Fay’s beech took on more radiocarbon. A graph pinned to the wall above the beech slab charts the changes. In less than a decade, the level of radiocarbon in the tree’s outermost rings nearly doubled to almost two parts per trillion. But not long after the signing of the Partial Test Ban Treaty in 1963, that climb stopped. After a peak in 1964, each new ring of wood in Fay’s beech carried a little less radiocarbon. The fall was far slower than the climb. The level of radiocarbon in the last ring the beech grew before getting cut down was only 6 percent above the radiocarbon levels before Castle Bravo. Versions of the same sawtoothlike peak Gaylord drew had already been found in other parts of the world, including the rings of trees in New Zealand and the coral reefs of the Galapagos Islands. In October 2019, Gaylord unveiled an exquisitely clear version of the bomb spike in New England.

W hen scientists first discovered radiocarbon, in 1940, they did not find it in a tree or any other part of nature. They made it. Regular carbon has six protons and six neutrons. At UC Berkeley, Martin Kamen and Sam Ruben blasted carbon with a beam of neutrons and produced a new form, with eight neutrons instead of six. Unlike regular carbon, these new atoms turned out to be a source of radiation. Every second, a small portion of the carbon 14 atoms decayed into nitrogen, giving off radioactive particles. Kamen and Ruben used that rate of decay to estimate carbon 14’s half-life at 4,000 years. Later research would sharpen that estimate to 5,700 years.

Soon after Kamen and Ruben’s discovery, a University of Chicago physicist named Willard Libby determined that radiocarbon existed beyond the walls of Berkeley’s labs. Cosmic rays falling from space smashed into nitrogen atoms in the atmosphere every second of every day, transforming those atoms into carbon 14. And because plants and algae drew in carbon dioxide from the air, Libby realized, they should have radiocarbon in their tissue, as should the animals that eat those plants (and the animals that eat those animals, for that matter).

Libby reasoned that as long as an organism is alive and taking in carbon 14, the concentration of the isotope in its tissue should roughly match the concentration in the atmosphere. Once an organism dies, however, its radiocarbon should decay and eventually disappear completely.

To test this idea, Libby set out to measure carbon 14 in living organisms. He had colleagues go to a sewage-treatment plant in Baltimore, where they captured the methane given off by bacteria feeding on the sewage. When the methane samples arrived in Chicago, Libby extracted the carbon and put it in a radioactivity detector.. It crackled as carbon 14 decayed to nitrogen.

Read: Global warming could make carbon dating impossible

To see what happens to carbon 14 in dead tissue, Libby ran another experiment, this one with methane from oil wells. He knew that oil is made up of algae and other organisms that fell to the ocean floor and were buried for millions of years. Just as he had predicted, the methane from ancient oil contained no carbon 14 at all.

Libby then had another insight, one that would win him the Nobel Prize: The decay of carbon 14 in dead tissues acts like an archaeological clock. As the isotope decays inside a piece of wood, a bone, or some other form of organic matter, it can tell scientists how long ago that matter was alive. Radiocarbon dating, which works as far back as about 50,000 years, has revealed to us to when the Neanderthals became extinct, when farmers domesticated wheat, when the Dead Sea Scrolls were written. It has become the calendar of humanity.

Word of Libby’s breakthrough reached a New Zealand physicist named Athol Rafter. He began using radiocarbon dating on the bones of extinct flightless birds and ash from ancient eruptions. To make the clock more precise, Rafter measured the level of radiocarbon in the atmosphere. Every few weeks he climbed a hill outside the city of Wellington and set down a Pyrex tray filled with lye to trap carbon dioxide.

Rafter expected the level of radiocarbon to fluctuate. But he soon discovered that something else was happening: Month after month, the carbon dioxide in the atmosphere was getting more radioactive. He dunked barrels into the ocean, and he found that the amount of carbon 14 was rising in seawater as well. He could even measure extra carbon 14 in the young leaves growing on trees in New Zealand.

The Castle Bravo test and the ones that followed had to be the source. They were turning the atmosphere upside down. Instead of cosmic rays falling from space, they were sending neutrons up to the sky, creating a huge new supply of radiocarbon.

In 1957, Rafter published his results in the journal Science . The implications were immediately clear—and astonishing: Man-made carbon 14 was spreading across the planet from test sites in the Pacific and the Arctic. It was even passing from the air into the oceans and trees.

Other scientists began looking, and they saw the same pattern. In Texas, the carbon 14 levels in new tree rings were increasing each year. In Holland, the flesh of snails gained more as well. In New York, scientists examined the lungs of a fresh human cadaver, and found that extra carbon 14 lurked in its cells. A living volunteer donated blood and an exhalation of air. Bomb radiocarbon was in those, too.

Bomb radiocarbon did not pose a significant threat to human health—certainly not compared with other elements released by bombs, such as plutonium and uranium. But its accumulation was deeply unsettling nonetheless. When Linus Pauling accepted the 1962 Nobel Peace Prize for his campaigning against hydrogen bombs, he said that carbon 14 “deserves our special concern” because it “shows the extent to which the earth is being changed by the tests of nuclear weapons.”

Photos: When we tested nuclear bombs

The following year, the signing of the Partial Test Ban Treaty stopped aboveground nuclear explosions, and ended the supply of bomb radiocarbon. All told, those tests produced about 60,000 trillion trillion new atoms of carbon 14. It would take cosmic rays 250 years to make that much. In 1964, Rafter quickly saw the treaty’s effect: His trays of lye had less carbon 14 than they had the year before.

O nly a tiny fraction of the carbon 14 was decaying into nitrogen. For the most part, the atmosphere’s radiocarbon levels were dropping because the atoms were rushing out of the air. This exodus of radiocarbon gave scientists an unprecedented chance to observe how nature works.

Today scientists are still learning from these man-made atoms. “I feel a little bit bad about it,” says Kristie Boering, an atmospheric chemist at UC Berkeley who has studied radiocarbon for more than 20 years. “It’s a huge tragedy, the fact that we set off all these bombs to begin with. And then we get all this interesting scientific information from it for all these decades. It’s hard to know exactly how to pitch that when we’re giving talks. You can’t get too excited about the bombs that we set off, right?”

Yet the fact remains that for atmospheric scientists like Boering, bomb radiocarbon has lit up the sky like a tracer dye. When nuclear triggermen such as John Clark set off their bombs, most of the resulting carbon 14 shot up into the stratosphere directly above the impact sites. Each spring, parcels of stratospheric air gently fell down into the troposphere below, carrying with them a fresh load of carbon 14. It took a few months for these parcels to settle on weather stations on the ground. Only by following bomb radiocarbon did scientists discover this perpetual avalanche.

Once carbon 14 fell out of the stratosphere, it kept moving. The troposphere is made up of four great rings of circulating air. Inside each ring, warm air rises and flows through the sky away from the equator. Eventually it cools and sinks back to the ground, flowing toward the equator again before rising once more. At first, bomb radiocarbon remained trapped in the Northern Hemisphere rings, above where the tests had taken place. It took many years to leak through their invisible walls and move toward the tropics. After that, the annual monsoons sweeping through southern Asia pushed bomb radiocarbon over the equator and into the Southern Hemisphere.

Eventually, some of the bomb radiocarbon fell all the way to the surface of the planet. Some of it was absorbed by trees and other plants, which then died and delivered some of that radiocarbon to the soil. Other radiocarbon atoms settled into the ocean, to be carried along by its currents.

Carbon 14 “is inextricably linked to our understanding of how the water moves,” says Steve Beaupre, an oceanographer at Stony Brook University, in New York.

In the 1970s, marine scientists began carrying out the first major chemical surveys of the world’s oceans. They found that bomb radiocarbon had penetrated the top 1,000 meters of the ocean. Deeper than that, it became scarce. This pattern helped oceanographers figure out that the ocean, like the atmosphere above, is made up of layers of water that remain largely separate.

The warm, relatively fresh water on the surface of the ocean glides over the cold, salty depths. These surface currents become saltier as they evaporate, and eventually, at a few crucial spots on the planet, these streams get so dense that they fall to the bottom of the ocean. The bomb radiocarbon from Castle Bravo didn’t start plunging down into the depths of the North Atlantic until the 1980s, when John Clark was two decades into retirement. It’s still down there, where it will be carried along the seafloor by bottom-hugging ocean currents for hundreds of years before it rises to the light of day.

Some of the bomb radiocarbon that falls into the ocean makes its way into ocean life, too. Some corals grow by adding rings of calcium carbonate, and they have recorded their own version of the bomb spike. Their spike lagged well behind the one that Rafter recorded, thanks to the extra time the radiocarbon took to mix into the ocean. Algae and microbes on the surface of the ocean also take up carbon from the air, and they feed a huge food web in turn. The living things in the upper reaches of the ocean release organic carbon that falls gently to the seafloor—a jumble of protoplasmic goo, dolphin droppings, starfish eggs, and all manner of detritus that scientists call marine snow. In recent decades, that marine snow has become more radioactive.

In 2009, a team of Chinese researchers sailed across the Pacific and dropped traps 36,000 feet down to the bottom of the Mariana Trench. When they hauled the traps up, there were minnow-size, shrimplike creatures inside. These were Hirondellea gigas , a deep-sea invertebrate that forages on the seafloor for bits of organic carbon. The animals were flush with bomb radiocarbon—a puzzling discovery, because the organic carbon that sits on the floor of the Mariana Trench is thousands of years old. It was as if they had been dining at the surface of the ocean, not at its greatest depths. In a few of the Hirondellea , the researchers found undigested particles of organic carbon. These meals were also high in carbon 14.

Read: A troubling discovery in the deepest ocean trenches

The bomb radiocarbon could not have gotten there by riding the ocean’s conveyor belt, says Ellen Druffel, a scientist at UC Irvine who collaborated with the Chinese team. “The only way you can get bomb carbon by circulation down to the deep Pacific would take 500 years,” she says. Instead, Hirondellea must be dining on freshly fallen marine snow.

“I must admit, when I saw the data it was really amazing,” Dreffel says. “These organisms were sifting out the very youngest material from the surface ocean. They were just leaving behind everything else that came down.”

M ore than 60 years have passed since the peak of the bomb spike, and yet bomb radiocarbon is telling us new stories about the world. That’s because experts like Mary Gaylord are getting better at gathering these rare atoms. At Woods Hole, Gaylord works at the National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS for short). She prepares samples for analysis in a thicket of pipes, wires, glass tubes, and jars of frothing liquid nitrogen. “Our whole life is vacuum lines and vacuum pumps,” she told me.

At NOSAMS, Gaylord and her colleagues measure radiocarbon in all manner of things: sea spray, bat guano, typhoon-tossed trees. The day I visited, Gaylord was busy with fish eyes. Black-capped vials sat on a lab bench, each containing a bit of lens from a red snapper.

The wispy, pale tissue had come to NOSAMS from Florida. A biologist named Beverly Barnett had gotten hold of eyes from red snapper caught in the Gulf of Mexico and sliced out their lenses. Barnett then peeled away the layers of the lenses one at a time. When she describes this work, she makes it sound like woodworking or needlepoint—a hobby anyone would enjoy. “It’s like peeling off the layers of an onion,” she told me. “It’s really nifty to see.”

Eventually, Barnett made her way down to the tiny nub at the center of each lens. These bits of tissue developed when the red snapper were still in their eggs. And Barnett wanted to know exactly how much bomb radiocarbon is in these precious fragments. In a couple of days, Gaylord and her colleagues would be able to tell her.

Gaylord started by putting the lens pieces into an oven that slowly burned them away. The vapors and smoke flowed into a pipe, chased by helium and nitrogen. Gaylord separated the carbon dioxide from the other compounds, and then shunted it into chilled glass tubes. There it formed a frozen fog on the inside walls.

Later, the team at NOSAMS would transform the frozen carbon dioxide into chips of graphite, which they would then load into what looks like an enormous, crooked laser cannon. At one end of the cannon, graphite gets vaporized, and the liberated carbon atoms fly down the barrel. By controlling the magnetic field and other conditions inside the cannon, the researchers cause the carbon 14 atoms to veer away from the carbon 12 atoms and other elements. The carbon 14 atoms fly onward on their own until they strike a sensor.

Ultimately, all of this effort will end up in a number: the number of carbon 14 atoms in the red-snapper lens. For Barnett, every one of those atoms counts. They can tell her the exact age of the red snapper when the fish were caught.

That’s because lenses are peculiar organs. Most of our cells keep making new proteins and destroying old ones. Cells in the lens, however, fill up with light-bending proteins and then die, their proteins locked in place for the rest of our life. The layers of cells at the core of the red-snapper lenses have the same carbon 14 levels that they did when the fish were in their eggs.

Using lenses to estimate the ages of animals is still a new undertaking. But it’s already delivered some surprises. In 2016, for example, a team of Danish researchers studied the lenses from Greenland sharks ranging in size from two and a half to 16 feet long. The lenses of the sharks up to seven feet long had high levels of radiocarbon in them. That meant the sharks had hatched no earlier than the 1960s. The bigger sharks all had much lower levels of radiocarbon in their lenses—meaning that they had been born before Castle Bravo. By extrapolating out from these results, the researchers estimated that Greenland sharks have a staggeringly long life span, reaching up to 390 years or perhaps even more.

Barnett has been developing an even more precise clock for her red snapper, taking advantage of the fact that the level of bomb radiocarbon peaked in the Gulf of Mexico in the 1970s and has been falling ever since. By measuring the level of bomb radiocarbon in the center of the snapper lenses, she can determine the year when the fish hatched.

Knowing the age of fish with this kind of precision is powerful. Fishery managers can track the ages of the fish that are caught each year, information that they can then use to make sure their stocks don’t collapse. Barnett wants to study fish in the Gulf of Mexico to see how they were affected by the Deepwater Horizon oil spill of 2010. Their eyes can tell her how old they were when they were hit by that disaster.

When it comes to carbon, we are no different than red snapper or Greenland sharks. We use the carbon in the food we eat to build our body, and the level of bomb radiocarbon inside of us reflects our age. People born in the early 1960s have more radiocarbon in their lenses than people born before that time. People born in the years since then have progressively less.

For forensic scientists who need to determine the age of skeletal remains, lenses aren’t much help. But teeth are. As children develop teeth, they incorporate carbon into the enamel. If people’s teeth have a very low level of radiocarbon, it means that they were born well before Castle Bravo. People born in the early 1960s have high levels of radiocarbon in their molars, which develop early, and lower levels in their wisdom teeth, which grow years later. By matching each tooth in a jaw to the bomb curve, forensic scientists can estimate the age of a skeleton to within one or two years.

Even after childhood, bomb radiocarbon chronicles the history of our body. When we build new cells, we make DNA strands out of the carbon in our food. Scientists have used bomb radiocarbon in people’s DNA to determine the age of their cells. In our brains, most of the cells form around the time we’re born. But many cells in our hearts and other organs are much younger.

We also build other molecules throughout our lives, including fat. In a September 2019 study, Kirsty Spalding of the Karolinska Institute, near Stockholm, used bomb radiocarbon to study why people put on weight. Researchers had long known that our level of fat is the result of how much new fat we add to our body relative to how much we burn. But they didn’t have direct evidence for exactly how that balance influences our weight over the course of our life.

Spalding and her colleagues found 54 people from whom doctors had taken fat biopsies and asked if they could follow up. The fat samples spanned up to 16 years. By measuring the age of the fat in each sample, the researchers could estimate the rate at which each person added and removed fat over their lives.

The reason we put on weight as we get older, the researchers concluded, is that we get worse at removing fat from our bodies. “Before, you could intuitively believe that the rate at which we burn fat decreases as we age,” Spalding says, “but we showed it for the first time scientifically.”

Unexpectedly, though, Spalding discovered that the people who lost weight and kept it off successfully were the ones who burned their fat slowly. “I was quite surprised by that data,” Spalding said. “It adds new and interesting biology to understanding how to help people maintain weight loss.”

C hildren who are just now going through teething pains will have only a little more bomb radiocarbon in their enamel than children born before Castle Bravo did. Over the past six decades, the land and ocean have removed much of what nuclear bombs put into the air. Heather Graven, a climate scientist at Imperial College London, is studying this decline. It helps her predict the future of the planet.

Graven and her colleagues build models of the world to study the climate. As we emit fossil fuels, the extra carbon dioxide traps heat. How much heat we’re facing in centuries to come depends in part on how much carbon dioxide the oceans and land can remove. Graven can use the rise and fall of bomb radiocarbon as a benchmark to test her models.

In a recent study, she and her colleagues unleashed a virtual burst of nuclear-weapons tests. Then they tracked the fate of her simulated bomb radiocarbon to the present day. Much to Graven’s relief, the radiocarbon in the atmosphere quickly rose and then gradually fell. The bomb spike in her virtual world looks much like the one recorded in Joseph Fay’s beech tree.

Graven can keep running her simulation beyond what Fay’s beech and other records tell us about the past. According to her model, the level of radiocarbon in the atmosphere should drop in 2020 to the level before Castle Bravo.

“It’s right around now that we’re crossing over,” Graven told me.

Graven will have to wait for scientists to analyze global measurements of radiocarbon in the air to see whether she’s right. That’s important to find out, because Graven’s model suggests that the bomb spike is falling faster than the oceans and land alone can account for. When the ocean and land draw down bomb radiocarbon, they also release some of it back into the air. That two-way movement of bomb radiocarbon ought to cause its concentration in the atmosphere to level off a little above the pre–Castle Bravo mark. Instead, Graven’s model suggests, it continues to fall. She suspects that the missing factor is us.

We mine coal, drill for oil and gas, and then burn all that fossil fuel to power our cars, cool our houses, power our factories. In 1954, the year that John Clark set off Castle Bravo, humans emitted 6 billion tons of carbon dioxide into the air. In 2018, humans emitted about 37 billion tons. As Willard Libby first discovered, this fossil fuel has no radiocarbon left. By burning it, we are lowering the level of radiocarbon in the atmosphere, like a bartender watering down the top-shelf liquor.

If we keep burning fossil fuels at our accelerating rate, the planet will veer into climate chaos. And once more, radiocarbon will serve as a witness to our self-destructive actions. Unless we swiftly stop burning fossil fuels, we will push carbon 14 down far below the level it was at before the nuclear bombs began exploding.

To Graven, the coming radiocarbon crash is just as significant as the bomb spike has been. “We're transitioning from a bomb signal to a fossil-fuel-dilution signal,” she said.

The author Jonathan Weiner once observed that we should think of burning fossil fuels as a disturbance on par with nuclear-weapon detonations. “It is a slow-motion explosion manufactured by every last man, woman and child on the planet,” he wrote. If we threw up our billions of tons of carbon into the air all at once, it would dwarf Castle Bravo. “A pillar of fire would seem to extend higher into the sky and farther into the future than the eye can see,” Weiner wrote.

Bomb radiocarbon showed us how nuclear weapons threatened the entire world. Today, everyone on Earth still carries that mark. Now our pulse of carbon 14 is turning into an inverted bomb spike, a new signal of the next great threat to human survival.

This article is part of our Life Up Close project, which is supported by the HHMI Department of Science Education.

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These are science’s top 10 erroneous results.

Mistakes from the past demonstrate the reliability of science

By Tom Siegfried

Contributing Correspondent

November 10, 2020 at 6:00 am

Astronomers viewing supernova 1987A, pictured here, thought they saw a signal from a rapidly spinning neutron star too bizarre to comprehend. But the signal turned out to come from a quirk in the electronics of a camera used to aim the telescope.

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To err is human, which is really not a very good excuse.

And to err as a scientist is worse, of course, because depending on science is supposed to be the best way for people to make sure they’re right. But since scientists are human (most of them, anyway), even science is never free from error. In fact, mistakes are fairly common in science, and most scientists tell you they wouldn’t have it any other way. That’s because making mistakes is often the best path to progress. An erroneous experiment may inspire further experiments that not only correct the original error, but also identify new previously unsuspected truths.

Still, sometimes science’s errors can be rather embarrassing. Recently much hype accompanied a scientific report about the possibility of life on Venus. But instant replay review has now raised some serious concerns about that report’s conclusion. Evidence for the gas phosphine, a chemical that supposedly could be created only by life (either microbes or well-trained human chemists), has started to look a little shaky. ( See the story by well-trained Science News reporter Lisa Grossman.)

While the final verdict on phosphine remains to be rendered, it’s a good time to recall some of science’s other famous errors. We’re not talking about fraud here, or just bad ideas that were worth floating but flopped instead, or initial false positives due to statistical randomness. Rather, let’s just list the Top 10 erroneous scientific conclusions that got a lot of attention before ultimately getting refuted. (With one exception, there will be no names, for the purpose here is not to shame.)

10.  A weird form of life

A report in 2010 claimed that a weird form of life incorporates arsenic in place of phosphorus in biological molecules. This one sounded rather suspicious, but the evidence, at first glance, looked pretty good. Not so good at second glance , though. And arsenic-based life never made it into the textbooks.

9. A weird form of water

In the 1960s, Soviet scientists contended that they had produced a new form of water. Ordinary water flushed through narrow tubes became denser and thicker, boiled at higher than normal temperatures and froze at much lower temperatures than usual. It seemed that the water molecules must have been coagulating in some way to produce “polywater.” By the end of the 1960s chemists around the world had begun vigorously pursuing polywater experiments. Soon those experiments showed that polywater’s properties came about from the presence of impurities in ordinary water.

8. Neutrinos, faster than light

Neutrinos are weird little flyweight subatomic particles that zip through space faster than Usain Bolt on PEDs. But not as fast as scientists claimed in 2011, when they timed how long it took neutrinos to fly from the CERN atom smasher near Geneva to a detector in Italy. Initial reports found that the neutrinos arrived 60 nanoseconds sooner than a beam of light would. Faster-than-light neutrinos grabbed some headlines, evoked disbelief from most physicists and induced Einstein to turn over in his grave. But sanity was restored in 2012 , when the research team realized that a loose electrical cable knocked the experiment’s clocks out of sync, explaining the error.

7. Gravitational waves from the early universe

All space is pervaded by microwave radiation, the leftover glow from the Big Bang that kicked the universe into action 13.8 billion years ago. A popular theory explaining details of the early universe —  called inflation — predicts the presence of blips in the microwave radiation caused by primordial gravitational waves from the earliest epochs of the universe.

In 2014, scientists reported finding precisely the signal expected, simultaneously verifying the existence of gravitational waves predicted by Einstein’s general theory of relativity and providing strong evidence favoring inflation. Suspiciously, though, the reported signal was much stronger than expected for most versions of inflation theory. Sure enough, the team’s analysis had not properly accounted for dust in space that skewed the data. Primordial gravitational waves remain undiscovered, though their more recent cousins, produced in cataclysmic events like black hole collisions, have been repeatedly detected in recent years .

6. A one-galaxy universe

In the early 20th century, astronomers vigorously disagreed on the distance from Earth of fuzzy cloudlike blobs shaped something like whirlpools (called spiral nebulae). Most astronomers believed the spiral nebulae resided within the Milky Way galaxy, at the time believed to comprise the entire universe. But a few experts insisted that the spirals were much more distant, themselves entire galaxies like the Milky Way, or “island universes.” Supposed evidence against the island universe idea came from measurements of internal motion in the spirals. It would be impossible to detect such motion if the spirals were actually way far away. But by 1924, Edwin Hubble established with certainty that at least sone of the spiral nebulae were in fact island universes, at vast distances from the Milky Way. Those measurements of internal motion were difficult to make — and they just turned out to be wrong.

5. A supernova’s superfast pulsar

Astronomers rejoiced in 1987 when a supernova appeared in the Large Magellanic Cloud, the closest such stellar explosion to Earth in centuries. Subsequent observations sought a signal from a pulsar, a spinning neutron star that should reside in the middle of the debris from some types of supernova explosions. But the possible pulsar remained hidden until January 1989, when a rapidly repeating radio signal indicated the presence of a superspinner left over from the supernova. It emitted radio beeps nearly 2,000 times a second — much faster than anybody expected (or could explain). But after one night of steady pulsing, the pulsar disappeared. Theorists raced to devise clever theories to explain the bizarre pulsar and what happened to it. Then in early 1990, telescope operators rotated a TV camera (used for guiding the telescope) back into service, and the signal showed up again — around a different supernova remnant. So the supposed signal was actually a quirk in the guide camera’s electronics — not a message from space.

4. A planet orbiting a pulsar

In 1991, astronomers reported the best case yet for the existence of a planet around a star other than the sun. In this case, the “star” was a pulsar, a spinning neutron star about 10,000 light-years from Earth. Variations in the timing of the pulsar’s radio pulses suggested the presence of a companion planet, orbiting its parent pulsar every six months. Soon, though, the astronomers realized that they had used an imprecise value for the pulsar’s position in the sky in such a way that the signal anomaly resulted not from a planet, but from the Earth’s motion around the sun.

3. Age of Earth

In the 1700s, French naturalist Georges-Louis Leclerc, Comte de Buffonestimated an Earth age of about 75,000 years, while acknowledging it might be much older. And geologists of the 19th century believe it to be older still — hundreds of millions of years or more — in order to account for the observation of layer after layer of Earth’s buried history. After 1860, Charles Darwin’s new theory of evolution also implied a very old Earth, to provide time for the diversity of species to evolve. But a supposedly definite ruling against such an old Earth came from a physicist who calculated how long it would take an originally molten planet to cool. He applied an age limit of about 100 million years, and later suggested that the actual age might even be much less than that. His calculations were in error, however — not because he was bad at math, but because he didn’t know about radioactivity.

Radioactive decay of elements in the Earth added a lot of heat into the mix, prolonging the cooling time. Eventually estimates of the Earth’s age based on rates of radioactive decay ( especially in meteorites that formed around the same time as the Earth) provided the correct current age estimate of 4.5 billion years or so.

2. Age of the universe

When astronomers first discovered that the universe was expanding, at the end of the 1920s, it was natural to ask how long it had been expanding. By measuring the current expansion rate and extrapolating backward, they found that the universe must be less than 2 billion years old. Yet radioactivity measurements had already established the Earth to be much older, and it was very doubtful (as in impossibly ridiculous) that the universe could be younger than the Earth. Those early calculations of the universe’s expansion, however, had been based on distance measurements relying on Cepheid variable stars.

Astronomers calculated the Cepheids’ distances based on how rapidly their brightness fluctuated, which in turn depended on their intrinsic brightness. Comparing intrinsic brightness to apparent brightness provided a Cepheid’s distance, just as you can gauge the distance of a lightbulb if you know its wattage (oh yes, and what kind of lightbulb it is). It turned out, though, that just like lightbulbs, there is more than one kind of Cepheid variable , contaminating the expansion rate calculations. Nowadays converging methods give an age of the universe of 13.8 billion years, making the Earth a relative newcomer to the cosmos.

1. Earth in the middle

OK, we’re going to name and blame Aristotle for this one. He wasn’t the first to say that the Earth occupies the center of the universe, but he was the most dogmatic about it, and believed he had established it to be incontrovertibly true — by using logic. He insisted that the Earth must be in the middle because earth (the element) always sought to move toward its “natural place,” the center of the cosmos. Even though Aristotle invented formal logic, he apparently did not notice a certain amount of circularity in his argument. It took a while, but in 1543 Copernicus made a strong case for Aristotle being mistaken. And then in 1610 Galileo’s observation that Venus went through a full set of phases sealed the case for a sun-centered solar system.

Now, it would be nice if there were a lesson in this list of errors that might help scientists do better in the future. But the whole history of science shows that such errors are actually unavoidable. There is a lesson, though, based on what the mistakes on this list have in common: They’re all on a list of errors now known to be errors. Science, unlike certain political philosophies and personality cults, corrects its mistakes. That’s the lesson, and that’s why respecting science is so important to avoiding errors in other realms of life.

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Infographic: The impact of nuclear tests around the world

Since 1945, more than 2,000 nuclear test explosions have been conducted by at least eight nations.

August 29 marks the International Day against Nuclear Tests. The day, declared by the United Nations in 2009, aims to raise awareness of the effects of nuclear weapons testing and achieve a nuclear-weapons-free world.

On July 16, 1945, during World War II, the United States detonated the world’s first nuclear weapon, codenamed Trinity, over the New Mexico desert.

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Less than a month later, the US dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki, killing more than 100,000 people instantly.

Thousands more died from their injuries, radiation sickness and cancer in the years that followed, bringing the toll closer to 200,000, according to the US Department of Energy’s history of the Manhattan Project.

Nuclear warheads per country

Nine countries possessed roughly 12,700 warheads as of early 2022, according to the Federation of American Scientists. Approximately 90 percent are owned by Russia (5,977 warheads) and the US (5,428 warheads).

At its peak in 1986, the two rivals had nearly 65,000 nuclear warheads between them, making the nuclear arms race one of the most threatening events of the Cold War.

While Russia and the US have dismantled thousands of warheads, several countries are thought to be increasing their stockpiles, notably China.

The only country to voluntarily relinquish nuclear weapons is South Africa. In 1989, the government halted its nuclear weapons programme and in 1990 began dismantling its six nuclear weapons. In 1991, South Africa joined the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) as a non-nuclear country.

Which countries have carried out nuclear tests?

According to the Arms Control Association , at least eight countries have carried out a total of 2,056 nuclear tests since 1945.

The US has conducted half of all nuclear tests, with 1,030 tests between 1945 and 1992. In 1954, the US exploded its largest nuclear weapon, a 15 megatonne bomb, on the surface of the Bikini Atoll in the Marshall Islands, the test was codenamed Castle Bravo. The power of the nuclear test was miscalculated by scientists, and it resulted in radiation contamination that impacted inhabitants of the atolls. The nuclear fallout of the explosion is said to have spread over 18,130 square kilometres  (7,000 square miles).

The Soviet Union carried out the second highest number of nuclear tests at 715 tests between 1949 and 1990. The USSR’s first nuclear test was on August 29, 1949. The test, codenamed RDS-1, was conducted at the Semipalatinsk test site in Kazakhstan. According to the CTBTO, the Soviet Union conducted 456 tests at the Semipalatinsk test site, with devastating consequences for the local population such as genetic defects and high cancer rates.

Kazakhstan closed the Semipalatinsk test site on August 29, 1991. Following this move, the UN established August 29 as the International Day against Nuclear Tests in 2009.

France has carried out 210 nuclear tests, while the United Kingdom and China have each carried out 45 tests.

India has carried out three nuclear tests, while Pakistan has carried out two.

North Korea is the most recent nation to carry out a nuclear test. In 2017, its sixth and most powerful bomb was detonated at the Punggye-ri nuclear test site. The underground explosion created a magnitude-6.3 tremor.

The largest nuclear detonations

The largest nuclear explosion occurred in 1961, when the Soviet Union exploded the Tsar Bomba on Novaya Zemlya north of the Arctic Circle. The explosion’s yield was 50 megatonnes, 3,300 times more powerful than the nuclear bomb dropped on Hiroshima.

Other major nuclear explosions by different nations include China’s largest detonation in Lop Nur in 1976, the test had a yield of four megatonnes.

The UK conducted a series of nuclear tests in the South Pacific Ocean between November 1957 and September 1958 as part of Operation Grapple. Grapple Y was the largest of the operation’s nuclear tests, with a yield of three megatonnes.

A survey conducted in 1999 by the British Nuclear Veterans Association found that the impact of the tests on 2,500 veterans who had been present showed skeletal abnormalities and 30 percent of the men had died, mostly in their fifties.

In 1968, France conducted a series of nuclear tests codenamed Canopus at Fangataufa Atoll in the South Pacific Ocean. The test had a yield of 2.6 megatonnes and was 200 times more powerful than the Hiroshima bomb.

Nuclear test sites

Nuclear weapons have been tested all around the world.

On February 13, 1960, France carried out its first nuclear test, codenamed Gerboise Bleue, over the Sahara desert in Algeria – which it was occupying at the time.

Other nuclear test sites include a number in the United States in the states of Nevada, New Mexico, Colorado and Mississippi.

Tests have been carried out in Australia, China, India, Kazakhstan, North Korea, Russia, and Pakistan as well as on French Polynesia, Kiritimati, the Marshall Islands, Prince Edward Island in the Indian Ocean and in the open sea in the eastern Pacific and south Atlantic Ocean.

In 1979, a US Vela satellite detected an atmospheric nuclear explosion over Prince Edward Island in the Indian Ocean. Many believe this was an undeclared joint nuclear test carried out by South Africa and Israel.

What does a nuclear test involve?

Nuclear explosions are either detonated in the atmosphere or underground.

About a quarter of all nuclear tests were detonated in the atmosphere, which spread radioactive materials through the air. To minimise the release of radioactive material, most nuclear tests are underground.

Before a nuclear test is conducted, a suitable test site must be located and prepped. A hole is drilled into the ground in which the nuclear device is placed.

The hole is stemmed with gravel, sand and other materials to prevent radioactive material from escaping. Radiation monitors are activated and aircraft circle the test site to track the capabilities of the device, with weather and fallout patterns being reviewed.

When the device is detonated, energy is released almost instantaneously, producing high temperatures and pressure, which vaporise the nuclear device and the surrounding subterranean rock area.

A cavity forms where the detonation happened and, as the hot gases cool, molten rock puddles at the bottom of the cavity. After a while, the weight of the overburden causes the cavity roof to collapse and a rubble chimney extends to the surface, forming a subsidence crater – a bowl-shaped depression with a diameter of up to 600m (1969 feet) and a depth of up to 60m (197 feet).

After the test is conducted, the site remains guarded –  samples and data are retrieved later.

Impact of different levels of radiation

Nuclear testing has immediate and long-term effects caused by radiation and radioactive fallout. Increased rates of cancer have been associated with nuclear testing, with studies showing that thyroid cancer is linked to radionuclides.

After a nuclear test, large areas of land remain radioactive for decades after the test.

The health impact of different levels of radiation varies from nausea and vomiting to death within days.

Radiation exposure is measured in roentgen equivalent man (rem) – a unit of radiation measurement applied to humans resulting from exposure to one or many types of ionising radiation.

The infographic below shows the impact of radiation on the human body.

A restart of nuclear testing offers little scientific value to the US and would benefit other countries

Scientist-in-Residence and Adjunct Professor, Middlebury

Senior Fellow, James Martin Center for Nonproliferation Studies, Middlebury

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The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

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More than seventy five years ago, on August 6, 1945, a U.S. plane dropped a nuclear bomb on Hiroshima, Japan. This happened only a few short weeks after scientists in the U.S. conducted the world’s first successful nuclear test. The Trinity Test, in New Mexico’s Jornada del Muerto desert, proved that the design of the bomb worked and started the nuclear era .

The U.S. tested nuclear bombs for decades after World War II. But at the end of the Cold War in 1992, the U.S. government imposed a moratorium on U.S. testing . This was strengthened by the Clinton administration’s decision to sign the Comprehensive Nuclear Test Ban Treaty . Although the Senate never ratified the treaty and it never entered into force, all 184 countries that signed the test ban, including the U.S., have followed its rules.

But in recent weeks, the Trump administration and Congress have begun debating whether to restart active testing of nuclear weapons on U.S. soil .

Some conservative Republicans have long expressed concerns over the reliability of aging U.S. warheads and believe that testing is a way to address this problem . Additionally, the U.S., Russia and China are producing novel types of nuclear missiles or other delivery systems and replacing existing nuclear weapons – some of which date to the Cold War – with updated ones. Some politicians in the U.S. are concerned about the reliability of these untested modern weapons as well.

We are two nuclear weapons researchers – a physicist and an arms control expert – and we believe that there is no value, from either the scientific nor diplomatic perspective, to be gained from resuming testing. In fact, all the evidence suggests that such a move would threaten U.S. national security.

Why did the US stop testing?

Since the Trinity Test in July 1945, the U.S. has detonated 215 warheads above ground and 815 underground . These were done to test new weapon designs and also to ensure the reliability of older ones.

When the Cold War ended, the U.S. pledged to stop doing such tests and a group within the United Nations began putting together the CTBT . The goal of the test ban treaty was to hinder new nations from developing nuclear arsenals and limit the capabilities of nations that already had them.

Subcritical testing to maintain the arsenal

After the U.S moratorium went into effect, the U.S. Department of Energy created a massive program called the Stockpile Stewardship Program to maintain the safety and reliability of U.S. nuclear weapons. Instead of crudely blowing up weapons to produce a nuclear explosion, scientists at facilities like U1A in Nevada began conducting what are called subcritical tests .

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In these tests, the plutonium that drives the nuclear chain reactions is replaced by a similar-acting but non-nuclear explosive material such as tungsten or a modified plutonium shell. There is still a big bang, but no nuclear chain reaction.

Rather, these experiments produce data that researchers feed into elaborate supercomputer programs built using the massive amounts of information collected from earlier live tests. Using these subcritical tests and earlier data, scientists can simulate full-scale detonations with incredible accuracy and monitor the current arsenal without blowing up nuclear warheads .

What could be going wrong in the bombs?

All nuclear weapons currently in the U.S. stockpile are two-stage nuclear weapons called hydrogen bombs . Put simply, hydrogen bombs work by using a smaller nuclear bomb – akin to the bomb dropped on Nagasaki – to detonate a second, much more powerful bomb.

Nearly all the components of a nuclear weapon can be replaced and updated except for one piece – the explosive plutonium core known as the pit . These pits are what trigger the second, larger explosion.

The weapons in the U.S. arsenal are, on average, about 25 years old . The main concern of people pushing to resume testing is that the plutonium pits may have deteriorated from their own radiation in the time since they were made and will not properly trigger the second fusion stage of the explosion.

Since most of the previous tests were done on much younger bombs with newer plutonium pits, supporters of testing claim that the subcritical tests cannot accurately test this part of the process .

The deterioration of the plutonium pit is a valid concern. To study this, researchers at Lawrence Livermore National Laboratory used a far more radioactive type of plutonium and artificially aged the metal to simulate the effects of what would be equivalent to 150 years of radiation on a normal plutonium pit. They found that the aged plutonium pits “will retain their size, shape, and strength despite increasing damage from self-irradiation,” and concluded that “the pits will function as designed up to 150 years after they have been manufactured. ”

This isn’t to say that scientists can stop worrying about the aging of U.S. nuclear weapons. It’s important to continue “to assess and, if necessary mitigate threats to primary performance caused by plutonium aging”, as the JASON group – a group of elite scientists that advises the U.S. government – says.

However, these scientists do not suggest that it is necessary to conduct live nuclear tests . Decades of experimental studies by nuclear weapons laboratories have led experts to believe that the U.S. can maintain the nuclear arsenal without testing. And in fact, as the former director of Los Alamos National Labs, Dr. Sigfried Hecker said recently, many believe that by resuming testing, “ we would lose more than we gain .”

Little to gain, much to lose

Nuclear weapons are intricately tied to the world of geopolitics. So if there isn’t a scientific need to resume testing, is there some political or economic reason?

The U.S. has already spent tens of billions of dollars on the infrastructure needed to conduct subcritical tests. Additionally, a new, billion-dollar facility is currently being built in Nevada that will provide even finer detail to the data from subcritical test explosions. Once subcritical test facilities are up and running, it is relatively inexpensive to run experiments. Nuclear testing won’t save the U.S. money.

So is it politics?

Currently, nuclear powers around the world are all improving the missiles that carry nuclear warheads, but not yet the warheads themselves.

With little evidence, the Trump administration has sought to sow suspicion that Russia and China may be secretly conducting very low-yield nuclear tests, implying that the countries are trying to build better nuclear warheads . In response, movement towards testing in the U.S. has already begun.

The Senate Armed Services Committee recently approved an amendment to spend US$10 million to cut the time it would take to conduct a test if the president ordered one . Some officials seem to believe that a resumption of U.S. testing – or the threat of it – could give Washington an upper hand in future arms control negotiations .

But we believe the opposite to be true. Even though the Comprehensive Test Ban Treaty has not entered into force, nearly every nuclear power on earth has more or less followed its rules. But if the U.S. were to resume nuclear testing, it would be a green light for all other nations to start their own testing.

The U.S. already has the ability to perform subcritical tests and data from over 1,000 test detonations that scientists can use to modernize, improve and maintain the current arsenal. No other country, aside from Russia, has as robust a foundation. If the ban were broken, it would give other countries like Iran, India, Pakistan and China a chance to gather huge amounts of information and improve their weapons while the U.S. would gain next to nothing.

When it comes to the U.S nuclear testing ban, our view is, if it ain’t broke don’t fix it.

This story was updated on August 3, 2020 to refer to the 75th anniversary of the Hiroshima bombing.

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Introduction: Nuclear testing in the 21st century—legacies, tensions, and risks

By François Diaz-Maurin | March 7, 2024

Despite an international treaty banning all nuclear detonations, the issue of nuclear weapons testing is taking center stage once again. Last November, Russia officially withdrew its ratification of the Comprehensive Nuclear Test Ban Treaty. Earlier in 2023, Russian President Vladimir Putin stated that Moscow will not resume nuclear testing “unless the United States does so”—a possibility experts view as highly unlikely under the current US administration.

But despite officials—in Russia and elsewhere—saying that they will not resume nuclear testing, some evidence could suggest otherwise.

Satellite imagery has shown increased construction activities happening since 2021 in recent years at nuclear testing sites in the United States, Russia, and China—the world’s three largest nuclear powers.

Experts believe that Russia and China are currently expanding underground tunnels at their nuclear test sites of Novaya Zemlya and Lop Nur, respectively. In the United States, the National Security Administration is also expanding the Nevada Test Site, officially to improve the diagnostic capabilities for the management and performance of the US nuclear stockpile, without the need to conduct any more underground nuclear explosive tests. But, at the same time, the United States maintains a policy of readiness, by which the country is prepared to conduct a nuclear test within six months should one of its adversaries conduct one.

In this game of who-moves-first, other nuclear-armed countries are watching closely.

North Korea is ready to conduct another underground nuclear test—its seventh—and is only waiting a political decision by Leader Kim Jong-un to do so, which may come at any time. North Korea is the only country to have tested nuclear weapons in the 21 st century. Also watching are India and Pakistan—countries whose latest tests were conducted in 1998 and who haven’t signed the test ban treaty. They may seek any opportunity to test another nuclear device.

To help make sense of how recent developments are putting to test the resolve of nuclear powers to continue with observing their testing moratoria, policy experts and scientists provide here a comprehensive set of articles about the current challenges of nuclear weapons testing—from the enduring legacy of past nuclear tests to the new tensions over suspected testing activities.

In “ The logic for US ratification of the Comprehensive Nuclear Test Ban Treaty ,” Steven Pifer, the former US Ambassador to Ukraine, explains why it would be in the interests of the United States to ratify the nuclear test ban treaty.

Nuclear expert Pavel Podvig argues in his piece, “ Preserving the nuclear test ban after Russia revoked its CTBT ratification ,” that transparency in the US nuclear experiments will be critical to preserving the moratorium on nuclear explosions and could encourage Russia and China to be more transparent about their activities too.

In her piece, “ To do or not to do: Pyongyang’s seventh nuclear test calculations ,” nuclear policy expert Rachel Minyoung Lee asks the Shakespearean question of why North Korea may—or may not—conduct its next underground nuclear test.

In a more technical article, Earth scientists Sulgiye Park and Rodney C. Ewing review the long-term environmental impacts of past underground nuclear tests . In a similarly technical piece, physicists Julien de Troullioud de Lanversin and Christopher Fichtlscherer explain the fuzzy line between nuclear tests and nuclear experiments —and how arms control tools can help reduce tensions around the various interpretations of what “zero yield” means.

In his piece, Walter Pincus, former Washington Post reporter and author of the book Blown To Hell about US nuclear testing, reminds Bulletin readers what a single nuclear test explosion in the atmosphere can do —something new generations cannot grasp easily, given that the last known atmospheric test was conducted in October 1980 (by China).

Finally, in their latest column of the Nuclear Notebook, “ Russian nuclear weapons, 2024 ,” Hans M. Kristensen, Matt Korda, Eliana Johns, and Mackenzie Knight of the Federation of American Scientists’ Nuclear Information Project discuss recent activities at the Novaya Zemlya test site and Russia’s withdrawal of its ratification from the nuclear test ban treaty.

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Keywords: CTBT , China , Comprehensive Nuclear Test Ban Treaty , Nevada Test Site , North Korea , Russia , arms control , nuclear testing , nuclear weapon tests Topics: Nuclear Weapons

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François Diaz-Maurin

François Diaz-Maurin is the associate editor for nuclear affairs at the Bulletin of the Atomic Scientists . Previously, Diaz-Maurin was a... Read More

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14 Experiments Gone Wrong

By stacy conradt | mar 23, 2021.

From psychological studies that would never pass ethical muster in the present day to disastrous new product launches, here are some experiments gone horrifically wrong, adapted from an episode of The List Show on YouTube.

1. Winthrop Kellogg's Ape Experiment

In the early 1930s, comparative psychologist Winthrop Kellogg and his wife welcomed a healthy baby boy they named Donald. The psychologist had grown interested in those stories of children who were raised feral—but he didn’t send Donald to be raised by wolves. He did the opposite: He managed to get his hands on a similar-aged baby chimp named Gua and raised her alongside Donald.

Gua initially did better than Donald in tests that included things like memory, scribbling, strength, dexterity, reflexes, problem-solving, climbing, language comprehension, and more. But she eventually plateaued, and it became evident that no amount of equal treatment was going to make her behave more like a human (for example, she was never going to be able to speak English).

But when the Kelloggs ended the experiment, they did so abruptly and without much explanation, which is contrary to the meticulous records they otherwise took throughout the course of the study. While Gua wasn’t showing any signs of picking up English, Donald had started to imitate the vocalizations of his sister from another species—so it’s not hard to speculate why the Kelloggs called it quits.

2. The Stanford Prison Experiment

You may have heard about the Stanford Prison Experiment, a social psychology study gone awry in 1971. The point of the experiment, which was funded by the U.S. Office of Naval Research, was to measure the effect of role-playing and social expectations. Lead researcher Philip Zimbardo had predicted that situations and circumstances dictate how a person acts, not their personalities.

To start, 24 young men were assigned the roles of prison guard or prison inmate, with some held back as alternates. Each was paid $15 per day for his participation in the study, which was supposed to last two weeks. The prisoners were “arrested,” taken to a fake prison in the basement of a school building, then made to wear a dress-like prison uniform with chains around their right ankle.

By the second day, the faux prisoners had revolted. Over the next few days, some of the prisoners were so traumatized that they were pulled out. The experiment was disbanded on day six, after an outside observer witnessed the upsetting events taking place and sounded the alarm.

Many modern-day researchers don’t believe the experiment can be replicated because it doesn’t meet today’s research ethics standards—namely, informed consent. After all, it’s hard to give fully informed consent when there’s no way to predict how events could unfold. Beyond that, some psychologists doubt the core findings of the experiment and claim that the cruelty didn’t emerge organically, but was instead influenced by Zimbardo nudging the experiment in that direction. Zimbardo, however, has defended his results and stated that these criticisms are misrepresenting his study and the experiences of the people in it.

3. Franz Reichelt's Aviator Suit

If there's anything to be said for Franz Reichelt, it's that he had supreme confidence in his own invention. In the early 1900s, Reichelt crafted a parachute from 320 square feet of fabric, all of which folded up into a wearable aviator suit . He had conducted several parachute tests using dummies, which all failed. He pinned the blame on the buildings, saying that they simply weren’t tall enough.

In 1912, Reichelt planned to test his latest version by flinging a dummy from the Eiffel Tower. But when he arrived at the famous landmark, the inventor surprised the waiting crowd by strapping on the parachute suit himself and taking the leap. The parachute didn’t open, however, and Reichelt became a victim of his own invention. (An autopsy reportedly determined that he died of a heart attack on the way down.)

4. McDonald's Bubblegum-Flavored Broccoli

In 2014, McDonald's concluded that they needed to offer more nutritious options for children—which led one mad scientist in Ronald’s test kitchen to come up with bubble gum-flavored broccoli. Luckily for all of us, this horrifying experiment never made it to a Happy Meal near you.

5. William Perkin's Mauve-lous Mistake

In 1856, chemist William Perkin   was experimenting with ways to manufacture a synthetic version of quinine, a tonic water ingredient that also happens to treat malaria. At the time, dyes were only made from things like plant material and insects—but when Perkin was mixing up his latest quinine concoction, he accidentally produced an oily sludge that left a lovely shade of light purple residue. He had unwittingly discovered a way to produce mauve. The color was a smash hit, especially after Queen Victoria donned it for her daughter’s 1858 wedding. 

6. The Michelson-Morley Experiment

Another happy failure is the Michelson-Morley Experiment. The experiment was supposed to detect ether , a substance that carried light waves, according to some scientists. The working theory at the time, in the late 1800s, was that ether was motionless, so the motion of Earth through space would alter the speed of light depending on what direction you were facing.

This was popularly known as “ether wind.” To test the ether wind theory, scientist Albert Michelson invented a device that could theoretically measure changes to the speed of light, thus detecting the supposed ether wind. The device was perfectly accurate, but it didn’t detect any changes in the speed of light. What Michelson and his collaborator Edward Morley discovered—or rather, didn’t discover—eventually led to Einstein’s theory of special relativity, and the realization that the speed of light is a universal constant, and there is no absolute space or absolute time.

7. The Cleveland Indians' 10-Cent Beer Night

In 1974, the Cleveland Indians tinkered with a new promotion to increase game attendance—giving fans the opportunity to purchase an unlimited amount of beer for 10 cents a cup , which wasn't the best idea. The game against the Texas Rangers was an eventful one: memorable events of the evening included a woman running into the Indians’ on-deck circle and flashing the umpire; a naked fan running onto the field and sliding into second base; and a father and son who ran onto the outfield and mooned the bleacher section.

Things took a violent turn when fans launched fireworks into the Rangers’ dugout, and the whole thing eventually turned into an all-out riot, fans against players on both teams. Players were hit with folding chairs, there were numerous fist fights, and some players were injured when they were pelted with rocks. After that, the Cleveland Indians kept 10 cent beer nights, but limited the promotion to two drinks per person.

8. Stubbins Ffirth's Yellow Fever Experiment

Stubbins Ffirth was a medical student who believed that yellow fever wasn’t contagious. To prove it, he tried some awful experiments on himself at the turn of the 19th century.

Ffirth cooked vomit from yellow fever patients on his stove and breathed in the vapors. He dropped the vomit into his eye, into an incision he had made in his left arm, and put drops of a patient’s blood serum into his left leg. Eventually, he was basically drinking shots of black vomit—straight. (He described the taste as “Very slightly acid.”)

How did he Ffirth manage to ingest all of this without falling ill? Well, we now know that Yellow Fever is spread by mosquitoes. So maybe Ffirth was vindicated? Is this just a disgusting experiment gone right ?

Not exactly. We also know now that yellow fever can be spread from human to human through direct bloodstream contact, and Ffirth was deliberately introducing samples to his bloodstream. So how’d he avoid contracting the virus? It’s been proposed that he may have had an immunity from an unrecorded bout of yellow fever earlier in life. Or maybe he just got extremely lucky and the samples he used were virus-free. Either way, if you’re chugging vomit and cutting open your arm to introduce a potentially lethal virus, it’s fair to say that something has gone wrong.

9. Biosphere 2

In the early ‘90s, eight scientists sealed themselves into a 3.14-acre structure in Arizona. The highly-publicized, $200-million experiment was known as Biosphere 2, and according to one of the scientists involved, its goals included “education, eco-technology development and learning how well our eco-laboratory worked.” But the scientists ran into a number of problems that required outside interference in order to continue the experiment, including a lack of sunlight that affected crops, a cockroach infestation, an injured crew member who had to temporarily leave for treatment, and insufficient oxygen.

In recent years, however, the success of Biosphere 2 has been re-evaluated , with some scientists believing that the base message—that humans can live in harmony with our biosphere—was a win in and of itself. And even if the vast investment was viewed as a mistake, the underlying idea remains solid: Similar experiments have been recently conducted to see if we can sustain human life on Mars.

10. The New Ball

Although basketball was originally played with soccer balls, a leather ball has been used since Spalding began manufacturing sport-specific balls in 1894. The basketball has been tweaked here and there over the years, but the modifications apparently went too far when the NBA experimented with a microfiber ball in 2006. “The New Ball,” as it was commonly known, was cheaper to make and was supposed to have the feel of a broken-in basketball right from the start.

Sounds good in theory, but players absolutely hated it. Shaquille O’Neal, LeBron James, and Dirk Nowitzki complained about the ball to the press. One issue was that the ball apparently became much more slippery than a traditional leather ball when it was wet, which happened frequently when sweaty basketball players were constantly handling it. Some players even reported that their hands were getting cut due to the increased friction of the microfiber surface.

Dallas Mavericks owner Mark Cuban also commissioned a study from the physics department at the University of Texas at Austin, which found that the ball bounced 5 to 8 percent lower than a traditional leather ball and bounced up to 30 percent more erratically. Feeling deflated, the NBA officially announced they were pulling the ball from play on December 11, 2006—less than three months after its debut in a game.

11. Henry A. Murray's Psychological Experiments

It’s probably safe to say that an experiment falls into the “gone wrong” category when it may have been responsible for producing the Unabomber. As an undergrad at Harvard in the late 1950s and early '60s, Ted Kaczynski participated in a three-year-long study run by Henry A. Murray that explored the effects of stress on the human psyche. After being asked to submit an essay about their worldview and personal philosophies, Kaczynski and 21 other students were interrogated under bright lights, wired to electrodes, and completely torn down for their beliefs. The techniques were intended to “break” enemy agents during the Cold War—and the students were never completely informed about the nature of the study. In short, the man who would eventually kill three people and injure over 20 more with his homemade bombs was subjected to repeated psychological torture.

Kaczynski later described this as the worst experience of his life; still, we can’t assume the study was solely responsible for sending him down the destructive and murderous path he eventually followed. But at the very least, the study is now considered highly unethical and likely wouldn’t pass current ethics standards for research.

12. Wilhelm Reich's Cloudbusters

Psychoanalyst Wilhelm Reich managed to draw a straight line from human orgasms to the weather to alien invasion. Influenced by Sigmund Freud ’s work on the human libido, Reich extended the concept to propose a kind of widespread energy he called orgone. To give you an idea of how scientifically sound Reich’s concept was, orgone has been compared to the Force in Star Wars . This energy was supposedly responsible for everything from the weather to why the sky is blue. Reich believed orgasms were a discharge of orgone, and that through the manipulation of this energy you could treat neuroses and even cancer.

As bizarre as this all sounds, Reich went even further in the late 1950s, when he became convinced that aliens were spraying the earth with a specific type of radiation to prevent us from using this powerful energy. In order to save the world, he and his son built Cloudbusters, a row of tubes attached to hoses immersed in water and aimed at the sky. The water, they believed, would absorb the radiation.

Did the experiment work? We don’t know for sure, but the FDA didn’t think so. They ordered Reich's various machines and apparatus destroyed, and had him jailed for trying to smuggle them out of state.

13. Duncan MacDougall's Soul Experiments

In 1901, Duncan MacDougall conducted experiments on extremely recently deceased people—and dogs—to see if their body weight changed immediately after death. A decrease in weight, he theorized, would be indicative of a physical soul leaving the body. To test this theory, he weighed six people before and after their deaths, and concluded that there was a weight difference anywhere from half to one and a half ounces (somewhere between one and three compact discs). He repeated the experiment on dogs and found no difference—and therefore, by MacDougall’s reasoning, dogs have no souls.

Other scientists have been critical of this experiment from day one, citing issues like small sample size and imprecise methods of measurement.

14. New Coke

April 23, 1985, was a day that will live in marketing infamy. And that’s how Coke describes the failed experiment that was New Coke . On that day, the Coca-Cola Company debuted a new version of their popular soft drink made from a new and supposedly improved formula. It was the first major change to the product in nearly a century, and it was one that was supported by overwhelmingly positive reviews in taste tests and focus groups.

But once New Coke actually hit the shelves, fans were absolutely outraged. While the taste tests accounted for the actual flavor of the new formula, it couldn’t account for the emotional ties consumers had to the brand history. Fans started hoarding “old” Coke, and complaints poured in to the tune of 1500 calls a day. CEO Roberto Goizueta even received a letter addressed to “Chief Dodo, The Coca-Cola Company.”

The message was received loud and clear. Coke announced the return of Old Coke in July, dubbing it Coca-Cola Classic—and they never experimented with the formula again. Or if they did, they kept it to themselves, and we’re none the wiser.

7 Creepiest Science Experiments of All Time That Will Give You Nightmares

Scientists often run into doing crazy things in the quest of discovering something important. but some of these experiments aren’t just worthless but are unbelievably creepy..

Kashyap Vyas

Experiments in the Revival of Organisms

Techfilm Studio/Wikimedia Commons  

Science is a beautiful gift to humanity. It can tell us what is true over mere assumptions by validating the theories with practical experiments. The scientific experiments have often led to important discoveries that eventually helped the mankind to live a better life. Sometimes though, scientists in their quest for knowledge end up conducting experiments that are not only unethical but equally disturbing. The world has witnessed many of such spine-chilling and weird experiments that went badly wrong and even cost lives.

Here’s a list of 7 creepiest science experiments conducted ever that’ll surely give you nightmares:

You might have heard about the inhumane experiments done by Nazis during World War II. But they were not alone.

The Imperial Japanese Army’s Unit 731 carried out atrocities in the name of scientific experiments, some details of which are still left to be uncovered. It was until 1984 that Japan acknowledged about conducting cruel experiments on humans to prepare for germ warfare. Setup in 1938, the objective of Unit 731 was to develop biological weapons and was supported by Japanese universities and medical schools that supplied doctors and research staff to carry out such vile experiments. The unit used thousands of Chinese prisoners and Asian civilians as guinea pigs to develop killer diseases. The experiments included infecting wartime prisoners with cholera, anthrax, plague and other pathogens. Horrific still, some of the experiments involved vivisection without anesthesia and pressure chambers to identify how much a human can take before bursting. What’s creepier is that post-war American administration provided safe passage to some of those involved with Unit 731 in exchange of findings of their experiments.

Tuskegee Syphilis Experiment

The Tuskegee Study of Untreated Syphilis in the Negro Male is infamous because of the tragedy it caused to people suffering from the disease in the name of free treatment. Between 1932 and 1972, 600 men were originally enrolled for the project, consisting of 399 with latent Syphilis and 201 as control group. Monitored by Doctors of U.S. Public Health Service, these men were given only placebos such as aspirin and mineral supplements, rather than treating with penicillin which was the recommended treatment at that time. The purpose of the study was to understand the effect and spread of the disease on human body. Because of the unethical considerations by scientists, 28 participants perished from Syphilis , 100 died because of related complications and more than 40 spouses were diagnosed with the disease, passing Syphilis to 19 children at birth. President Clinton is 1997 issued his apology to the survivors and families of the victims of the study, stating “The United States government did something that was wrong—deeply, profoundly, morally wrong… It is not only in remembering that shameful past that we can make amends and repair our nation, but it is in remembering that past that we can build a better present and a better future.”

Two Headed Dogs

Vladimir Demikhov was a successful surgeon and his studies have helped medical science to advance especially in the field of organ transplant and coronary surgery. Demikhov was the first person to perform a successful coronary artery bypass operation on a warm-blooded creature. But, behind his successful operations, there are few of his experiments that can make you feel uncomfortable. His famous two-headed dog experiment is one of them. He stitched the head, shoulders and front legs of a puppy onto the neck of a German shepherd. Although the surgery was a success as both dogs could move around independent of each other, they didn’t survive very long due to tissue rejection. Demikhov created 20 such two-headed dogs, but the highest one survived only for a month. While the experiment may sound cruel, it indeed helped in pioneering organ transplants in humans.

Testicle Transplants

In one of the most disturbing experiments, Leo Stanley, the physician in charge at San Quentin Prison in California surgically transplanted the testicles of executed criminals into living inmates. Stanley felt that males who committed crimes share a common characteristic – low testosterone levels and raising it would reduce the crime rates. More than 600 inmates became the victim of Stanley’s crazy theory, and when there was a shortage of human testicles, he went on to inject liquefied animal testicles into the prisoners. Stanley claimed that the experiment was a success by citing a Caucasian prisoner who felt “energetic” after transplanting the testicle from an executed African-American convict.

The Stanford Prison Experiment

In 1971, a group of researchers at Stanford University conducted an experiment to investigate the causes of conflict between prisoners and guards. 24 students were assigned the roles of prisoners and guards randomly and were put into a prison-like environment. Meant to last for two weeks, the study was abruptly ended after only six days, as it became difficult to control and maintain order. Despite being told not to use any form of violence, one in every three guards showed their tendency to abuse. Surprisingly, many of the prisoners accepted the abuses and led two of them to suffer emotional trauma. The study showed that how power of situations can influence individual’s behavior.

Zombie Dogs

Known as Experiments in the Revival of Organisms , Russian scientists Dr. Sergei Brukhoneko and Boris Levinskovsky released a video of dog heads that were kept alive by an artificial blood circulation system. Using a special heart-lung apparatus called the autojektor, the scientists showed dog heads responding to sound by wiggling their ears, blinking eyes and even licking their mouths. The experiment was repeated again by American scientists in 2005 by flushing all the blood from the dog and replacing it with oxygen and sugar-filled saline. After three hours, a blood transfusion and an electric shock the dogs were back from dead.

MKUltra is one of the most famous projects conducted by CIA to develop mind-control techniques that can be used against enemies during war. Lasted for more than a decade from 1950 to 1970, the project’s main goal was to remain ahead in the mind-control technology. But the scope widened eventually resulting into illegal drug testing on thousands of Americans. Using drugs like LSD and other chemicals along with other forms of psychological torture, the agency tried to alter brain functions and manipulate mental states of the people. The documentation related to the project was ordered to be destroyed completely, but in 1977 the Freedom of Information Act released more than 20,000 pages on the program.

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The experiment involved 192 high-powered laser beams being fired at a capsule containing the elements deuterium and tritium, heating it to a temperature of more than three million degrees centigrade - thus briefly simulating the conditions of a star.

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US scientists have carried out the first ever nuclear fusion experiment to achieve a net energy gain, paving the way for a "clean energy source that could revolutionise the world".

During a landmark news briefing at the Lawrence Livermore National Laboratory in California, officials revealed the successful fusion experiment had taken place last week.

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How was the experiment carried out?

Dr Marvin Adams said it had been carried out "hundreds of times before", but had never successfully produced more energy than was consumed.

"For the first time, they designed this experiment so that the fusion fuel stayed hot enough, dense enough, and round enough for long enough that it ignited, and it produced more energy than the lasers had deposited," he said.

"About two mega joules in, about three mega joules out - a gain of 1.5, the energy production took less time than it takes light to travel one inch."

It was, as he quipped, "kind of fast".

While the target was smaller than a pea, the lasers - part of the so-called NIF system - are powerful enough to deliver more energy than the whole power grid sustaining all of the US.

Chief engineer Jean-Michel Di Nicola said it was "the size of three football fields and delivers energy in excess of two million joules with a peak power of 500 trillion watts".

"For a very short amount of time, a few billionths of a second, it exceeds the entire US power grid," he said.

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Dr Kim Budil, director of the Lawrence Livermore National Laboratory, admitted it would take "probably decades".

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A significant scientific milestone - but lasers require huge power

Science and technology editor

As Dr Marv Adams was holding up the cylindrical target containing the "peppercorn-sized" pellet of fusion fuel, he confirmed they had achieved "ignition" of a fusion reaction.

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That's the evidence of the "energy gain" that this announcement is all about.

That's the significant scientific milestone: proving a fusion reaction itself can generate more energy than you put into in.

But they had to use 300MJ of electricity to power up their lasers.

So from an energy production point of view, they're still having to put in 99% more power into the machine as a whole as they are getting out.

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"While this is not yet an economically viable power plant, the path for the future is much clearer," he added.

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Jeremy Chittenden, professor of plasma physics at Imperial College London, said scientists "will need to find a way to reproduce the same effect much more frequently and much more cheaply".

If they do, it would be a huge shot in the arm for the world's push towards renewables.

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Harris Chooses Walz

A guide to the career, politics and sudden stardom of gov. tim walz of minnesota, now vice president kamala harris’s running mate..

Hosted by Michael Barbaro

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Earlier this summer, few Democrats could have identified Gov. Tim Walz of Minnesota.

But, in a matter of weeks, Mr. Walz has garnered an enthusiastic following in his party, particularly among the liberals who cheer on his progressive policies. On Tuesday, Vice President Kamala Harris named him as her running mate. Ernesto Londoño, who reports for The Times from Minnesota, walks us through Mr. Walz’s career, politics and sudden stardom.

On today’s episode

Ernesto Londoño , a reporter for The Times based in Minnesota, covering news in the Midwest.

Background reading

Who is Tim Walz , Kamala Harris’s running mate?

Mr. Walz has faced criticism for his response to the George Floyd protests.

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The Daily is made by Rachel Quester, Lynsea Garrison, Clare Toeniskoetter, Paige Cowett, Michael Simon Johnson, Brad Fisher, Chris Wood, Jessica Cheung, Stella Tan, Alexandra Leigh Young, Lisa Chow, Eric Krupke, Marc Georges, Luke Vander Ploeg, M.J. Davis Lin, Dan Powell, Sydney Harper, Michael Benoist, Liz O. Baylen, Asthaa Chaturvedi, Rachelle Bonja, Diana Nguyen, Marion Lozano, Corey Schreppel, Rob Szypko, Elisheba Ittoop, Mooj Zadie, Patricia Willens, Rowan Niemisto, Jody Becker, Rikki Novetsky, Nina Feldman, Will Reid, Carlos Prieto, Ben Calhoun, Susan Lee, Lexie Diao, Mary Wilson, Alex Stern, Sophia Lanman, Shannon Lin, Diane Wong, Devon Taylor, Alyssa Moxley, Olivia Natt, Daniel Ramirez and Brendan Klinkenberg.

Our theme music is by Jim Brunberg and Ben Landsverk of Wonderly. Special thanks to Sam Dolnick, Paula Szuchman, Lisa Tobin, Larissa Anderson, Julia Simon, Sofia Milan, Mahima Chablani, Elizabeth Davis-Moorer, Jeffrey Miranda, Maddy Masiello, Isabella Anderson, Nina Lassam and Nick Pitman.

An earlier version of this episode misstated the subject that Walz’s wife taught. She taught English, not Social Studies.

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Ernesto Londoño is a Times reporter based in Minnesota, covering news in the Midwest and drug use and counternarcotics policy. More about Ernesto Londoño

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