## Physics History Puzzle

Which famous physicist once gave a lecture attended by a secret agent with a pistol, who would kill him if he said the wrong thing?

### 12 Responses to Physics History Puzzle

Might be Feynman?

2. Stephen Tedder says:

Heisenberg. But some of Moe’s stories might be a little exaggerated, if you know what I mean.

• Toby Bartels says:

That's enough info for me to find it with Google. Although the first hit looked a little off at first, it was correct.

3. Toby Bartels says:

I would guess someone from the Manhattan Project. Of course, there have been other secret technical military projects too. But maybe it's a trick question that has nothing to do with physics; shoot Einstein if he says something Zionist/pacifist/socialist that you're worried he'll say.

4. Wyrd Smythe says:

Drat! I would have guessed Oppenheimer.

5. arch1 says:

That’s quite a story. Was the physicist aware of the arrangement? Wild guess: Heisenberg (if allowed a 2nd it would be Sakharov).

6. John Baez says:

On 4 June 1942, Heisenberg was summoned to report to Albert Speer, Germany’s Minister of Armaments, on the prospects for converting the Uranverein’s research toward developing nuclear weapons. During the meeting, Heisenberg told Speer that a bomb could not be built before 1945, because it would require significant monetary resources and number of personnel.

After the Uranverein project was placed under the leadership of the Reichs Research Council, it focused on nuclear power production and thus maintained its kriegswichtig (important for the war) status; funding therefore continued from the military. The nuclear power project was broken down into the following main areas: uranium and heavy water production, uranium isotope separation and the Uranmaschine (uranium machine, i.e., nuclear reactor). The project was then essentially split up between a number of institutes, where the directors dominated the research and set their own research agendas. The point in 1942, when the army relinquished its control of the German nuclear weapons program, was the zenith of the project relative to the number of personnel. About 70 scientists worked for the program, with about 40 devoting more than half their time to nuclear fission research. After 1942, the number of scientists working on applied nuclear fission diminished dramatically. Many of the scientists not working with the main institutes stopped working on nuclear fission and devoted their efforts to more pressing war related work.

[…]

From 24 January to 4 February 1944, Heisenberg travelled to occupied Copenhagen, after the German army confiscated Bohr’s Institute of Theoretical Physics. He made a short return trip in April. In December, Heisenberg lectured in neutral Switzerland. The United States Office of Strategic Services sent agent Moe Berg to attend the lecture carrying a pistol, with orders to shoot Heisenberg if his lecture indicated that Germany was close to completing an atomic bomb.

There’s a reference for the last sentence:

• William Tobey, Nuclear scientists as assassination targets, Bulletin of the Atomic Scientists 68 (2012), 61–69.

The article says this:

#### The Heisenberg uncertainty and beyond

Targeting atomic scientists to retard a potential nuclear weapons program predates the existence of nuclear weapons. Alarmed by the possibility that the giant of German physics, Werner Heisenberg, was working on an atomic bomb for Adolf Hitler, noted theoretical physicist Victor Weisskopf consulted with Hans Bethe, a renowned colleague working in the Manhattan Project, in the autumn of 1942; Weisskopf subsequently corresponded with Robert Oppenheimer, then newly appointed to lead theoretical work for the Manhattan Project. According to Thomas Powers’s account in Heisenberg’s War, Weisskopf wrote, “I believe that by far the best thing to do in this situation would be to organize a kidnapping of Heisenberg in Switzerland” (Weisskopf, 1942). Over time, within the Manhattan Project and the Office of Strategic Services (OSS), Weisskopf’s proposal mutated into a plot to kill Heisenberg—a plot that very nearly came to pass.

Because much, although still not everything, about the plot to assassinate Heisenberg is known, and because it is no longer politically sensitive, the case is worth delving into in some detail, as it adds clarity to more modern cases. One key element in the problem that confronted the Allies during World War II, however, was very different from later episodes: No one could doubt that Heisenberg would greatly advantage any Nazi effort to build an atomic bomb. Powers relates Oppenheimer’s view in 1944 that “the position of Heisenberg in German physics is essentially unique. If we were [undertaking a bomb project] in Germany, we should make desperate efforts to have Heisenberg as a collaborator” (Powers, 1993: viii). What the Allies could not know were Heisenberg’s intentions, and they famously remain a matter of debate, and even drama, today (Frayn, 1998).

American and British officials initially ignored the suggestion of Weisskopf and Bethe that Heisenberg be kidnapped (Powers, 1993). But the seed was planted—and it sprouted into kidnapping plans 15 months later (Powers, 1993).

Physicist Niels Bohr escaped from Nazi-controlled Denmark in September 1943, bearing what the New York Times described—in an early leak of nuclear weapons-related information—as “plans for a new invention involving atomic explosions … of the greatest importance to the Allied war effort” (New York Times, 1943). What Bohr carried was a rough sketch given to him by Heisenberg during their famous 1941 Copenhagen conversation; Bohr took the sketch to be of a weapon, but it was most likely a nuclear reactor. During a two-day rail journey in December 1943 from Chicago to Lamy, New Mexico, Bohr convinced Brig. Gen. Leslie Groves, then in charge of the overall Manhattan Project, that the drawing was evidence of a German bomb program. Despite Oppenheimer’s “formal assurance” that the sketch did not depict a viable weapon, Groves concluded that he must act to blunt the Nazi effort (Powers, 1993: 246–248).

Groves contacted the OSS—the swashbuckling US agency then responsible for intelligence and covert action—and by February 1944, Special Operations Branch officers were forming improbable kidnapping plans that included flying Heisenberg from an anticipated snatch in Switzerland, parachuting with him into the Mediterranean Sea, and rendezvousing in the water with a surfaced submarine. The inherent danger of such an operation shows that Heisenberg’s survival was not a high US priority; indeed, if capture by German authorities were imminent, the plan was to kill him (Powers, 1993). Nothing, however, could be done until he was located. Before he could be, these kidnapping schemes—but not the desire to neutralize Heisenberg as a threat—were put aside (Powers, 1993).

In November 1944, the OSS learned that Heisenberg planned to visit Switzerland the next month. Former major league baseball catcher and then OSS officer Moe Berg was dispatched to Zurich with orders that “Heisenberg must be rendered hors de combat” (out of action) if Heisenberg gave evidence that the German bomb effort was close to completion. Apparently Berg alone was to decide whether or not to kill Heisenberg (Powers, 1993: 391–392).

With a pistol in his pocket, Berg attended a lecture by Heisenberg, waiting for some sign of an advanced German atomic bomb program. Heisenberg offered no such signal and therefore survived. Instead, Berg reflected on his own “uncertainty principle” in regard to killing Heisenberg, a reference to the scientist’s most prominent contribution to the theory of quantum mechanics (Powers, 1993: 398–399).

Later that week, as the Battle of the Bulge turned to Allied advantage, Berg attended a dinner given for Heisenberg and heard him lament Germany’s coming loss of the war. This appeared to clinch the case that Heisenberg could not be part of a successful atomic bomb project and effectively ended any further US interest in killing him (Powers, 1993).

The reference to Powers is:

• Thomas Powers, Heisenberg’s War: The Secret History Of The German Bomb, Alfred Knopf, New York, 1993.

7. Simplicio says:

Seems kind of weird to think that even if the Germans were on the verge of building a bomb, Heisenberg would say so, even obliquely, in a public lecture in a foreign country.

Berg was something of an exaggerator about his personal exploits, so while I’m sure the basic story about his seeing Heisenberg in Switzerland is true, I’d take the stuff about the OSS leaving it up to him whether to assassinate the scientist with a grain of salt.

• John Baez says:

Having not read Powers’ book on Heisenberg, I don’t know what evidence there is for this story.

8. $E=mc^2$

9. preskill says:

There is a book about Moe Berg: The Catcher Was a Spy, which was made into a 2018 film starring Paul Rudd. I read the book but haven’t seen the film (which was not very good, according to Rotten Tomatoes). The book is kind of interesting. Moe did indeed tend to embellish his stories, but the basic facts of the Heisenberg incident seem to be true.

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