A history of substance

Michael Gordin applauds a study tracing the tumultuous 70-year trajectory of condensed-matter physics.

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Femtosecond laser systems, which emit ultrashort optical pulses, are used to probe fundamental properties of solid-state materials.Credit: NREL/DOE

Solid State Insurrection: How the Science of Substance Made American Physics Matter Joseph D. Martin University of Pittsburgh Press (2018)

O que é "física"? Desde o nascimento da era nuclear, no final da Segunda Guerra Mundial, a física tem sido frequentemente retratada como a busca para penetrar no átomo; adivinhar os segredos do reino subnuclear de mésons e quarks com aceleradores cada vez mais impressionantes e detectores de partículas cada vez mais gigantescos. A física de alta energia era o material glamouroso que atraía prêmios Nobel e uma ampla cobertura da imprensa. A maioria dos livros sobre a história da física considera a espinha dorsal do campo.

Studying elementary particles is not, however, what most physicists do. By almost all metrics — PhD degrees, articles in flagship journals, memberships in professional societies — the majority were not, and are not, high-energy physicists. Instead, they plough the furrows of what was once known as solid-state physics — better known since the 1970s as condensed-matter physics. This is the science that brought us superconductivity, superfluidity, magnetic memory, liquid-crystal displays and more.

This is the physics that the science historian Joseph Martin presents in Solid State Insurrection — but his focus is not those landmarks. For him, “physics is what physicists decide it is”. This is not some slogan of radical relativism. It is a recognition that physics is a profession, and it is the business of professional groups to police their boundaries.

Condensed-matter physicist Philip Anderson of Bell Labs, who shared the Nobel Prize for Physics in 1977.Credit: Bettmann/Getty

Nos Estados Unidos, a motivação de grande parte desse policiamento foi o acesso ao financiamento: os físicos de alta energia receberam muito do governo e os físicos do estado sólido foram desviados para a indústria. Durante décadas, a condescendência floresceu de um lado e o ressentimento infestou do outro. Os assuntos chegaram ao auge em uma decisão do Congresso de cancelar o que teria sido a joia da coroa da física de alta energia dos EUA, Superconducting Super Collider (SSC), em 1993. Esse cancelamento foi influenciado por críticas perante comitês do Congresso de eminentes condensados. especialistas em matéria, como o ganhador do Prêmio Nobel, Philip Anderson, da Bell Labs.

Essa disputa era mais do que recursos. Já na década de 1970, físicos de estado sólido como Anderson e Alvin Weinberg haviam articulado uma visão alternativa da ciência da física. Os físicos de partículas justificaram-se através de um compromisso com a "ciência pura" que datava das origens da American Physical Society (APS) no final do século XIX. Como a física de alta energia sondava os menores constituintes da matéria, um reducionista diria que essa física era a mais "fundamental". Anderson discordou. Como Martin explica em um excelente capítulo, para Anderson, “física fundamental” era sobre ferromagnetos, bem como sobre quarks.

Then came the SSC. “The original Star Wars trilogy tells the story of a ragtag band of misfits, many of whom are adept at manipulating a force pervading in everyday matter, who ally to mount an insurrection against the established order and help destroy a giant, partially built beam machine,” writes Martin. The trajectory of US solid-state physics, he notes, “followed much the same plot”. Although he concedes that the SSC was more drastically affected by the end of the cold war than by intradisciplinary critique, there is no doubt where Martin’s sympathies lie.

Solid-state physicist Alvin Weinberg (left), director of the Oak Ridge National Laboratory in Tennessee, talking to Senator John F. Kennedy in 1959.Credit: Ed Westcott/DOE

He devotes most of his book to a detailed reconstruction of the intense struggle, half a century earlier, for recognition by solid-state physicists against the leadership of the APS, which was itself frustrated and challenged by the rapid growth in their ranks during the 1940s. Physicists who worked on metals, ceramics and other domains straddling fundamental and applied physics wanted representation at APS meetings, leading to the creation of the Division of Solid State Physics in 1947. The institutional gerrymandering had significant implications for the APS, especially for its flagship journal, Physical Review. (Publishing is a fascinating leitmotif in Martin’s account.)

This organizational innovation was achieved only after substantial resistance from some APS stalwarts, who perceived the purity of their ranks as becoming sullied by industrial scientists. The stalwarts included Harvard University’s John Van Vleck, even though he had trained many of the leaders of the next generation, including Anderson. Van Vleck’s objections were littered with political language: he protested against the “Balkanization” of the APS, and he thought the solid-state division was a “new-deal-bureaucratic” scheme that ought to be resisted. The conservative Van Vleck was unhappy about the direction that the United States — and with it physics — was going.

This raises a broader point about Martin’s engaging book: the politics in it are exclusive to the profession. He keeps his gaze tightly trained on physicists as they define physics to each other. The Vietnam War (and scientific work in support of it), anti-Communism, civil rights and other political fault lines — which affected physicists no less than other citizens — are mentioned in passing, if at all. Yet they must have mattered. Physics is defined not just by what physicists decide it is, but by what the broader society will (or won’t) support. That decision is made within the halls of the APS, but also in those of Congress.

Construction of the Superconducting Super Collider, a US high-energy physics project, was cancelled by Congress in 1993.Credit: SSC Lab./SPL

Nature 561, 306-307 (2018)

doi: 10.1038/d41586-018-06696-4