“The half-life of humanity is currently about 35 years,” said Nobel Prize-winning physicist David Gross at the conclusion of an evening lecture at the Conference of the German Physical Society in Erlangen in March. In other words, the physicist estimates that in a little over three decades, there is a 50% chance that our species will disappear.
This alarming statement followed Gross’s estimate that the risk of nuclear war was increasing from 1 percent per year to about 2 percent per year. After the lecture, the audience was visibly thoughtful. The current global situation and the award-winning speaker’s warnings hung like a dark cloud over the participants.
“I’m still hoping that game theory will come to the rescue,” another physicist later told me at the conference. According to this reasoning, the rules of logic – provided everyone respects them – would prohibit a nuclear first strike.
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But looking at history, I’m not so optimistic. Unfortunately, people rarely act rationally. In addition, the founder of game theory, the brilliant Hungarian-American mathematician and physicist John von Neumannnot only helped develop the first atomic bomb, but also worked with the U.S. government to plan nuclear attacks against Japan. He even recommended a preemptive strike against the Soviet Union. The 20th century reveals that game theory offers a remarkable tool for solving problems, but that it does not in itself guarantee peace.
Basics of game theory
Von Neumann profoundly shaped many scientific fields in the 20th century, including information theory, quantum mechanics, and computer science. Contrary to stereotypes about introverted scientists, he was also known for his wild parties.
Reflection on strategy in various games would eventually lead to von Neumann’s 1928 book On board game theory (“On board game theory“, which caught the attention of economist Oskar Morgenstern. The two researchers began to compile and publish their joint thoughts on gambling strategies, resulting in the nearly 700-page book Game theory and economic behavior.
In game theory, different scenarios are considered and each is assigned a numerical value, for example between –10 and 10. A high value symbolizes a particularly advantageous situation for a particular player. The exact numerical values chosen for each situation are subjective. However, based on this subjective weighting, an optimal strategy can then be developed from an objective point of view.
To illustrate how game theory can be applied, consider a scenario in which two players are playing, for example, chess. To simplify things, imagine that Player A is evaluating two moves: targeting a pawn on square 1 or another pawn on square 2. The opponent, Player B, is also thinking defensively about how to react. Game theorists would assign numerical outcomes to different scenarios. For example, if player A manages to take square 1 without negative consequences, he will receive +10 points and player B will receive –10 points. If player A takes square 1 but immediately afterwards loses a valuable piece, then the result is –4 for player A and +4 for player B.
If you spend enough time thinking about these scenarios, you may notice that there is a risk of stuck in a decision-making loop. For example, player A knows that player B is likely to follow a particular course of action, but player B knows that player A also knows this and therefore might do the opposite. This little thought experiment turns into an endless spiral.
So one of the further steps that game theorists take is to rely on the idea that chance will be part of the process. In cases where there is no optimal decision, to avoid the loop of “I know what you think but you know what I think”, game theorists suggest imagining that a particular scenario will repeat itself several times. Then they ask which course of action is best for a particular player on average. You can represent the opponent’s response using a coin toss, for example, to determine what is likely to pay off. And you can add up the odds with a “skew coin” to explore the best strategy, assuming that the odds are not 50-50 for a particular answer, but that they lean more in your opponent’s favor than yours.
When theorists enter the war room
But game theory isn’t just about board games. It is about making scientifically based decisions and assessing the associated risks.
For example, in 1945, the United States wanted to force Japan to surrender as quickly as possible, before Stalin could intervene in World War II. The new American atomic bomb, whose development von Neumann had greatly influenced, seemed suited to this purpose. Still, the United States needed a strategy for this weapon. On the one hand, the targets had to be important from a military point of view; on the other hand, they should not be too obvious, so as not to prevent Japan from preparing for the attack. Japan and the United States were each trying to stay one step ahead of the other. At the same time, both nations had limited resources and had to choose between attacking or defending individual cities. American strategists considered five different target cities: Kokura, Hiroshima, Yokohama, Niigata and Kyoto.
We do not know precisely how these war decisions were made, but we do know that von Neumann was part of the target selection committee that ultimately determined that Hiroshima and Nagasaki would be bombed. Game theory would have been a logical approach to invoke because it helps people weigh various options.
Ultimately, the committee chose Hiroshima and Nagasaki. The destruction of these two cities went down in history as a horrible event. An estimated 200,000 people lost their lives. Ultimately, the United States achieved its goal: Japan surrendered.
With the end of World War II, the Cold War began. The nuclear arms race between the United States and the Soviet Union has begun. And von Neumann did not believe in a peaceful solution. It was certain that open nuclear war would break out between the two powers. He therefore advocated a nuclear first strike. “If you say, why not bomb [the Russians] tomorrow I say: why not bomb them today? If you say today at 5 p.m., I say why not at 1 p.m.? he would have said in 1950.
Today we know that it was a good decision to ignore von Neumann’s advice about bombing the Soviet Union. Fortunately, the Cold War ended without a catastrophic nuclear war.
But today, some 35 years after the end of the Cold War, the world once again finds itself in an era of open conflict involving countries possessing nuclear weapons. This makes 2024 Mainau Declaration on nuclear weapons, initiated by Gross and others with reference to the original Mainau Declaration of 1955 and signed by more than 100 Nobel laureates, is all the more important.
The statement urgently warns of the danger “that, either by accident or deliberate act, these horrific weapons could be used – with the likelihood of the end of human civilization as we know it.” And last year, the first-ever Assembly of Nobel Laureates for the Prevention of Nuclear War issued a separate statement suggesting concrete proposals for reducing the risk of nuclear war. For example, it states that at least two people are needed to order a nuclear attack; this is not the case in many countries (such as the United States or North Korea).
Hopefully, academics will be heard in this matter, even if things currently seem bleak.
This article was originally published in spectrum of science and has been reproduced with permission. It was translated from the original German version with the help of artificial intelligence and reviewed by our editors..
