Physicists can help combat the global threat of nuclear weapons, say experts at nuclear physics meeting

Physicists can help combat the global threat of nuclear weapons, say experts at nuclear physics meeting

Plenary speakers at the American Physical Society Meeting on Nuclear Physics discussed the past, present, and future of nuclear weapons.

By Sophia Chen | November 10, 2022

Credit: US Navy Image/Released (Flickr)

In a US test in September 2019, an unarmed ballistic missile called the Trident II D5 was launched from the submarine USS Nebraska off the coast of San Diego.

Alan Roebuck tells one story often. Addressing a virtual audience via Zoom, he repeated it — apparently a success story for politicians listening to scientists — at the fall 2022 meeting of the APS Department of Nuclear Physics.

As the story goes, Roebuck was part of a group of American and Soviet scientists in the 1980s who predicted the consequences of nuclear war using scientific models. The work introduced the public to the concept of nuclear winter. The models predicted that if nations used nuclear weapons again in war, the weapons would not only directly kill millions, but also cause firestorms, the smoke of which would block out sunlight. The resulting climate change will lead to starvation and death worldwide.

Politicians have responded to these realistic expectations, as well as to broader geopolitical shifts. “The arms race is over,” said Roebuck, now a climate scientist at Rutgers University. President Ronald Reagan and Soviet leader Mikhail Gorbachev cited the research as driving this shift. The number of nuclear weapons peaked in 1986, with about 65,000 worldwide. In 2022, 9 countries have 12,720, according to the Nagasaki University Research Center on Nuclear Abolition.

But a disturbing new chapter has begun. Since Russia invaded Ukraine in February 2022, President Vladimir Putin has made veiled statements – for example, that Russia has a “more modern [weapons] of weapons possessed by NATO countries” – which the US government has interpreted as threats to proliferation of nuclear weapons.

Physicists have played an important role in technology development and policymaking related to nuclear weapons, Roebuck, along with three other speakers, expressed during the meeting’s plenary sessions on the nuclear threat and mitigation. Roebuck encouraged meeting attendees to join the Alliance of Physicists for Nuclear Threat Reduction. This group, formed in 2020 with a grant through the APS Innovation Fund, advocates for government policies that reduce nuclear threats.

And nuclear physics research can help advance nonproliferation, as Bethany Goldblum of Lawrence Berkeley National Laboratory discussed in her talk. For example, some researchers are investigating the use of antineutrinos to monitor nuclear material. When radioactive materials such as uranium undergo fission, they release antineutrinos, which can indicate how much material is inside the reactor. If a bad actor removes this substance from a nuclear reactor, an antineutrino detector can identify it.

Roebuck explained that the world still faces serious nuclear dangers. He said the stocks are so great that if a Hiroshima-sized bomb had fallen every two hours since the end of World War II until today, the global arsenal would not be exhausted today.

Nuclear security expert Steve Vetter of the University of Maryland, who co-founded the Alliance of Physicists, provided an overview of the state of the world’s nuclear weapons. Focus mainly on the United States and Russia, which together control more than 90 percent of the world’s stockpile. Both countries have weapons for three different types of deployment – intercontinental ballistic missiles (ICBMs), which are launched via missiles, some of which can reach anywhere on the planet; submarine-launched ballistic missiles, which can launch nuclear weapons of similar range from underwater; and bombers, or aircraft that can carry and deploy nuclear weapons. Russia’s strategy relies on more ICBMs, while the US relies on more submarine-based missiles. Vitter said both countries have about 1,000 nuclear weapons that can be launched within minutes.

Vetter also discussed developments in the field of nuclear weapons. The US government plans to spend $1.3 trillion to replace and modernize its arsenal starting in 2030. “Even by the standards of the US Department of Defense, this is a lot of money,” Vetter said.

Russia has also invested in new nuclear weapons technology. In 2018, Putin announced a new ICBM called the Sarmat with a range of 18,000 km. Vetter said the Sarmat missile “can be launched to attack the United States from the Antarctic to avoid American missile defenses.”

Russia is also developing a missile called Burevestnik that not only carries a nuclear weapon, but is nuclear-powered. “Just saying the phrase ‘flying nuclear reactor’ probably suggests why that’s not the best idea,” Vetter said of the system, which cannot carry radiation protection. In 2019, the Russian Nuclear Energy Agency reported a radiological accident that some experts believe was caused by testing a prototype of this missile. Seven people were killed.

Roebuck made contemporary versions of his nuclear winter models. Working with modelers of climate, oceans and crops, Roebuck’s team predicted the consequences of a nuclear war involving the United States, NATO and Russia, as well as a war between India and Pakistan, two countries with smaller nuclear capabilities.

From a scientific point of view, these models have a unique limitation: there is not a lot of data to verify their accuracy. In addition to using information from the Hiroshima and Nagasaki nuclear explosions in World War II, researchers are also looking at climate events with potential isotopes — for example, bushfires in Australia and Canada in the past decade.

In their study published in nature foodsRoebuck and his colleagues found that a war between India and Pakistan could kill more than two billion people, and a war between the United States and NATO against Russia could kill more than 5 billion. They also found that about 20 times more people die of starvation than people die directly from nuclear war. (Some researchers who have formulated possible scenarios predicted much less severe global impacts.)

“So what do you do with this information?” asked Roebuck. The most natural reaction is to try to forget about it. As Mark Twain said, “Denial is not just a river in Egypt.”

But he also sought to give listeners a sense of agency. “My reaction is to try to do something about it,” Roebuck said. In 2017, the United Nations passed a treaty to ban nuclear weapons, and 68 countries have ratified it, although the United States and Russia have not. “The story of nuclear weapons will end, and it is up to us what that end will be,” Beatrice Fein, whose organization, the International Campaign to Abolish Nuclear Weapons, won the Nobel Peace Prize in 2017, was quoted as saying.

Sophia Chen is a writer based in Columbus, Ohio.

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