Published 1 October 2026 by LINO News
“The Half-Life of Civilization Is 34 Years.” Three Nobel Laureates Just Did the Maths.
Most scientific talks begin with context. This one very soon focused on a number. And once David J. Gross had explained what that number meant, the main hall of Lindau Inselhalle fell very quiet.
A Warning That Started in 1955
Seventy-one years ago, in the early years of the Lindau Nobel Laureate Meetings, eighteen physicists gathered on the island of Mainau and signed a declaration warning the world about nuclear weapons. Among them were Otto Hahn, who discovered nuclear fission, Werner Heisenberg, and Max Born. Their conclusion was stark: if nations did not renounce force as a final resort, they would cease to exist. The world listened. Arms control treaties followed, reducing the number of deployed nuclear weapons from roughly 70,000 at the height of the Cold War to a fraction of that figure. Then, one by one, those treaties disappeared.
At the 75th Lindau Nobel Laureate Meeting, three Nobel Laureates took to the stage to explain what this means today – and to challenge the 600 Young Scientists in the audience to become part of the solution. The discussion was moderated by Lindau Alumnus 2019 Sébastien Philippe, 2025 MacArthur Fellow, Scientific Secretary of the United Nations Independent Scientific Panel on the Effects of Nuclear War, and Assistant Professor of Nuclear Engineering and Engineering Physics. Drawing on his expertise at the intersection of nuclear security and science policy, Philippe provided structure to a discussion that spanned the historical legacy of the Cold War, today’s geopolitical realities, and the emerging challenges posed by artificial intelligence.
“Totally Insane” – And Getting Worse
David J. Gross, co-initiator of the 2024 Mainau Declaration on Nuclear Weapons, opened with facts that are difficult to absorb. At the height of the Cold War, around 70,000 nuclear weapons were deployed worldwide, many on 20-minute alert. Each was approximately 100 times more powerful than the bomb dropped on Hiroshima. Arms control treaties reduced that number by a factor of seven.
Today, however, virtually every major disarmament agreement concluded over the past fifty years has either been terminated, allowed to expire or abandoned without renewal.
“We are in the middle of an arms control race and an arms race, and there are many potential nuclear states who are seriously considering building the bomb of their own for the first time.“ Gross presented this not as political rhetoric but as mathematical reality. He added that nine additional states are now seriously considering developing nuclear weapons. In his assessment, the annual probability of nuclear war has risen to around two percent. The implication takes a moment to process.
„So that is the reason I have concluded that the risk of nuclear war has increased, might be of the order of 2 % now, and that makes a big difference. The half-life is then 34 years, which affects all of the Young Scientists here with the probability that half of your lifetime has now been shortened considerably. Not to speak of the lifetime of my children and my grandchildren.“
Among the predominantly Young Scientists in their twenties and thirties in the audience, the room fell silent.
Why Deterrence No Longer Works
Gross then turned to game theory to explain why today’s strategic landscape differs fundamentally from that of the Cold War. The doctrine of Mutually Assured Destruction (MAD) – the strategic logic that prevented two superpowers from pressing the nuclear button – maintains a grim internal coherence only when exactly two dominant actors confront one another. With three nuclear powers, that logic begins to collapse. With nine – or potentially eighteen – it has no stable equilibrium at all.
“The world is multipolar, if you haven’t noticed. The idea of mutually assured destruction works somewhat if you have two superpowers. I see no way it has any fixed point but disaster if you have three, and certainly if you have nine, and even more if you have 18.“ Gross also warned that the communication channels and trust-building mechanisms painstakingly developed during the Cold War have largely disappeared.
When Artificial Intelligence Enters the Equation
E. Moerner, Nobel Laureate in Chemistry 2014, extended the discussion into territory that the signatories of the 1955 Mainau Declaration could scarcely have imagined: artificial intelligence. War-gaming simulations involving AI systems, he explained, have consistently produced an alarming pattern. The models almost invariably escalate conflicts towards the nuclear option.
“But if it’s wrong, who’s accountable? Who’s responsible for the screw up, for the mistake? And that has not really been placed in position yet and needs to be.“
The question is anything but rhetorical. As Moerner acknowledged, no satisfactory answer currently exists. The position of the Nobel Laureate Assembly for the Prevention of Nuclear War is therefore unequivocal: at least two human beings must remain involved in any decision concerning the use of nuclear weapons. Delegating such decisions entirely to autonomous systems is unacceptable.
What World Leaders Could Do – Right Now
The three Nobel Laureates did not come to Lindau merely to issue a warning. They also presented a concrete agenda for action. The Nobel Laureate Assembly, now supported by 129 Nobel Laureates and numerous experts in nuclear security, has put forward a series of policy recommendations:
- reaffirm the global moratorium on nuclear testing;
- begin immediate negotiations between Russia and the United States on a successor to the expired New START Treaty;
- include China in future nuclear arms control negotiations; and
- ensure meaningful human control over every stage of nuclear decision-making.
Brian P. Schmidt, co-initiator of the 2024 Mainau Declaration, concluded with a passionate call for action to the Young Scientists: „We’re actually looking for your advice as well. There are, you know, 88 different cultures here. […] There is not one world leader, not one who says nuclear war is a good thing. Everyone actually has the same goal to lower it. And the question is, how do we have that conversation across the 197 countries of the world? I’m looking for inspiration from you. We do not have all the answers.“
The Question Gross Left Open
Towards the end of the session, Gross returned to the number that had opened it:
Thirty-four years. He acknowledged that the estimated annual probability of two percent is just that – an estimate. It is imprecise, open to debate and difficult to verify. His team intends to refine the calculation. But the overall direction, he argued, is beyond dispute. And the half-life of a civilisation is not the kind of figure that improves simply because we choose to ignore it.
Everything else that was said in Lindau is also on the record: The Threat of Nuclear War – watch the full session in the Lindau Mediatheque.
This blog post is part of a series showcasing highlights from #LINO75. Most of the Scientific Programme from the recent Lindau Meeting is available in the Lindau Mediatheque.
