Isidor Isaac Rabi

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Of Judaism, but Not in It

A Nobel Prize winning physicist who helped build the atomic bomb had a deep and abiding relationship to his Orthodox Jewish upbringing

Avi Shafran
August 22, 2023
Isidor Isaac Rabi

Science History Images/Alamy

On July 16, 1945, J. Robert Oppenheimer stood in the Jornada del Muerto desert in New Mexico, watching a second sunrise—that caused by the detonation of the world’s first nuclear explosion, marking the dawn of the atomic age.

Standing by his side was I.I. Rabi, another Jewish physicist. “It was a vision,” Rabi later said of that explosion. “Then, a few minutes afterward, I had gooseflesh all over me when I realized what this meant for the future of humanity.”

If Oppenheimer was the Jewish father of the bomb, it had a large assortment of Jewish uncles (and at least one aunt, Lise Meitner), including Edward Teller, Leo Szilard, Niels Bohr, Felix Bloch, Hans Bethe, John von Neuman, Rudolf Peierls, Franz Eugene Simon, Hans Halban, Joseph Rotblatt, Stanislav Ulam, Richard Feynman, and Eugene Wigner.

Judaism qua Judaism, however, wasn’t a major part of the lives of most, if not all, of those Jewish scientists. Certainly not of Oppenheimer’s.

But Judaism was central for Rabi, who was a close colleague and friend of Oppenheimer’s, and who was vital to America’s efforts to develop the atomic bomb.

In 1930, Rabi researched the nature of the force binding protons to atomic nuclei. That work eventually led to the creation of molecular-beam magnetic-resonance detection, for which Rabi was awarded the Nobel Prize in physics in 1944. Rabi’s work is what made magnetic resonance imaging, or MRI, the valuable diagnostic test, possible.

During World War II, Rabi served as associate director of the Radiation Laboratory—which became known as the “Rad Lab”—at MIT, where he was one of the first scientists in the U.S. to work on what is known as a cavity magnetron, a device that sends a stream of electrons, guided by a magnetic field, past a series of cavity resonators—small, open cavities in a block of metal. The electrons cause microwaves to oscillate within, much the way air blown through a whistle produces a tone. The microwave-generating device revolutionized radar (and today, rather mundanely, is part of every microwave oven).

The ability to produce shorter, or micro, wavelengths through the use of the cavity magnetron on ships and aircraft resulted in unprecedented accuracy in locating enemy craft over greater distances. The Second World War’s main theater of operations was, in effect, a massive sea and air battlefield that stretched for thousands of miles. Many military historians give the lion’s share of credit for the Allies’ victory on that global battlefield to the greatly enhanced radar system honed by Rabi and others at the Rad Lab.

The other decisive technology of the war was, of course, the atom bomb, two of which devastated the Japanese cities of Hiroshima and Nagasaki.

During the first test bomb’s gestation, Oppenheimer offered Rabi, with whom he had become friendly, the position of deputy director of the Manhattan Project. Rabi turned it down, though he agreed to serve as a consultant for the project and made occasional trips to work at Los Alamos. Rabi was with Oppenheimer for the Trinity test on that historic July morning.

If Oppenheimer was the father of the bomb, it had a large assortment of uncles (and at least one aunt, Lise Meitner), and many, like Oppenheimer, were Jewish.

Oppenheimer was not oblivious to his connection to other members of the Jewish tribe. When news of the mass murder of Jews in Europe reached him, he was deeply shaken, feeling a bond of ethnicity with Hitler’s victims. “I had a continuing, smoldering fury,” he wrote, “about the treatment of Jews in Germany.” And, while teaching at Berkeley just before the creation of the Manhattan Project, he earmarked 3% of his salary to help Jewish scientists escape Nazi Germany.

But, as far as Judaism as a religion was concerned, Oppenheimer’s convictions mirrored those of the Society for Ethical Culture, the Jewish-founded but wholly secular movement in which he was raised. As Elie Wiesel wrote in a review of a play based on American Prometheus, the book that inspired the current popular film: “Despite being a notable Jew, [Oppenheimer] remained at a distance from Yiddishkeit.”

Rabi, however, despite his friendship with Oppenheimer, was a very different sort of Jewish physicist. Though he respected his colleague greatly, Rabi told his biographer, John S. Rigden, that Oppenheimer “was Jewish, but he wished he weren’t, and tried to pretend he wasn’t.” Rabi was saddened by his friend’s apathy toward his Jewishness and saw it as having caused Oppenheimer to have failed to become a fully “integrated personality.”

The contrast between the two men’s attitude toward their Jewishness is evident in how Oppenheimer, as an 18-year-old in 1922, accompanying his English teacher Herbert Smith on a trip to the Southwest, asked to travel as Smith’s brother so he could be introduced as “Robert Smith.”

Rabi, too, as a young man, during the two postdoctoral years he spent in Europe, sought to amend his name, but in the other direction. In Germany, he insisted on being identified as Isidor Isaac Rabi. “I was never sailing under false colors,” he explained about that decision. “This is it. Whatever dealings we have will be on that basis—I know who you are and you’ll know who I am.”

Though proud of his religious heritage, Rabi never dressed or lived as an observant Jew. His appearance and demeanor in every way telegraphed an image of the secular scientist. But his mindset, when it came to Judaism, was considerably more complex.

From left: Robert Oppenheimer, Isidor Rabi, H.M. Mott-Smith, and Wolfgang Pauli at Lake Zurich, Switzerland
From left: Robert Oppenheimer, Isidor Rabi, H.M. Mott-Smith, and Wolfgang Pauli at Lake Zurich, Switzerland

AIP Emilio Segrè Visual Archives, Fermi Film Collection

Rabi was born in 1898, into an observant Orthodox Jewish family, in Rymanów—what was then part of Austrian-ruled Galicia and is today part of Poland. At his circumcision, he received the name Yisrael Yitzchak. Soon thereafter, his family emigrated to the U.S., settling into a small apartment on Manhattan’s Lower East Side before moving to the Brownsville neighborhood of Brooklyn.

Rabi’s parents fully maintained and cherished their Orthodox Jewish observance, and the family spoke Yiddish exclusively.

As a young boy, though, Yisrael Yitzchak quickly picked up English, and his interest in science led him to the public library and to tinkering with electronics. He was no mere dabbler. His first scientific paper, on the design of a radio condenser, was published in Modern Electrics when he was still in elementary school.

And his scientific explorations were not limited to any one field. When he read about heliocentrism, like many a young person coming to doubt the wisdom of his parents’ life choices, “Izzy”—how he came to be known at school—proudly declared himself an atheist. “It’s all very simple.” he informed his parents. “Who needs God?”

They were disappointed, as might be expected, but tolerant. He was only a boy, after all. And when his bar mitzvah approached, they asked him to prepare a bar mitzvah drasha. This was usually a scholarly discourse on a topic sourced in the Talmud for the guests, who were all religious people like Rabi’s parents. Rabi eventually agreed. And delivered a speech—in Yiddish—about how an electric light works.

“I talked about the carbon filament,” he recalled in his later years, “and then there was something I thought was very clever: getting the [electrical] lead out from the filament.”

Despite his 13-year-old freethinking ways, Rabi, even as a youth, came to mature in his worldview. And to feel the sense of awe that underlies deeply religious minds.

To be sure, he told Rigden, “When you are Orthodox, you say prayers for the new moon … [but] when you have an astronomical explanation, the rising of the moon becomes a sort of non-event.”

And yet, he recounted how, once he “was walking along and looked down the street, which was facing east. The moon was just rising. And it scared the hell out of me! Absolutely scared the hell out of me.” His inexplicable reaction to the grandeur of a moonrise was at odds with cold rationalism.

Many decades after his boyhood, he recalled how intrigued he had been as a youth, even an ostensibly atheist one, by the biblical creation account. “The first verses … were very moving to me as a kid. The whole idea of the Creation—the mystery and the philosophy of it. It sank in on me, and it’s something I still feel.”

“My early upbringing, so struck by God, the maker of the world, this has stayed with me,” he mused. “The idea of God,” he added, “helps you to have a greater feeling for the mystery of modern physics.”

Rabi expressed disdain for physicists who pursue their occupation for fun. “I knew other ways to have fun,” he said, drolly. “Physics has a much deeper emotional quality for me than that.”

Rabi considered physics as something that “transcended religion,” but didn’t replace it. Physics, he explained, “filled me with awe, put me in touch with a sense of original causes. Physics brought me closer to God.”

He recounted that whenever one of his students would come to him with a scientific project, he asked “only one question: ‘Will it bring you nearer to God?’” And, he added, “They always understood what I meant.”

‘My early upbringing, so struck by God, the maker of the world, this has stayed with me.’

After the war, Rabi returned to Columbia University, where he had taught in the 1930s. He became an outspoken critic of the continued development of nuclear weapons, joining with Oppenheimer and Enrico Fermi to oppose the development of the hydrogen bomb, 1,000 times more destructive than the bombs that had fallen on Hiroshima and Nagasaki.

A plan he had put forth to enlist all nations in forswearing development of such a weapon fell flat at the United Nations when the Soviet Union refused to be part of it.

In his final days, Rabi had the bittersweet experience of undergoing an MRI examination, the medical fruit of his prewar research. He was approaching death’s door—through which he passed on Jan. 11, 1988—but could take heart at what he had bequeathed to help save, not take, lives. “I saw myself in that machine,” he exulted. “I never thought my work would come to this.”

Rabi never returned to the Orthodox practice of his family and his youth. And yet, at the same time, he remained somehow conjoined with it. “Nothing in the world can move me as deeply as some of these Orthodox Jewish practices,” he confided.

“People go to Israel, to Williamsburg in Brooklyn, or to those places where Orthodox Jews go … and they pray and shake back and forth. Some people are appalled by it, but to me it is great. These are my people. I could join them, shake back and forth, and feel all right about it.”

He paused then to reassure his biographer that “I’m a scientist, which I firmly believe transcends—doesn’t oppose, but transcends—these particular things. I am of this … there is no question, but I’m not in it, couldn’t be in it. I love it and I respect it, but as a scientist I am at a more universal level … and this comes back to God.”

“Of this but not in it.” An apt capture of the subtle complexity of Rabi’s feelings toward his religious roots. What he realized was the truism that a scientific mindset needn’t preclude a spiritual one, indeed can be based on one. Human lives are lived in color, not black and white.

And so, while J. Robert Oppenheimer may have epitomized the “pure” scientist, his friend Rabi was, psychologically speaking, to borrow a phrase, a man in full.

In a revealing, pithy attestation, Rabi told his biographer: “There’s no question that basically, somewhere way down, I’m an Orthodox Jew [...] In fact, to this very day, if you ask for my religion, I say ‘Orthodox Hebrew’—in the sense that the church I’m not attending is that one. If I were to go to church, that’s the one I would go to. That’s the one I failed. It doesn’t mean I’m something else.”

Rabbi Avi Shafran is a columnist for Ami magazine and writes widely in other Jewish and general media. He also serves as Agudath Israel of America’s director of public affairs.