Stuart Clark (2) (1967–)

La casualità delle mie scelte di lettura ha fatto sì che mi capitassero due libri di cosmologia d fila. In questo caso Clark fa una trattazione molto più ampia di quella di Balbi: non che si debba o voglia fare una graduatoria, perché i due approcci sono completamente diversi. Clark scrive molto bene ed è chiara la sua volontà di raccontare quello che succede ora nella cosmologia, e d'altra parte questo è il suo lavoro di scrittore scientifico. Quindi localmente è tutto bello e comprensibile, oltre che posto in un contesto storico che fa apprezzare meglio le cose e condito da aneddoti gustosi in stile americano come l'incontro brussellese tra Einstein e Lemaître. Quando però la lettura termina, rimane un senso di vuoto, non dovuto alla vastità dell'universo quanto alla eterogeneità dei temi trattati. La mia sensazione è che Clark abbia ripreso quanto aveva scritto sulle riviste e l'abbia inciccito; ma non l'ha ripensato in modo unitario. Risultato? Si scoprono tante nozioni puntuali, ma l'universo resta ancora più sconosciuto. Una nota positiva: è bello leggere di come gli scienziati lavorano, facendo ipotesi sempre più indirette. Spesso noi crediamo che quello che dicono gli scienziati siano verità assolute: qui si vede che non è proprio così. Buona la traduzione di Valeria Lucia Gili.… (mais)

Not bad, although the subtitle (“The Unexpected Tragedy of Richard Carrington and Tale of How Modern Astronomy Began”) is misleading. Richard Carrington is a major character but not the whole subject of the book, and it’s not about how modern astronomy began, or even about how solar astronomy began, but about the discovery of the relation between sunspots and space weather.

Longitude author Dava Sobel gets a cover blurb, and I suspect The Sun Kings was inspired by the success of her book. The general idea is similar; the British government sponsors research into a navigational problem (measurement of longitude versus reasons for periodic and long term compass deflection); a colorful cast of characters takes on the problem; and it’s eventually solved/explained. Carrington’s role was divided between the tedious but necessary grunt work of astronomy – careful observations and measurement of sunspots – coupled with the kind of luck that favors the prepared mind: the first recorded observation of a white-light solar flare. His tragedy was largely self-inflicted. First he alienated a number of professional astronomers by becoming convinced that the government owed him a paid position (to be fair, he was much more deserving of such a position than many of the successful job seekers); then he became obsessed with and married a much younger woman (whom he’d met walking on the street), Rosa Rodway. Ms. Rodway, although illiterate (she had to make a “X” to sign the marriage license), was smart enough to accept the relatively wealthy Carrington’s offer, neglecting to mention that she was already married to a man who she claimed was her brother. Although Ms. Rodway frequently visited her “brother” and supported him with Carrington’s money, the setup came to a bad end; Ms. Rodway, now Ms. Carrington, eventually attempted to break off the arrangement whereupon her “brother” showed up and tried to stab her to death with a switchblade. She recovered and Carrington was forgiving, but apparently the aftermath was too much for both of them and they both died from chloral hydrate overdoses (author Stuart Clark calls this “chloral of hydrate” throughout, which makes no sense as chemical nomenclature).

The remainder of the solar astronomers discussed had rather less interesting lives. William and John Herschel, Heinrich Schwabe, Edward Maunder (who also married, but more happily, a much younger woman, Annie Russell, the first woman worker at the Greenwich Observatory), and George Ellery Hale are the major players and there are a host of minor ones. The science is well explained, with Clark emphasizing mistakes as well as progress; too many science histories make it seem like each new theory was immediately accepted while Clark shows that Kuhnian-style paradigm shifts were more likely.

The “villains” are also Kuhnian; two of the most prominent scientists of the era (George Airy and Lord Kelvin) dismissed the idea that the sun had any effect on the Earth’s magnetic field. Clark quotes Kelvin’s famous maxim that “if you can’t measure it you don’t know what you’re talking about”, but Kelvin proved (as he had previously done with Darwin) that you can measure something just fine and still not know what you’re talking about. In both cases, Kelvin made critical false assumptions; for Darwin, that the only source of solar energy was gravitational contraction, and that therefore the age of the Earth was much too short for organic evolution; and for Maunder, that the entire sun would need to be involved in observed magnetic “storms” and that the amount of energy necessary would be unreasonably large. Kelvin’s authority was such that Maunder, despite reams of statistics showing correlation between sunspots and magnetic storms on Earth, couldn’t overcome it.

Airy’s role was also negative although more benign. Like Kelvin, he had made a number of important contributions to science but, also like Kelvin, his authority as a scientist outlasted his ability. He was Astronomer Royal for 46 years, and it seems that his particular goal in the position was maintaining the Greenwich Observatory’s role as a purveyor of accurate star and planetary measurements rather promoting more theoretical research. He seems to have disliked both Carrington and Maunder – Carrington because he was “in trade” (he owned a brewery) and Maunder because he had never received a university degree but was appointed to Greenwich as the result of a competitive examination. In Carrington’s case, Airy apparently worked behind the scenes to ensure Carrington didn’t get the observatory appointment he wanted (Carrington wanted to sell his brewery and devote himself full time to astronomy, but couldn’t manage without at least a small salary). Airy’s influence on Maunder was less direct, but Maunder was reportedly terrified of him; he once dropped a bottle of photographic chemicals from the shock of turning around and finding Airy, in full Victorian frock coat regalia, had been standing behind him watching him work.

The illustrations are all contemporary; a drawing of exactly how a coronal mass ejection works would have been helpful. The index is sparse, and there are a lot of Web references in the bibliography (to be fair, many of them are to electronic versions of published papers). There are a couple of puzzling scientific lapses – the “chloral of hydrate” mentioned above, and the claim that William Herschel minimized the heat generated during solar observations by using a telescope with an unpolished mirror. Clark, who is the editor of a British popular astronomy magazine, has to know that won’t work; an unpolished mirror will not produce a sharp image. There’s a hint of what he might mean; silvering or aluminizing glass hadn’t been invented yet, so Herschel’s mirrors were made of speculum metal. Speculum metal tarnishes in air, so the mirrors had to be frequently repolished to remove the tarnish. I suspect this is what Clark means; Herschel then may have initially polished and figured his solar telescope mirror but then allowed it to tarnish to reduce the reflectivity. Oddly, a major contribution of John Herschel to solar observing, the Herschel wedge, isn’t mentioned.

It’s a fast and easy read, though, and there are more than enough interesting little facts about the history of sunspot and magnetic astronomy to make up for the minor flaws.… (mais)