Reviews physicsworld.com

Andrew Robinson The tempestuous genius of Fritz Zwicky Zwicky used to recount this story about Millikan often, writes John Johnson Jr, a prize-winning sci- ence journalist formerly with the Los Angeles Times, in his new book Zwicky: the Outcast Genius Who Unmasked the , a detailed and insightful biography. The story AIP Emilio Segrè Visual Archives certainly captures both the way in which Zwicky liked to see himself and the way in which some leading physicists responded to him. Others, however, took offence and did their best to ignore the astronomer, both during his lifetime and afterwards – one of the reasons why he is largely forgotten today. Indeed, Johnson’s book is the first biography to be writ- ten in English since the astronomer’s death aged 75 in 1974. Zwicky had a “preternatural abil- ity to welcome opposition as proof that he was on the right track”, writes Johnson in an excellent introductory chapter. “It was a characteristic that would underpin all the accomplish- ments of his working life, one that would bring him both honour and calumny,” the author writes. “It lay behind his prediction of [also in 1933]…And it was critical to his research into jet propulsion and rocket fuels during and after the Difficult and “I have read every paper you ever – a phenomenon first Second World War, which helped enigmatic wrote, I have listened to every pres- observed by Chinese astronomers in transform the humble rocket, a toy Fritz Zwicky feuded entation you have ever given, and I 185 AD – as a new category of astro- of backyard dabblers, into ballistic with many leading can tell you quite categorically that nomical object. When a supernova missiles capable of ending life on scientists of his day. I have never found a single original flares up, they suggested, it “repre- Earth and carrying astronauts to He is shown here at idea that you could honestly call sents the transition of an ordinary the Moon.” the your own.” That’s what Swiss physi- star into a , consisting It also contributed to Zwicky’s Institute of cist Fritz Zwicky once said when mainly of neutrons” (a particle that reputation as a difficult, enigmatic Technology in 1931. he was just 32, to Nobel laureate had been identified just one year man. “Feuding with many of the Front row (from left): Robert Millikan. Despite the fact earlier). It also becomes the source important scientists of his day, he Robert Oppenheimer, that Zwicky was yet to establish his of the then-mysterious cosmic radia- inspired so much resentment that Harry Bateman, scientific reputation at the time, tion detected on earth. after his death his critics did all they Richard Tolman, Millikan – who was the head of For decades, this theory was con- could to forget or disparage what he William Houston, Zwicky’s laboratory at the California troversial, until neutron stars were had done. Like the great forces he Robert Millikan, Institute of Technology (Caltech) – detected in the form of in chronicled, Fritz Zwicky distorted , Paul simply responded: “All right, how 1967 by Antony Hewish and Jocelyn the orbits of everyone who came in Sophus Epstein, about you?” Bell. In his 1994 book Black Holes contact with him, attracting many, Zwicky, Ernest “I have an original idea every and Time Warps: Einstein’s Outra- driving just as many away.” Charles Watson. two years,” replied Zwicky. “I’ll go geous Legacy, Caltech’s Among his supporters appears to further: you name the subject, I’ll described the Baade/Zwicky Stan- have been Albert Einstein, who is Zwicky: the Outcast come up with the new idea.” “All ford presentation and their sub- said to have taught Zwicky in Swit- Genius Who right young man,” said Millikan. sequent five-page research paper, zerland during the First World War. Unmasked the “Astrophysics.” “Cosmic rays from super-novae” In the US – to which Zwicky emi- Universe Three years later, at a dramatic (PNAS 20 259) as “one of the most grated in 1925 to join Caltech – jour- John Johnson Jr meeting in Stanford University in prescient documents in the history nalists called him Einstein’s “most 2019 Harvard 1933, Zwicky, along with the astron- of physics and ”. It was promising” pupil, perhaps borrow- University Press omer from the Mount essentially the birth of high-energy ing the phrase from Zwicky. Accord- 352pp £28.95hb Wilson Observatory, proposed the astrophysics. ing to him, Einstein once told him

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with reference to his own search for a Ground in New Mexico in his first unified field theory, that the theory’s Zwicky had a (failed) attempt to penetrate space. aim was “to obtain a formula that Regrettably, Johnson gives us little will account in one breath for New- preternatural idea of how Zwicky and von Braun, ton’s falling apple, the transmission the former Nazi, interacted at a of light and radio waves, the stars, non-technical level. Given Zwicky’s and the composition of matter”. It ability to welcome abrasive comments on so many of sounds like Einstein – though maybe his scientific colleagues – “horses’ with a soupçon of Zwicky. opposition as asses”, “spherical bastards”, by way Like Einstein after 1933, Zwicky of (mild) example – one suspects a settled in the US. But unlike Ein- proof that he was degree of empathy between him and stein he revisited Europe, even edu- von Braun, based on their joint fas- cating his children in Switzerland cination with science and technology while living in California. However, on the right track regardless of its ethical implications. he refused to take American citizen- “Once the rockets go up, who cares ship, which caused him difficulties where they come down?/ That’s not during the “Red Scare” of the 1950s, my department, says Wernher von despite his very public opposition Braun” wrote Tom Lehrer in his to Communism. classic song of 1965 (not quoted by He also visited Germany in the Johnson). Zwicky was never a man immediate aftermath of the war, and willing to compromise with others conducted extensive interviews with in order to fulfil his own promise. If German rocket scientists, including he had been, concludes Johnson, “he General Walter Dornberger, the wouldn’t have been Fritz Zwicky”. man in charge of the Peenemünde Army Research Centre – where Andrew Robinson is the author ofEinstein on the V-2 rocket was developed – and the Run: How Britain Saved the World’s Wernher von Braun, who became Caltech – Millikan’s son) were the Greatest Scientist (2019 Yale University a key figure in the American space first to question von Braun, in May Press) programme of the 1950s. Indeed, 1945. The following year, Zwicky Zwicky and two associates (one from used this knowledge to launch a V-2 ● See p44 for our review of Andrew General Electric, the other from rocket from the White Sands Proving Robinson’s latest book

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