Zwicky: New Lens on an We Won’T Notice the Difference

COMMENT BOOKS & ARTS

framework of quantum mechanics ASTROPHYSICS inspire Carroll to call it the “courageous” approach. Don’t worry about those extra worlds, he asserts — we can’t see them, and if the many-worlds theory is true, Zwicky: new lens on an we won’t notice the difference. The many other worlds are parallel to our own, but so hidden from it that they “might as well elusive astrophysicist be populated by ghosts”. Jaco de Swart enjoys a biography of the scientist who BRANCHING CATS pioneered findings on dark matter and supernovae. For physicists, the theory is attractive because it explains many puzzles of quantum mechanics. With Erwin Schrödinger’s ritz Zwicky advanced astronomy over presented his findings thought experiment concerning a dead- much of the twentieth century, pio- in the journal of the and-alive cat, for instance, the cats simply neering findings on constituents of Swiss Physical Soci- branch into different worlds, leaving Fthe cosmos from supernovae and neutron ety. However, it took just one cat-in-a-box per world. Carroll stars to dark matter and compact galaxies. another three dec- also shows that the theory offers simpler He worked at two of the world’s most his- ades for the phenom- explanations of certain complex phenom- torically important observatories: Mount enon to be observed ena, such as why black holes emit radia- Wilson and Palomar in California. He was widely. And only after tion. Furthermore, the theory might help an early innovator in jet-engine design. Yet Zwicky’s death, in to develop still-speculative ideas about the Swiss astronomer is a somewhat elusive Zwicky: The 1974, was dark matter conundrums such as how to combine figure in the history of science. Science jour- Outcast Genius accepted as part of the quantum mechanics with relativity theory. nalist John Johnson seeks to rectify that in Who Unmasked cosmological canon, Something Deeply Hidden is aimed at his spirited biography, Zwicky. the Universe through the work of non-scientists, with a sidelong glance As Johnson reveals, the very boldness and JOHN JOHNSON radio astronomers, at physicists still quarrelling over the ingenuity of Zwicky’s discoveries could work Harvard (2019) cosmologists and par- meaning of quantum mechanics. against him: many were viewed as unconven- ticle physicists. Carroll brings the reader up to speed tional, and were confirmed only years after Zwicky’s star soon rose. In 1934, he and on the development of quantum phys- he made them. Zwicky also had a reputation Walter Baade identified the existence of ics from Max Planck to the present, and for abrasiveness. For instance, he reportedly supernovae, the explosive final stage of explains why it is so difficult to interpret, called some of his colleagues at the California a star’s life. Zwicky posited that novae before expounding the many-worlds Institute of Technology (Caltech) in Pasadena launched a sea of particles into space that theory. Dead centre in the book is a “spherical bastards” (meaning, from which- might account for cosmic rays, the then- “Socratic dialogue” about the theory’s ever angle you looked at them). Johnson’s unexplained phenomenon observed by implications. This interlude, between book unravels these two sides of Zwicky — Nobel laureate Victor Hess in 1912, during a philosophically sensitive physicist the brilliance and the ire — by framing him experiments conducted in a balloon. When and a scientifically alert philosopher, is as an “outcast genius”. But can this portrayal the theory was made public, Zwicky’s career designed to sweep away intuitive reser- help to change perceptions of the prolific exploded, and he became “the darling of vations that non-scientists might have. astrophysicist? reporters everywhere”, Johnson writes. Nevertheless, non-scientists might have Zwicky trained in physics and mathemat- Johnson touches on many other examples lingering problems with Carroll’s breezy, ics at the Swiss Federal Institute of Tech- of Zwicky’s prescience during his Caltech largely unexamined ideas about “reality”. nology in Zurich. In 1925, the Rockefeller years. Again with Baade in 1934, he predicted Like many physicists, he assumes that Foundation in New York the existence of neutron stars, extremely reality is whatever a scientific theory says City offered him a fellow- “Zwicky is dense bodies of neutrons left behind after a it is. But what gives physicists a lock on ship to study the physics celebrated supernova. In 1937, he was the first to argue this concept, and the right to say that the of crystals at Caltech with mainly as that galaxies, like stars, could act as gravi- rest of us (not to mention, say, those in the Nobel-prizewinning the ‘father tational lenses, bending light according to extreme situations such as refugees, sol- experimental physicist of dark Albert Einstein’s general theory of relativ- diers and people who are terminally ill) Robert Millikan. Two years matter’.” ity. And in the 1940s, his search with Milton are living through a less fundamental later, he shifted fields. He Humason for white dwarfs — another class reality? Could it be that we have to follow began to research galaxies at Mount Wilson of dense stellar remnants — gave early hints Heisenberg’s lead? That is, must we rely on alongside Edwin Hubble, the astronomer of the highly energetic outbursts that came to tools for talking about the complexities of who would find evidence for the expansion be known as quasars. Johnson tells the story reality that philosophers have developed of the Universe in 1929. Zwicky himself soon well, but does not delve much into the science over millennia to explain why the fox has produced a series of intriguing theories and behind the insights. such a tough time reaching those grapes? observations. As a scientist, Zwicky went his own way, What a wacky idea. ■ Zwicky is celebrated mainly as the ‘father of tending to study phenomena outside trends dark matter’. In the early 1930s, while studying in stellar astrophysics. His professional Robert P. Crease is chair of the Hubble’s observations of the Coma Cluster of animosities, however, were actively divi- Department of Philosophy at Stony Brook galaxies, he noted an anomaly. According to sive. Johnson notes that Zwicky despised University, New York. His most recent the measure of visible mass, single galaxies what he saw as unoriginal “grey thinking” book is The Workshop and the World: were moving too fast for the cluster to remain in fellow researchers. He called theoreti- What Ten Thinkers Can Teach Us bound together. Zwicky posited that an as- cal physicist Richard Feynman a “spiritual About Science and Authority. yet unobserved type of mass, dunkle Materie coward”, and was contemptuous of astro- e-mail: [email protected] (dark matter) might explain it, and in 1933 he physicists who adhered to the theory of an

BOOKS & ARTS COMMENT

Fritz Zwicky at the Schmidt telescope at Palomar Observatory, California, in the 1930s.

expanding Universe. Johnson contends that For instance, in 1943, he used the method the person as a product of their era. after Zwicky’s retirement in 1968, he was in researching and developing a jet engine Readers seeking that understanding barred from using the telescopes at Mount at Aerojet, a rocket-manufacturing com- might find Johnson’s book too anecdotal, Wilson and Palomar, owing to a quarrel with pany that at the time was based in Pasadena, and lacking in the context needed for an Hubble’s protégé Allan Sandage. California. It worked. Zwicky became a integrated portrait. Zwicky was part of a Johnson reveals other facets of the force in US rocket science, and in 1945 he new generation of early-twentieth-century astronomer. He points to Zwicky’s dedica- was the first to interview Werner von Braun astrophysicists, probing the cosmos beyond tion to his family, and his determination to — the engineer of the German V-2 rocket the Milky Way. And he was an émigré in PALOMAR OBSERVATORY/CALTECH PALOMAR use science as a tool for human progress. who became a crucial asset to the US space a war-torn era. If Johnson had more thor- Along with his extraordinary discover- programme. Zwicky’s contributions to the oughly explored what linked the man and his ies, Zwicky formulated schemes such as US Air Force were considered so valuable work to these historical developments, what turning asteroids into habitable planets that he received the Medal of Freedom from insights might have emerged? and — in another discerning moment — then-president Harry Truman in 1949. To some degree, then, Zwicky remains colonizing the Moon. Just as inventive Zwicky also wrote several books on his elusive. Nevertheless, Johnson’s book is rich was his methodology, which he dubbed methodology. In the 1971 Jeder ein Genie enough to inspire interesting meditations on “morphological analysis”. In essence, this is (‘Everyone a Genius’), he argued for mor- research, idiosyncrasy — and reputation. ■ a problem-solving technique for exploring phological analysis as a universal technique all possible solutions to any complex issue, for developing intellectual prowess. However, Jaco de Swart is a historian of science at from learning languages to computing genius is a slippery concept, and Johnson’s the University of Amsterdam. He works on astrophysical quantities. Although John- use of the term to describe Zwicky is risky. the history of the dark-matter problem and son does not describe it in depth, Zwicky A genius is a person apart, a ‘wonder’ who has co-authored a review titled ‘How dark clearly found it essential to doing good, evades explanation. The characterization is matter came to matter’. creative science. distancing, hindering our understanding of e-mail: [email protected]