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Einstein's Clocks and Poincare's Maps: Empires of Time
"More than a history of science; it is a tour de force in the genre."-New York Times Book ReviewA dramatic new account of the parallel quests to harness time that culminated in the revolutionary science of relativity, Einstein's Clocks, Poincare's Maps is "part history, part science, part adventure, part biography, part meditation on the meaning of modernity....In Galison's telling of science, the meters and wires and epoxy and solder come alive as characters, along with physicists, engineers, technicians and others....Galison has unearthed fascinating material" (New York Times). Clocks and trains, telegraphs and colonial conquest: the challenges of the late nineteenth century were an indispensable real-world background to the enormous theoretical breakthrough of relativity. And two giants at the foundations of modern science were converging, step-by-step, on the answer: Albert Einstein, an young, obscure German physicist experimenting with measuring time using telegraph networks and with the coordination of clocks at train stations; and the renowned mathematician Henri Poincare, president of the French Bureau of Longitude, mapping time coordinates across continents. Each found that to understand the newly global world, he had to determine whether there existed a pure time in which simultaneity was absolute or whether time was relative. Esteemed historian of science Peter Galison has culled new information from rarely seen photographs, forgotten patents, and unexplored archives to tell the fascinating story of two scientists whose concrete, professional preoccupations engaged them in a silent race toward a theory that would conquer the empire of time.
393 pages, Kindle Edition
First published August 17, 2003
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November 10, 2015
This book is wrapped around one basic insight, heavily illustrated with anecdotes, stories, and biographical sketches. The insight is this: the theory of Special Relativity owes a great deal to the practical technical challenges of turn-of-the-century Europe. This claim is then elaborated through a close examination of the professional biographies of Poincare and Einstein, who both formulated versions of the same theory at virtually the same time.
One of the striking aspects of relativity (both according to Einstein and Poincare) is that it defines simultaneity as "the thing you get when you have clocks synchronized with propagation-delayed light pulses." This may seem like an odd thing to build into the theory -- it certainly struck me as odd when I first encountered it. Galison's contribution in this book is to put that definition into the context of the technology of the 1900s. A point I hadn't appreciated until I read the book is that wide-area clock synchronization were a relatively new development in 1905 -- time zones as we know them were only established a few decades earlier, and as late as 1912, France used Paris solar time, offset by 9:21 minutes from Greenwich.
There are two corollaries to this novelty, both of which are elaborated by Galison. The standard technique for measuring longitude differences in the late 19th century was to synchronize clocks by telegraph, and then measure local solar time in each location. For long-distance measurements, the propagation time of the electrical pulses (on the order of tens of milliseconds) was well within the available precision of contemporary instruments. "Synchronize clocks by sending light pulses and correcting for transit time" wasn't some goofy thought-experiment -- it was the actual way clocks were synchronized in 1905. Furthermore, this is something Henri Poincare would have known very well, since he was president of the Bureau of Longitude and responsible for overseeing a huge program of long-distance clock synchronization.
Now the second corollary: in 1905, railroads and municipal governments had a huge number of clocks and wanted them all kept synchronized automatically. This meant that there was a steady stream of electrical gadgets being patented for clock synchronization -- especially in Switzerland, where clockmaking was a major national industry. And many of these patents would have landed on the desk of patent clerk A. Einstein, specially associated with patents on electrotechnical apparatuses. Like Poincare, Einstein would have been extremely aware of how clock synchronization worked in practice. When Einstein wrote about how to synchronize a dispersed set of synchronized clocks via timing pulses, he wasn't doing a thought experiment at all, he was describing the state of the art in actual timekeeping technology.
Why does any of this matter? Partly, it's interesting simply as a historical excursion through an interesting and under-explored corner of technology. Partly, it's nice to know what Poincare and Einstein had in mind when they were formulating relativity. And finally, it strikes me as useful for better understanding the theory of relativity.
The relativistic definition of simultaneity seems strange if presented as a thought-experiment without context. It makes much more sense in a context of "this is how engineers synchronize clocks, which is a real and important problem for a whole bunch of practical reasons." Those textbook sketches of reference frames, with clocks and meter-sticks correspond to actual artifacts: 19th-century geographers were literally creating networks of synchronized clocks, coordinated by timing pulses. And the theory of special relativity has a lot more cohesion and intellectual force when you see it presented against this socio-technical context.
One of the striking aspects of relativity (both according to Einstein and Poincare) is that it defines simultaneity as "the thing you get when you have clocks synchronized with propagation-delayed light pulses." This may seem like an odd thing to build into the theory -- it certainly struck me as odd when I first encountered it. Galison's contribution in this book is to put that definition into the context of the technology of the 1900s. A point I hadn't appreciated until I read the book is that wide-area clock synchronization were a relatively new development in 1905 -- time zones as we know them were only established a few decades earlier, and as late as 1912, France used Paris solar time, offset by 9:21 minutes from Greenwich.
There are two corollaries to this novelty, both of which are elaborated by Galison. The standard technique for measuring longitude differences in the late 19th century was to synchronize clocks by telegraph, and then measure local solar time in each location. For long-distance measurements, the propagation time of the electrical pulses (on the order of tens of milliseconds) was well within the available precision of contemporary instruments. "Synchronize clocks by sending light pulses and correcting for transit time" wasn't some goofy thought-experiment -- it was the actual way clocks were synchronized in 1905. Furthermore, this is something Henri Poincare would have known very well, since he was president of the Bureau of Longitude and responsible for overseeing a huge program of long-distance clock synchronization.
Now the second corollary: in 1905, railroads and municipal governments had a huge number of clocks and wanted them all kept synchronized automatically. This meant that there was a steady stream of electrical gadgets being patented for clock synchronization -- especially in Switzerland, where clockmaking was a major national industry. And many of these patents would have landed on the desk of patent clerk A. Einstein, specially associated with patents on electrotechnical apparatuses. Like Poincare, Einstein would have been extremely aware of how clock synchronization worked in practice. When Einstein wrote about how to synchronize a dispersed set of synchronized clocks via timing pulses, he wasn't doing a thought experiment at all, he was describing the state of the art in actual timekeeping technology.
Why does any of this matter? Partly, it's interesting simply as a historical excursion through an interesting and under-explored corner of technology. Partly, it's nice to know what Poincare and Einstein had in mind when they were formulating relativity. And finally, it strikes me as useful for better understanding the theory of relativity.
The relativistic definition of simultaneity seems strange if presented as a thought-experiment without context. It makes much more sense in a context of "this is how engineers synchronize clocks, which is a real and important problem for a whole bunch of practical reasons." Those textbook sketches of reference frames, with clocks and meter-sticks correspond to actual artifacts: 19th-century geographers were literally creating networks of synchronized clocks, coordinated by timing pulses. And the theory of special relativity has a lot more cohesion and intellectual force when you see it presented against this socio-technical context.
June 7, 2017
A revealing picture of why the young seem to come out with the great new ideas. Contrasting a young Einstein to an established Poincare, Galison shows how the accumulated knowledge of the latter kept him from appreciating the full significance of special relativity as envisioned by the unencumbered Einstein. We see that the nascent ideas that would form the concept of special relativity were all around. Poincare embraced many of these new thoughts but kept trying to tie them into the accepted dogma of the ether. Einstein had no need of old ideas that couldn’t be observed, so was free to create brand new explanations of phenomena, in this case, the nature of time and ultimately space-time.
Some of the book is rather dry reading, recounting the late 19th century drive for standardization and synchronizing clocks. Although it is interesting to realize that our space based GPS system is simply the culmination of this effort to precisely set location and aid navigation. More importantly this background is key to understanding how Einstein and Poincare developed their science and why one made a critical breakthrough while the other was hamstrung by old ideas. It made me wonder about physics research today with so much focus on trying to find particles to complete the existing standard model, for example, one that would explain dark energy. Somehow the search just seems like Poincare trying to fit relativity into the ether. Even though the concept of ether had no experimental support and the standard model has much, it is still a model and will undoubtedly be replaced in time by a better one, probably with ideas from someone young who is not trying to fit the new into the old.
Galison also does a nice job of showing how three different areas of study converged in the formation of the theory of special relativity: Physics, philosophy and engineering. All three were changed forever as Einstein’s discoveries helped spawn a wholesale change in attitude towards inquiry and development in these disciplines that would clearly distinguish the twentieth century from the nineteenth. If you can put up with a little tedium as Galison digs into the international conventions to determine the meter, the prime meridian and time zones you will be well rewarded by this book. You will have a feel for the world of science, philosophy and technology that gave us Einstein and his great discoveries that in turn would lead to quantum mechanics and modern physics. Highly recommended.
Some of the book is rather dry reading, recounting the late 19th century drive for standardization and synchronizing clocks. Although it is interesting to realize that our space based GPS system is simply the culmination of this effort to precisely set location and aid navigation. More importantly this background is key to understanding how Einstein and Poincare developed their science and why one made a critical breakthrough while the other was hamstrung by old ideas. It made me wonder about physics research today with so much focus on trying to find particles to complete the existing standard model, for example, one that would explain dark energy. Somehow the search just seems like Poincare trying to fit relativity into the ether. Even though the concept of ether had no experimental support and the standard model has much, it is still a model and will undoubtedly be replaced in time by a better one, probably with ideas from someone young who is not trying to fit the new into the old.
Galison also does a nice job of showing how three different areas of study converged in the formation of the theory of special relativity: Physics, philosophy and engineering. All three were changed forever as Einstein’s discoveries helped spawn a wholesale change in attitude towards inquiry and development in these disciplines that would clearly distinguish the twentieth century from the nineteenth. If you can put up with a little tedium as Galison digs into the international conventions to determine the meter, the prime meridian and time zones you will be well rewarded by this book. You will have a feel for the world of science, philosophy and technology that gave us Einstein and his great discoveries that in turn would lead to quantum mechanics and modern physics. Highly recommended.
February 22, 2018
Exemplary in terms of the detail and the focus the book has on the establishment of time synchronisation and the question of simultaneity that plagued the brilliant minds of Poincare, Einstein and many others in late nineteenth and early twentieth century. Through the exploration of the meaning of time, be it in a philosophical, scientific or purely technical manner, the author hammers home the many intricacies, methodologies and even competing views of what science actually is or should be, that existed at the the turn of the century. The book rightfully focuses more on Poincare than Einstein and contrasts their approaches and thinking beautifully. Einstein the ‘rebel’ is given due regard and space for his contributions to this intricate field, but personally, I fell in love with the image of Henri Poincare that is presented here: his longing to preserve old ideas through modification so we do not disregard the work of the titans of the past entirely. Also, this is the first time I have come to learn of the methods of map-making and the techniques used to establish longitudes. All in all, this is a brilliant book which, even though it may get a little dry at times, provides a fascinating picture of a typically obscure field of study through the work of the two most imporatant characters in its history.
October 10, 2017
This book presents ideas on simultaneity and what kind of importance it had/has in physics, philosophy and everyday life.
It was interesting to read about time standardization and how Poincaré tried to get to time decimalization.
It was interesting to read about time standardization and how Poincaré tried to get to time decimalization.
March 21, 2019
Galison, Peter (2003). Einstein’s Clocks, Poincare’s Maps: Empires of Time. New York: W. W. Norton. ISBN: 9780393243864. Pagine 400. 10,76 €.
Forse perché non ho mai amato particolarmente la fisica, negletta nel mio sconfinato amore per le scienze, ho fatto fatica, soprattutto all’inizio.
Naturalmente sapevo chi è Einstein anche prima di leggere questo libro: ho anche letto a suo tempo la sua esposizione divulgativa La relatività nella brutta edizione Newton Compton (a mia discolpa: ero un liceale squattrinato) e mi sembrava addirittura di averla compresa. Di Poincaré avevo una conoscenza che dire vaga è poco: francese, certo; ottocentesco (e qui già mi sbagliavo almano un po’, perché era vivo quando Einstein aveva pubblicato il suo famoso articolo del 1905 e aveva fatto in tempo a discuterne); ma quale contributo aveva dato alla matematica e alla fisica? Non facile, la risposta a quest’ultima domanda, perché Poincaré era uomo dal multiforme ingegno e, tra l’altro, benissimo introdotto anche nelle vicende di “politica della scienza” e politica tout court che riguardavano il suo paese, la Francia.
Insomma, certamente per i miei limiti, ma forse anche per il modo in cui Galison affronta il suo tema, all’inizio non capivo bene dove l’autore volesse andare a parare. È vero che nel capitolo iniziale – intitolato Synchrony – si afferma:
This book is about that clock-coordinating procedure. Simple as it seems, our subject, the coordination of clocks, is at once lofty abstraction and industrial concreteness. (p. 13)
Questa affermazione, per quanto netta, a me ha confuso piuttosto che orientare. Anche perché i capitoli successivi procedono secondo una logica che diventa chiara soltanto al procedere della lettura.
Siamo abituati, nella vita quotidiana di oggi, a dare per scontata la misurazione del tempo. Ho abbastanza anni per ricordare che l’orologio della prima comunione era un (elegantissimo e piatto) orologio meccanico: un capolavoro di ingegneria miniaturizzata. Ma ricordo che mi dissero che era un buon orologio, perché “perdeva” (o “guadagnava”, non ricordo) un minuto ogni due o tre giorni. Sul quadrante c’era scritto qualche cosa come “15 rubini”, e mio padre mi aveva spiegato che si trattava di veri rubini, ancorché minuscoli, con la funzione di perni per minimizzare l’attrito e migliorare la precisione meccanica.
Qualche anno dopo arrivò il Bulova Accutron: ce l’avevano alcuni miei compagni (ricchi) delle medie. L’Accutron sostituiva il bilanciere con un diapason, con due vantaggi che concorrevano a diminuire le fonti d’errore meccanico: spariva il movimento meccanico oscillatorio del bilanciere (un elemento di errore meccanico in meno), e la frequenza della vibrazione che governava le lancette era molto più elevata (360 Hz invece di 5-10). 360 Hz è una frequenza udibile: se consideriamo l’accordatura standard, in cui il la centrale (la4) è accordato a 440 Hz, stiamo parlando di una nota di poco sotto al fa#4. Insomma, se ti addormentavi con un Accutron al polso sotto l’orecchio, ti svegliavi un po’ rintronato – almeno così dicevamo dei fortunati compagni di scuola che ce l’avevano (questo non mi impedisce di averne sempre desiderato uno, e di desiderarlo ancora adesso). Naturalmente, era anche il primo orologio elettronico: serviva una batteria, che durava circa un anno, per far vibrare il diapason. Diapason e bobine erano visibili sul quadrante. Era un gioiello d’ingegneria, molto più preciso anche dei migliori cronografi meccanici: circa un minuto al mese.
Qualche anno dopo – ma andavo ancora al liceo – lessi che un cristallo di quarzo, grazie alle sue caratteristiche piezolettriche (sottoposto a compressione meccanica produce una differenza di potenziale; e viceversa, sottoposto a tensione elettrica si deforma meccnicamente), avrebbe sostituito il diapason, vibrando a una frequenza molto maggiore (tipicamente, 32.768 Hz, circa 100 volte più del diapason dell’Accutron e inudibile all’orecchio umano) e raggiungendo una precisione molto più elavata (assoluta, diceva l’articolo, esagerando). Ne ero affascinato. Poco prima di natale del 1969 (pochi mesi dopo lo sbarco di Armstrong sulla luna) una casa giapponese a me sconosciuta, la Seiko, lanciò il
di modello 35 SQ Astron: vantava una precisione di 5 secondi al mese e costava una fortuna (450.000 yen, pari a 1.250 dollari dell’epoca: come una Toyota Corolla di allora, secondo Wikipedia). Era un orologio panciuto, molto più dei cronografi svizzeri, e funzionava male: dopo 100 esemplari, la Seiko smise di produrlo.
Ma in pochi anni arrivano gli orologi al quarzo (in realtà adesso si usa la ceramica) con cassa di plastica e display digitale (a LED prima, e a cristalli liquidi poi): nel 1975, la Texas Instruments ne vendeva uno a 20 dollari. Furono accolti con incredibile entusiasmo, e non solo da me. Per un po’ si pensò che avrebbero condannato all’estinzione gli orologi analogici e al fallimento le prestigiose case svizzere. Nulla di tutto questo, anche se i ragazzi oggi non sanno più leggere il quadrante tradizionale e, se è per quello, non usano più l’orologoio ma leggono l’ora sul cellulare. Douglas Adams prende in giro questa mania in una pagina famosa di The Hitchhiker’s Guide to the Galaxy.
Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-eight million miles is an utterly insignificant little blue-green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea. […]
This planet has – or rather had – a problem, which was this: most of the people living on it were unhappy for pretty much of the time. Many solutions were suggested for this problem, but most of these were largely concerned with the movement of small green pieces of paper, which was odd because on the whole it wasn’t the small green pieces of paper that were unhappy.
And so the problem remained; lots of people were mean, and most of them were miserable, even the ones with digital watches.
Ho divagato, tanto per cambiare. Quello su cui volevo attirare l’attenzione è che diamo ormai per scontata la misurazione del tempo e la sincronia. Da questo dipendono un sacco di altre cose che diamo per scontate: dal navigatore GPS al web, allo stesso telefono. Ma questo è un fenomeno relativamente moderno.
Misurare il tempo localmente è la cosa più semplice del mondo. Quando il sole raggiunge il punto più alto della sua traiettoria apparente, quello è mezzogiorno, in quel posto (un gioco che si può fare ancora adesso, e che i miei figli ricorderanno, è quello di piantare un bastone in verticale e segnare il percorso dell’ombra: quando è al suo minimo, è il mezzogiorno locale, anche se l’orologio segna, metti, le 13:22). Se in un altro posto il mezzogiorno locale è alla stessa ora, si dice che sono sullo stesso meridiano (che si chiama appunto così perché è il luogo dei punti in cui il mezzogiorno è contemporaneo). Ma se l’ora locale in un altro posto è diversa, posso calcolare la differenza tra le longitudini dei due posti, basandomi sul fatto che la traiettoria apparente del sole ci mette 24 ore a tornare al punto di partenza. Se la differenza è (supponiamo) di 3 ore, i due posti hanno una differenza di longitudine di 45°. Ma come faccio a sapere che ora è in un altro posto, distante dal mio? È il tema di un altro bel libro – Longitude di Dava Sobel – che ho letto qualche anno fa: se andate all’osservatorio di Greenwich potete ammirare gli orologi realizzati da John Harrison per risolvere il problema di determinare la longitudine delle navi in mare, e in particolare il modello “tascabile”, di soli 12 cm, costruito con matriali in grado di risolvere i problemi dell’ossidazione e dei movimenti dell’imbarcazione, diventati famosi anche per i non addetti ai lavori proprio grazie a quel libro. L’idea di Harrison era che se regolo l’orologio, alla partenza, sull’ora di Liverpool e lo mantengo preciso, quando sono in mare posso calcaolare il mezzogiorno locale con la strumentazione ottica di bordo e tradurre lo scarto tra mezzogiorno locale e ora di Liverpool in gradi di longitudine.
Va bene, direte voi: dato che la realizzazione di Harrison è del 1753, che problema ci poteva essere nella seconda metà dell’Ottocento? Tanto per comiciare, gli orologi, nonostante i perfezionamenti, non erano abbastanza precisi. E le misurazioni a bordo, su una tolda che rulla e beccheggia, erano tutt’altro che agevoli. Galison cita, per tutti, il tentativo fatto nell’estate del 1849 per misurare la distanza tra Liverpool e Cambridge nel Massachussets: sette viaggi nei due versi, ognuno con 12 cronometri a bordo. Di nuovo nel 1851, sette viaggi in un verso e due nell’altro, 37 cronometri, 93 misurazioni: niente da fare. Con i tentativi di misurazione astronomica, una strategia iniziata ancora prima di Harrison, non andò meglio.
Al problema tecnico se ne aggiungeva uno pratico: con i mezzi di comunicazione dell’epoca, era ritenuto più importante conoscere l’effettivo mezzogiorno locale che sincronizzarsi su un’ora regionale o nazionale.
Ma poi arrivano i treni. All’inizio il problema della sincronizzazione non si pone: comanda il tempo della stazione principale. Quello di Parigi per la linea Parigi-Brest, quello di New York per la New York-Hartford. Nelle stazioni si avevano almeno due ore diverse (quella locale e quello del terminale della linea). Al moltiplicarsi delle linee si moltiplicano i problemi.
E poi arriva il telegrafo: ma con il nuovo problema arriva una speranza di soluzione: si possono sincronizzare le ore trasmettendo un segnale tra due luoghi? Forse, ma emergono due ostacoli di diversa natura.
Il primo è geopolitico; chi detta le regole? I francesi accampavano un diritto di primogenitura: nel 1791, in piena rivoluzione, l’Accademia francese delle scienze aveva definito il metro come 1/10.000.000 della distanza tra polo ed equatore misurata sul meridiano di Parigi; nel 1795 la Francia l’aveva adottato ufficialmente come misura di lunghezza e le armate napoleoniche l’avevano diffuso in punta di baionetta (non resisto a questa bella espressione). Il 20 maggio 1875 a Parigi (Poincaré c’era) 17 paesi avevano solennemente firmato la Convensione del metro e istituito l’Ufficio internazionale dei pesi e delle misure con sede a Sévres, vicino a Parigi. Ovvio che volessero anche che il meridiano 0 fosse quello di Parigi. Misero in piedi una serie di spedizioni geografico-telegrafiche per misurare le distanze da Parigi basandosi sull’ora locale, quella di Parigi e la (supposta) istantaneità della trasmissione. Ma i cavi sottomarini erano per lo più britannici, e la Francia perse alla fine la battaglia con Greenwich.
Il secondo è tecnologico e scientifico. Se è vero che per le linee aeree la velocità di propagazione dell’onda elettromagnetica è quella della luce, “per le linee in cavo la velocità è inferiore in quanto aumenta la costante dielettrica del materiale. […] Ad esempio se la costante dielettrica relativa è 4, la velocità di propagazione diventa la metà: 150.000 km/s.” (cfr. Velocità della corrente). Quindi, la sperata simultaneità non c’è. Il tempo, alla fine, è una questione di convenzione, di convenienza. Questa è la conclusione di Poincaré e, al fondo, anche quella di Einstein, anche se i due non si compresero mai fino in fondo.
Il libro è molto più ricco del mio racconto. Ma l’ho fatta fin troppo lunga, e lascio parlare le citazioni dal testo.
To Willard Van Orman Quine, one of the most influential American philosophers of the twentieth century, all knowledge was ultimately revisable […] (p. 25)
Poincaré emphasized that there are free choices in representing the world, choices fixed not by something completely exterior, but rather fixed by the simplicity and convenience of our knowledge. (p. 77)
In a curt, insistent sentence printed in 1891, he lay down a new formulation of his view of geometric axioms: “They are conventions.” “Is Euclidean geometry true? It has no meaning. We might as well ask if the metric system is true, and if the old weights and measures are false; if Cartesian co-ordinates are true and polar co-ordinates false. One geometry cannot be more true than another; it can only be more convenient. Now, Euclidean geometry is, and will remain, the most convenient.” (p. 82)
Joseph Conrad’s version of the events in his 1907 work The Secret Agent remains the canvas on which these events have been seen: a dark sketch of dupes, manipulators, and careerists from which no one emerges unsullied. In Conrad’s world the conniving First Secretary of a Foreign Power insisted on an attack that would frighten the class enemies beyond murder: “The demonstration must be against learning—science. The attack must have all the shocking senselessness of gratuitous blasphemy.” It must strike at the mysterious scientific heart of material prosperity. “‘Yes,’ he continued with a contemptuous smile. ‘The blowing up of the first meridian is bound to raise a howl of execration.’” (p. 159)
Convenience, convention, continuity with the past. (p. 165: termini ricorrenti negli scritti di Poincaré)
Cornu insisted that it was the day, the natural unit of time, that should be decimalized—not the wholly artificial hour. If the day were the base, then a hundredth of the day would be just about a quarter of an hour, and a hundred-thousandth of a day would equal 0.86 old-style seconds. That would be a gratifying unit of time because it corresponded so closely to the typical adult heartbeat, our “natural” small temporal unit. (p. 170)
“In reality, measurable duration is a variable, chosen from among all the variables present in the study of movements, because it lends itself particularly well to the expression of simple laws of movement.” (p. 189: la citazione è di Calinon)
We choose these rules, Poincaré insisted in oft-cited words, not because they are true, but because they are convenient. (p. 190)
Objective reality was nothing other than the commonly held relationships among the phenomena of the world. There was no otherworldly plane of existence for Poincaré. The importance of scientific knowledge lay in the persistence of particular true relations, not in a back-of-the-curtain reality of Platonic forms or ungraspable noumena. (p. 212)
[…] confusing conception and perception […] (p. 238: la citazione è di Karl Pearson)
Einstein began to forge an approach to physics that emphasized principles and eschewed detailed model building. (p. 239)
Einstein: The principle is logically not necessary: it would be necessary only if it would be made such by experience. But it is made only probable by experience. (p. 268)
For Poincaré, too, principles were made probable by experience, but principles were precisely what was expedient; they could be held against the grain of experience only at the cost of immense inconvenience. (p. 268)
For Einstein, principles were more than definitions, they were pillars, supports of the structure of knowledge. And this despite the circumstance that our knowledge of principles could never be certain; our hold on them was necessarily provisional, only probable, never forced by logic or experience. (p. 268)
For all these purposes relativistic time coordination was deep in the machine. According to relativity, satellites that were orbiting the earth at 12,500 miles per hour ran their clocks slow (relative to the earth) by 7 millionths of a second per day. Even general relativity (Einstein’s theory of gravity) had to be programmed into the system. Eleven thousand miles in space, where the satellites orbited, general relativity predicted that the weaker gravitational field would leave the satellite clocks running fast (relative to the earth’s surface) by 45 millionths of a second per day. Together, these two corrections add up to a staggering correction of 38 millionths (that is, 38,000 billionths) of a second per day in a GPS system that had to be accurate to within 50 billionths of a second each day. (p. 288)
[Poincaré] was fascinated by Kant’s emphasis on structures through which experience becomes possible […] (p. 316)
True relations, not truth by itself. Visible surfaces, not obscure depths. (p. 316)
Like Poincaré, Einstein believed that laws must be simple, not for our convenience but because (as Einstein put it) “nature is the realization of the simplest conceivable mathematical ideas.” The form of the theory therefore had to exhibit in its detailed form the reality of the phenomena: “In a certain sense,” Einstein later insisted, “I hold it true that pure thought can grasp reality, as the ancients dreamed.”19 Einstein believed that a proper theory would match the phenomena in austerity. In that depth lay a contemplative theology. Not the religiosity of a personal, vengeful, or judgmental God, but a mostly hidden God of an underlying natural order: “The scientist is possessed by the sense of universal causation. The future to him is every whit as necessary and determined as the past. . . . His religious feeling takes the form of a rapturous amazement at the harmony of natural law which reveals an intelligence of such superiority.” Sometimes it was given to the physicist to advance by the provisional application of heuristic devices; these could tide the theory over until further development was possible. Such a provisional use of formal principles played a role in thermodynamics, in quantum theory, and in relativity. But Einstein insisted over and over that, insofar as they could, scientists fashioned theories that seized some bit of the underlying, simple, and harmonious natural order. Since Einstein believed that the phenomena did not distinguish true from apparent time, neither, he insisted, should the theory. (p. 318)
To find a more recent mixture of abstraction and concreteness of this kind, we can look to the mid-twentieth-century explosion of “information sciences”: cybernetics, computer science, cognitive science. (p. 321)
Distributed, coordinated precision time was more than money for Favarger, it was each person’s access to orderliness, interior and exterior—to freedom from time anarchy. (p. 323)
On the flip side was the antipositivist movement popular in the 1960s and 1970s. Thoughts structured things. Antipositivists aimed to reverse the older generation’s epistemic order; they saw programmes, paradigms, and conceptual schemes as coming first, and they held these to have completely reshaped experiments and instruments. (p. 324)
We find metaphysics in machines, and machines in metaphysics. Modernity, just in time. (p. 328)
Forse perché non ho mai amato particolarmente la fisica, negletta nel mio sconfinato amore per le scienze, ho fatto fatica, soprattutto all’inizio.
Naturalmente sapevo chi è Einstein anche prima di leggere questo libro: ho anche letto a suo tempo la sua esposizione divulgativa La relatività nella brutta edizione Newton Compton (a mia discolpa: ero un liceale squattrinato) e mi sembrava addirittura di averla compresa. Di Poincaré avevo una conoscenza che dire vaga è poco: francese, certo; ottocentesco (e qui già mi sbagliavo almano un po’, perché era vivo quando Einstein aveva pubblicato il suo famoso articolo del 1905 e aveva fatto in tempo a discuterne); ma quale contributo aveva dato alla matematica e alla fisica? Non facile, la risposta a quest’ultima domanda, perché Poincaré era uomo dal multiforme ingegno e, tra l’altro, benissimo introdotto anche nelle vicende di “politica della scienza” e politica tout court che riguardavano il suo paese, la Francia.
Insomma, certamente per i miei limiti, ma forse anche per il modo in cui Galison affronta il suo tema, all’inizio non capivo bene dove l’autore volesse andare a parare. È vero che nel capitolo iniziale – intitolato Synchrony – si afferma:
This book is about that clock-coordinating procedure. Simple as it seems, our subject, the coordination of clocks, is at once lofty abstraction and industrial concreteness. (p. 13)
Questa affermazione, per quanto netta, a me ha confuso piuttosto che orientare. Anche perché i capitoli successivi procedono secondo una logica che diventa chiara soltanto al procedere della lettura.
Siamo abituati, nella vita quotidiana di oggi, a dare per scontata la misurazione del tempo. Ho abbastanza anni per ricordare che l’orologio della prima comunione era un (elegantissimo e piatto) orologio meccanico: un capolavoro di ingegneria miniaturizzata. Ma ricordo che mi dissero che era un buon orologio, perché “perdeva” (o “guadagnava”, non ricordo) un minuto ogni due o tre giorni. Sul quadrante c’era scritto qualche cosa come “15 rubini”, e mio padre mi aveva spiegato che si trattava di veri rubini, ancorché minuscoli, con la funzione di perni per minimizzare l’attrito e migliorare la precisione meccanica.
Qualche anno dopo arrivò il Bulova Accutron: ce l’avevano alcuni miei compagni (ricchi) delle medie. L’Accutron sostituiva il bilanciere con un diapason, con due vantaggi che concorrevano a diminuire le fonti d’errore meccanico: spariva il movimento meccanico oscillatorio del bilanciere (un elemento di errore meccanico in meno), e la frequenza della vibrazione che governava le lancette era molto più elevata (360 Hz invece di 5-10). 360 Hz è una frequenza udibile: se consideriamo l’accordatura standard, in cui il la centrale (la4) è accordato a 440 Hz, stiamo parlando di una nota di poco sotto al fa#4. Insomma, se ti addormentavi con un Accutron al polso sotto l’orecchio, ti svegliavi un po’ rintronato – almeno così dicevamo dei fortunati compagni di scuola che ce l’avevano (questo non mi impedisce di averne sempre desiderato uno, e di desiderarlo ancora adesso). Naturalmente, era anche il primo orologio elettronico: serviva una batteria, che durava circa un anno, per far vibrare il diapason. Diapason e bobine erano visibili sul quadrante. Era un gioiello d’ingegneria, molto più preciso anche dei migliori cronografi meccanici: circa un minuto al mese.
Qualche anno dopo – ma andavo ancora al liceo – lessi che un cristallo di quarzo, grazie alle sue caratteristiche piezolettriche (sottoposto a compressione meccanica produce una differenza di potenziale; e viceversa, sottoposto a tensione elettrica si deforma meccnicamente), avrebbe sostituito il diapason, vibrando a una frequenza molto maggiore (tipicamente, 32.768 Hz, circa 100 volte più del diapason dell’Accutron e inudibile all’orecchio umano) e raggiungendo una precisione molto più elavata (assoluta, diceva l’articolo, esagerando). Ne ero affascinato. Poco prima di natale del 1969 (pochi mesi dopo lo sbarco di Armstrong sulla luna) una casa giapponese a me sconosciuta, la Seiko, lanciò il
di modello 35 SQ Astron: vantava una precisione di 5 secondi al mese e costava una fortuna (450.000 yen, pari a 1.250 dollari dell’epoca: come una Toyota Corolla di allora, secondo Wikipedia). Era un orologio panciuto, molto più dei cronografi svizzeri, e funzionava male: dopo 100 esemplari, la Seiko smise di produrlo.
Ma in pochi anni arrivano gli orologi al quarzo (in realtà adesso si usa la ceramica) con cassa di plastica e display digitale (a LED prima, e a cristalli liquidi poi): nel 1975, la Texas Instruments ne vendeva uno a 20 dollari. Furono accolti con incredibile entusiasmo, e non solo da me. Per un po’ si pensò che avrebbero condannato all’estinzione gli orologi analogici e al fallimento le prestigiose case svizzere. Nulla di tutto questo, anche se i ragazzi oggi non sanno più leggere il quadrante tradizionale e, se è per quello, non usano più l’orologoio ma leggono l’ora sul cellulare. Douglas Adams prende in giro questa mania in una pagina famosa di The Hitchhiker’s Guide to the Galaxy.
Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-eight million miles is an utterly insignificant little blue-green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea. […]
This planet has – or rather had – a problem, which was this: most of the people living on it were unhappy for pretty much of the time. Many solutions were suggested for this problem, but most of these were largely concerned with the movement of small green pieces of paper, which was odd because on the whole it wasn’t the small green pieces of paper that were unhappy.
And so the problem remained; lots of people were mean, and most of them were miserable, even the ones with digital watches.
Ho divagato, tanto per cambiare. Quello su cui volevo attirare l’attenzione è che diamo ormai per scontata la misurazione del tempo e la sincronia. Da questo dipendono un sacco di altre cose che diamo per scontate: dal navigatore GPS al web, allo stesso telefono. Ma questo è un fenomeno relativamente moderno.
Misurare il tempo localmente è la cosa più semplice del mondo. Quando il sole raggiunge il punto più alto della sua traiettoria apparente, quello è mezzogiorno, in quel posto (un gioco che si può fare ancora adesso, e che i miei figli ricorderanno, è quello di piantare un bastone in verticale e segnare il percorso dell’ombra: quando è al suo minimo, è il mezzogiorno locale, anche se l’orologio segna, metti, le 13:22). Se in un altro posto il mezzogiorno locale è alla stessa ora, si dice che sono sullo stesso meridiano (che si chiama appunto così perché è il luogo dei punti in cui il mezzogiorno è contemporaneo). Ma se l’ora locale in un altro posto è diversa, posso calcolare la differenza tra le longitudini dei due posti, basandomi sul fatto che la traiettoria apparente del sole ci mette 24 ore a tornare al punto di partenza. Se la differenza è (supponiamo) di 3 ore, i due posti hanno una differenza di longitudine di 45°. Ma come faccio a sapere che ora è in un altro posto, distante dal mio? È il tema di un altro bel libro – Longitude di Dava Sobel – che ho letto qualche anno fa: se andate all’osservatorio di Greenwich potete ammirare gli orologi realizzati da John Harrison per risolvere il problema di determinare la longitudine delle navi in mare, e in particolare il modello “tascabile”, di soli 12 cm, costruito con matriali in grado di risolvere i problemi dell’ossidazione e dei movimenti dell’imbarcazione, diventati famosi anche per i non addetti ai lavori proprio grazie a quel libro. L’idea di Harrison era che se regolo l’orologio, alla partenza, sull’ora di Liverpool e lo mantengo preciso, quando sono in mare posso calcaolare il mezzogiorno locale con la strumentazione ottica di bordo e tradurre lo scarto tra mezzogiorno locale e ora di Liverpool in gradi di longitudine.
Va bene, direte voi: dato che la realizzazione di Harrison è del 1753, che problema ci poteva essere nella seconda metà dell’Ottocento? Tanto per comiciare, gli orologi, nonostante i perfezionamenti, non erano abbastanza precisi. E le misurazioni a bordo, su una tolda che rulla e beccheggia, erano tutt’altro che agevoli. Galison cita, per tutti, il tentativo fatto nell’estate del 1849 per misurare la distanza tra Liverpool e Cambridge nel Massachussets: sette viaggi nei due versi, ognuno con 12 cronometri a bordo. Di nuovo nel 1851, sette viaggi in un verso e due nell’altro, 37 cronometri, 93 misurazioni: niente da fare. Con i tentativi di misurazione astronomica, una strategia iniziata ancora prima di Harrison, non andò meglio.
Al problema tecnico se ne aggiungeva uno pratico: con i mezzi di comunicazione dell’epoca, era ritenuto più importante conoscere l’effettivo mezzogiorno locale che sincronizzarsi su un’ora regionale o nazionale.
Ma poi arrivano i treni. All’inizio il problema della sincronizzazione non si pone: comanda il tempo della stazione principale. Quello di Parigi per la linea Parigi-Brest, quello di New York per la New York-Hartford. Nelle stazioni si avevano almeno due ore diverse (quella locale e quello del terminale della linea). Al moltiplicarsi delle linee si moltiplicano i problemi.
E poi arriva il telegrafo: ma con il nuovo problema arriva una speranza di soluzione: si possono sincronizzare le ore trasmettendo un segnale tra due luoghi? Forse, ma emergono due ostacoli di diversa natura.
Il primo è geopolitico; chi detta le regole? I francesi accampavano un diritto di primogenitura: nel 1791, in piena rivoluzione, l’Accademia francese delle scienze aveva definito il metro come 1/10.000.000 della distanza tra polo ed equatore misurata sul meridiano di Parigi; nel 1795 la Francia l’aveva adottato ufficialmente come misura di lunghezza e le armate napoleoniche l’avevano diffuso in punta di baionetta (non resisto a questa bella espressione). Il 20 maggio 1875 a Parigi (Poincaré c’era) 17 paesi avevano solennemente firmato la Convensione del metro e istituito l’Ufficio internazionale dei pesi e delle misure con sede a Sévres, vicino a Parigi. Ovvio che volessero anche che il meridiano 0 fosse quello di Parigi. Misero in piedi una serie di spedizioni geografico-telegrafiche per misurare le distanze da Parigi basandosi sull’ora locale, quella di Parigi e la (supposta) istantaneità della trasmissione. Ma i cavi sottomarini erano per lo più britannici, e la Francia perse alla fine la battaglia con Greenwich.
Il secondo è tecnologico e scientifico. Se è vero che per le linee aeree la velocità di propagazione dell’onda elettromagnetica è quella della luce, “per le linee in cavo la velocità è inferiore in quanto aumenta la costante dielettrica del materiale. […] Ad esempio se la costante dielettrica relativa è 4, la velocità di propagazione diventa la metà: 150.000 km/s.” (cfr. Velocità della corrente). Quindi, la sperata simultaneità non c’è. Il tempo, alla fine, è una questione di convenzione, di convenienza. Questa è la conclusione di Poincaré e, al fondo, anche quella di Einstein, anche se i due non si compresero mai fino in fondo.
Il libro è molto più ricco del mio racconto. Ma l’ho fatta fin troppo lunga, e lascio parlare le citazioni dal testo.
To Willard Van Orman Quine, one of the most influential American philosophers of the twentieth century, all knowledge was ultimately revisable […] (p. 25)
Poincaré emphasized that there are free choices in representing the world, choices fixed not by something completely exterior, but rather fixed by the simplicity and convenience of our knowledge. (p. 77)
In a curt, insistent sentence printed in 1891, he lay down a new formulation of his view of geometric axioms: “They are conventions.” “Is Euclidean geometry true? It has no meaning. We might as well ask if the metric system is true, and if the old weights and measures are false; if Cartesian co-ordinates are true and polar co-ordinates false. One geometry cannot be more true than another; it can only be more convenient. Now, Euclidean geometry is, and will remain, the most convenient.” (p. 82)
Joseph Conrad’s version of the events in his 1907 work The Secret Agent remains the canvas on which these events have been seen: a dark sketch of dupes, manipulators, and careerists from which no one emerges unsullied. In Conrad’s world the conniving First Secretary of a Foreign Power insisted on an attack that would frighten the class enemies beyond murder: “The demonstration must be against learning—science. The attack must have all the shocking senselessness of gratuitous blasphemy.” It must strike at the mysterious scientific heart of material prosperity. “‘Yes,’ he continued with a contemptuous smile. ‘The blowing up of the first meridian is bound to raise a howl of execration.’” (p. 159)
Convenience, convention, continuity with the past. (p. 165: termini ricorrenti negli scritti di Poincaré)
Cornu insisted that it was the day, the natural unit of time, that should be decimalized—not the wholly artificial hour. If the day were the base, then a hundredth of the day would be just about a quarter of an hour, and a hundred-thousandth of a day would equal 0.86 old-style seconds. That would be a gratifying unit of time because it corresponded so closely to the typical adult heartbeat, our “natural” small temporal unit. (p. 170)
“In reality, measurable duration is a variable, chosen from among all the variables present in the study of movements, because it lends itself particularly well to the expression of simple laws of movement.” (p. 189: la citazione è di Calinon)
We choose these rules, Poincaré insisted in oft-cited words, not because they are true, but because they are convenient. (p. 190)
Objective reality was nothing other than the commonly held relationships among the phenomena of the world. There was no otherworldly plane of existence for Poincaré. The importance of scientific knowledge lay in the persistence of particular true relations, not in a back-of-the-curtain reality of Platonic forms or ungraspable noumena. (p. 212)
[…] confusing conception and perception […] (p. 238: la citazione è di Karl Pearson)
Einstein began to forge an approach to physics that emphasized principles and eschewed detailed model building. (p. 239)
Einstein: The principle is logically not necessary: it would be necessary only if it would be made such by experience. But it is made only probable by experience. (p. 268)
For Poincaré, too, principles were made probable by experience, but principles were precisely what was expedient; they could be held against the grain of experience only at the cost of immense inconvenience. (p. 268)
For Einstein, principles were more than definitions, they were pillars, supports of the structure of knowledge. And this despite the circumstance that our knowledge of principles could never be certain; our hold on them was necessarily provisional, only probable, never forced by logic or experience. (p. 268)
For all these purposes relativistic time coordination was deep in the machine. According to relativity, satellites that were orbiting the earth at 12,500 miles per hour ran their clocks slow (relative to the earth) by 7 millionths of a second per day. Even general relativity (Einstein’s theory of gravity) had to be programmed into the system. Eleven thousand miles in space, where the satellites orbited, general relativity predicted that the weaker gravitational field would leave the satellite clocks running fast (relative to the earth’s surface) by 45 millionths of a second per day. Together, these two corrections add up to a staggering correction of 38 millionths (that is, 38,000 billionths) of a second per day in a GPS system that had to be accurate to within 50 billionths of a second each day. (p. 288)
[Poincaré] was fascinated by Kant’s emphasis on structures through which experience becomes possible […] (p. 316)
True relations, not truth by itself. Visible surfaces, not obscure depths. (p. 316)
Like Poincaré, Einstein believed that laws must be simple, not for our convenience but because (as Einstein put it) “nature is the realization of the simplest conceivable mathematical ideas.” The form of the theory therefore had to exhibit in its detailed form the reality of the phenomena: “In a certain sense,” Einstein later insisted, “I hold it true that pure thought can grasp reality, as the ancients dreamed.”19 Einstein believed that a proper theory would match the phenomena in austerity. In that depth lay a contemplative theology. Not the religiosity of a personal, vengeful, or judgmental God, but a mostly hidden God of an underlying natural order: “The scientist is possessed by the sense of universal causation. The future to him is every whit as necessary and determined as the past. . . . His religious feeling takes the form of a rapturous amazement at the harmony of natural law which reveals an intelligence of such superiority.” Sometimes it was given to the physicist to advance by the provisional application of heuristic devices; these could tide the theory over until further development was possible. Such a provisional use of formal principles played a role in thermodynamics, in quantum theory, and in relativity. But Einstein insisted over and over that, insofar as they could, scientists fashioned theories that seized some bit of the underlying, simple, and harmonious natural order. Since Einstein believed that the phenomena did not distinguish true from apparent time, neither, he insisted, should the theory. (p. 318)
To find a more recent mixture of abstraction and concreteness of this kind, we can look to the mid-twentieth-century explosion of “information sciences”: cybernetics, computer science, cognitive science. (p. 321)
Distributed, coordinated precision time was more than money for Favarger, it was each person’s access to orderliness, interior and exterior—to freedom from time anarchy. (p. 323)
On the flip side was the antipositivist movement popular in the 1960s and 1970s. Thoughts structured things. Antipositivists aimed to reverse the older generation’s epistemic order; they saw programmes, paradigms, and conceptual schemes as coming first, and they held these to have completely reshaped experiments and instruments. (p. 324)
We find metaphysics in machines, and machines in metaphysics. Modernity, just in time. (p. 328)
November 24, 2024
Poincaré saw how conventionality as a definition could be so hypnotizing with its useful generalizations. Einstein focused on the idealistic definitions and variables he used to describe the universe, as a kind of best compromised fit of reality. He couldn’t completely tell the difference between the definitions and the actual reality.
Many philosophers and scientists like Poincaré could at least tell when there is no clear distinction between the tools of perception we use to observe phenomena and the phenomena itself. Definitions, variables, identities and representations have a way of territorializing time and projecting that onto space. A way of generalizing and compromising change, rather than observing each relative moment in its longer more impermanent context.
Einstein’s paradigm improved on Newton’s monolithic freeze framing of a deterministic universe. Introducing some relativity into the time component curbs the representational freedom issue…But it still suffers from the same material reifications due to representational illusions based on the arbitrary stability of perceived identity.
I agree with the author that even Poincaré gave Einstein too much credit and benefit of the doubt when it wasn’t awarded back to him. Einstein’s search for a cosmological constant, and an even more general theory, shows he didn’t consider it important to know the difference between the tools and the definitions of the tools. He didn’t see a difference between the tools he used to measure the universe and the universe itself.
Thanks to Poincaré’s quiet contribution we know how non-Euclidean space better fits our perception of spatial dimensionality. Something that allows Einstein’s relativity to be useful at all. Time as “t” is first and foremost a generalized social construct imposed by the socialization of the modern western civilization. A particular kind of temporal change in representational identity.
To see science and math as a prophetic measurement of the movement of objects in space, is to operationalize one particular way. To allow such paradigmatic domains representational definitions that arbitrarily change in time, but not in spatial identity, is to operationalize all of what we measure as materiality, one particular way. To make all that temporal simultaneity signifies, in its repetitive difference irrelevant, due to its lack of stable identifying representation over a linear form of causal time, is to misunderstand simultaneity, and even causality itself.
Below is a quote that concludes the book and eloquently summarizes the main thing that Poincaré understood that escaped Einstein.
“Poincaré had significantly advanced the Lorentz theory, "turning it in every direction" as he had said so often. In the process, bit by bit, he had grappled for years with changed notions of mass, length, and most dramatic-ally, time itself. More than anyone, he insisted both in his mathematics and in his philosophy that one could switch, according to circumstance, from Euclidian to non-Euclidean language. Shortly after Solvay, Poincaré even advanced understanding of the new and unsettling quantum discontinuity.
In Poincaré we face anyone but a change-abhoring conservative. But he contended that there were better and worse ways of handling innovation. The new physics, Poincaré was saying, had lost its way by abandoning, in its frantic race ahead, the consistent and principled base of any-of all-mechanics. The
"honest functions" and the differential equations that vouchsafed causality and intuition had been lost.
This was not a dispute over which law best fit the phe-nomena. It was a gulf that, for Poincaré, left Einstein and his supporters on the wrong side of "the very concept of natural law." Borrowing Poincaré's own earlier phrase, Einstein's quantum physics seemed less well suited for science than for a teratological museum.
Einstein's reaction to the Solvay encounter with Poincaré was swift and unflattering. A few weeks after Solvay, he confided his views to a friend: "H. A.
Lorentz is a marvel of intelligence and tact. He is a living work of art! In my opinion he was the most intelligent among the theoreticians present. Poincaré was simply negative in general, and, all his acumen notwithstanding, he showed little grasp of the situ-ation."? There was certainly no meeting of minds between them over the relativity theory. Their split over the quantum widened the chasm.
Yet Poincaré returned to Paris from Solvay in 1911 deeply impressed by Einstein. That November, Ein-stein, having only recently moved to Prague, was a candidate for a position at his alma mater, the Swiss Federal Institute of Technology. Setting aside any disquiet at Einstein's disturbing radicality, Poincaré intervened in his favor, assuring physicist Pierre Weiss that Einstein was "one of the most original minds I have known." Youth mattered little; the senior scientist judged Einstein to have "already taken a very honorable rank among the leading scholars of his time. What we must above all admire in him, is the facility with which he has adapted to new conceptions and from which he knows how to draw the consequences. He does not remain attached to classical principles, and, in the presence of a problem of physics, is prompt to envision all the possibilities.
This translates immediately in his mind into the prediction of new phenomena, susceptible of being one day verified by experiment. I do not want to say that all these predictions will remain impervious to the judgment of experiment when that judgment becomes possible. As he searches in all directions, one must, on the contrary, expect that the majority of the paths in which he embarks will be dead ends; but one must, at the same time, hope that one of the directions that he has indicated will be the right one; and that suffices. It is just so that one must proceed The role of mathematical physics is to pose questions properly, it is only experiment that can resolve them." This was a letter of the highest praise. "The future will show more and more the value of Mr. Einstein," Poincaré concluded, "and the university that finds a way to secure this young master is assured of drawing from it great honor."?
Beyond this statesmanly letter, it is impossible to say precisely what effect Poincaré's one meeting with Einstein had on the senior physicist. Poincaré's health was deteriorating, and he may at this time of enormous productivity also have had intimations of his own mortality. It may also be that Poincaré's later reflections upon Einstein's jarring new vision of physics at Solvay prompted the mathematician to think further on the value of the provisional, heuristic, result-oriented efforts that Einstein had employed to such effect. Just a few weeks after recommending Einstein to Weiss, on 11 December 1911, Poincaré wrote to the founding editor of Circolo matematico of Palermo. Still working on the three-body problem with which he had launched his career decades earlier, Poincaré reported to his correspondent that for two long years he had been struggling with the problem without much progress. He now had to pause, at least temporarily.
"It would be fine if I could be sure of being able to take it up again; at my age, I cannot vouch for that, and the results obtained, liable to put researchers on a new and unexplored track, seem to me too full of promises, despite the disappointments that they have caused me, for me to resign myself to sacrificing them." At fifty-seven, Poincaré was hardly old, but just a few years before, he had needed major prostate surgery. Would the editor be willing to publish an incomplete work, one that would state the problem and report partial results? (He would.) "What embarrasses me is that I will be obliged to put in a lot of fig-ures, precisely because I could not arrive at a general rule, but I only accumulated particular solutions." As Poincaré had so often insisted, visual-geometrical intuition could go where skeletal algebra could not yet tread
Poincaré judged these particular solutions to his lifelong problem "useful." They were more than that; the paper contributed foundational ideas to the establishment of topology, a new branch of mathemat-ics. Soon a young American mathematician, George D.
Birkhoff, proved the crucial conjecture that lay at the core of Poincaré's exploration. 10
Perhaps tacit echoes of Einstein may be audible in the last speech Poincaré gave on relativity, though the presentation never mentioned Einstein's name. On 4 May 1912, Poincaré spoke on "Space and Time" to an audience at the University of London. In forceful terms, he once again repeated: "The properties of time are therefore merely those of our clocks just as the properties of space are merely those of the measuring instruments." Over the past years, the ether had grown ever thinner in Poincaré's writings, as its role in the theory dwindled. Now, however, the all-pervasive substance simply evaporated into silence.
No rejection-but no mention of it, either. In his per-oration, Poincaré let the old mechanical "principle of relativity" fall away, replaced by the "principle of relativity according to Lorentz." Events simultaneous according to clocks coordinated in one frame of reference would not be simultaneous if measured by clocks coordinated in another.
Does this mean that Poincaré had abandoned the ether or become a thoroughgoing Einsteinian? No.
Having begun his presentation by asking if his earlier conclusions about space and time now needed to be revised in light of recent developments, he replied:
"Certainly not; we had adopted a convention because it seemed convenient and we had said nothing could constrain us to abandon it." But conventions are not God-given.
Today some physicists want to adopt a new conven-tion. It is not that they are constrained to do so; they consider this new convention more convenient; that is all. And those who are not of this opinion can legitimately retain the old one in order not to disturb their old habits. I believe, just between us, that this is what they shall do for a long time to come. 12
Poincaré's time to come was short. His medical difficulties came more frequently and more severely.
Nonetheless, when asked to accept the presidency of The French League of Moral Education and deliver its founding address on 26 June 1912, Poincaré characteristically accepted. For him, scientific prestige was inextricably associated with civic leadership and responsibility. In the midst of battles between anticlerical and clerical movements, in the face of an escalating conflict with the Germans in North Africa, even as the walls of Paris were plastered with partisan appeals, Poincaré sought principles that would undergird a unifying French morality. Against those ready to manipulate hatreds, Poincaré saw discipline as the only defense. Discipline-morality-was all that secured mankind against "an abyss of suffer-ings." "Mankind is ….. like an army at war," an army that must prepare for battle in peacetime, not at the last, too-late moment of engagement with the enemy.
Hatred could propel collisions among men, collisions that risked changing their faith. "What will happen if the new ideas which they adopt are those which their former teachers conveyed to them as the very negation of morality? Can this mental habit be lost in one day? ... Too old to acquire a new education, they shall lose the fruits of the old!"13 In morality, in physics, in mathematics, Poincaré wanted to build dramatic new structures, but he wanted to do so using the old bricks; he would employ, not discard, the legacy of an illustrious past.
Poincaré underwent surgery again on 9 July 1912, and for a few days friends and family hoped for a recovery. It never came; Poincaré died, following an embolism, on 17 July 1912. Dozens of éloges appeared across the world. Perhaps the most fitting monument was the most anonymous: later that year the Eiffel Tower began radiating its precision time sig-nal. Those pulses bathed the world in an expanding sphere of Hertzian light, fixing simultaneity (and longitude into Africa and across the Atlantic to North America on the basis of techniques that Poincaré had introduced into geodesy, epistemology, and physics.
Two Modernisms
Reflecting back on Henri Poincaré in 1954, Prince Louis de Broglie, the physicist who had shown that particles could act like waves, lamented that the great mathematician had just missed being the first to develop the theory of relativity in all its generality, "thus gaining for France the glory of that discovery." "It is impossible to be closer to the thought of Einstein," de Broglie judged. "And yet Poincaré did not take the decisive step; he left to Einstein the glory of grasping all the consequences of the principle of relativity and, in particular, of establishing, by a profound criticism of the measure of lengths and durations, the true physical character of the relation that the principle of relativity has between space and time. Why did Poincaré not come to the end of his thought? It is no doubt the turn, a little too critical, of his spirit, due perhaps to his education as pure mathematician..." For de Broglie, it was Poincaré's training as a mathematician that had led him to see science as no more than the informed and expeditious choice, on the basis of convenience, of one theory from among all logically equivalent ones. According to de Broglie, Poincaré failed to tread the better path laid down by the physicist's intuition. By de Broglie's lights, Poincaré was too much a mathematician, too indifferent to the real world to have formulated relativity as Einstein did.
My view? De Broglie's diagnosis is far too narrow.
I would argue that Poincaré did come to the "end of his thought," to an image of knowledge-includ-ing his view of mathematical knowledge-that carried with it a nineteenth-century optimism, a Third Republic Polytechnician's engaged, hopeful vision of a calculable, improvable, rational world. If anything, Poincaré paid too much attention to the real world: when he judged in 1898-99 that the corrections to Newtonian time were in principle necessary but too small to matter, it was because at that moment he was assessing the light-signal "relativistic" errors against the real-world "ordinary" longitude-timing errors. Yet to call Poincaré's approach "conservative" or "reactionary" is to miss the point; Poincaré's sight-line aimed directly toward the ideals of a revolutionary Enlightenment that, by century's end (Poin-caré's time), had grown into institutionalized French empire. All our great constructions eventually crack, Poincaré says on many occasions. But our response to these fissures, these crises, should not be the mysticism or the melancholy of the intellectual elites, but instead a redoubled effort to repair those breaks by the systematic application of reasoned action. As Poincaré saw it, the scientist-engineer could apply analytical reason as readily to the understanding of a coal-mine accident as to planetary motion, as easily to the mapping of the world as to the reconstruction of Lorentz's theory of moving electrons.
For Poincaré, the trunk of the tree of knowledge was precisely this engaged mechanics, an intuitively grounded mathematical understanding of nature that, at myriad points, shot branches into experiment and technology. Searching in a thousand ways, Poincaré aimed for an understanding of the world that could on the one hand speak to students trying to comprehend their place in an injured France and on the other hand to scientists, cartographers, and politicians struggling to wire together an empire that would bind Paris to Dakar, Haiphong, and Montreal. He wanted a mechanics of forces and energy, but one sufficient to undergird analysis of celestial mechanics, the shape of the earth, or the behavior of telegraph wires. As he reminded his fellow anciens polytechniciens in 1903, the required mixture was one of theory and action. In Poincaré's case that meant at one time responding to British telegraphic hegemony by fostering French radio signaling, at another by dismantling the unscientific indictment against Dreyfus with astronomical instruments and the calculus of probabilities.
His was a world where truth and the ultimate reality of things meant far less than the establishment of communicable, stable, durable relations- the kind of reliable relations that made action possible. As Poincaré put it, "science is only a classification and ... a classification can not be true, merely convenient. But it is true that it is convenient, it is true that it is so not only for me, but for all men; it is true that it will remain convenient for our descendants; it is true hective talit consists in he altions of,ingsole
A world of scientific rationality without metaphysical profundity: objective relations, not metaphysical objects.
For Poincaré, joining the abstract and concrete in this flat world of relations meant being able to negotiate hard-fought conventions in the human world.
Sorting and negotiating the needs and demands of railroad magnates, astronomers, physicists, and navigators lay front and center in the decimalization of time. And as a leading figure at the Bureau of Lon-gitude, Poincaré grasped time through the detailed, material procedures of engineering protocols: organ-izing, analyzing, reporting on the expeditions of the military-scientific colleagues he so admired as they hammered together observatory shacks in the high Andes or on the coastal stations of Senegal. Time, for Poincaré, resided in our world, our convenience, our exchange of optical and electrical telegraph sig-nals. The metaphysical world behind appearances was nothing. As he wrote in "The Measure of Time,"
"We ... choose these rules [of simultaneity] not because they are true but because they are the most convenient."
For Poincaré the choice of how to measure simultaneity made time richer, not poorer. It meant he could work the time concept back and forth among the protocols of longitude or decimalization, the abstractions of a science-inflected philosophy, and the principles of a new physics. "Let us watch [scientists (savants)] at work and look for the rules by which they investigate simultaneity," Poincaré urged. 16 This is precisely what Poincaré did as he struggled to synthesize the work of his circle of philosophers, physi-cists, and cartographers. Time-as-procedure stood in all three series:
Simultaneity is a convention, nothing more than the coordination of clocks by a crossed exchange of electromagnetic signals taking into account the transit time of the signal.”
Many philosophers and scientists like Poincaré could at least tell when there is no clear distinction between the tools of perception we use to observe phenomena and the phenomena itself. Definitions, variables, identities and representations have a way of territorializing time and projecting that onto space. A way of generalizing and compromising change, rather than observing each relative moment in its longer more impermanent context.
Einstein’s paradigm improved on Newton’s monolithic freeze framing of a deterministic universe. Introducing some relativity into the time component curbs the representational freedom issue…But it still suffers from the same material reifications due to representational illusions based on the arbitrary stability of perceived identity.
I agree with the author that even Poincaré gave Einstein too much credit and benefit of the doubt when it wasn’t awarded back to him. Einstein’s search for a cosmological constant, and an even more general theory, shows he didn’t consider it important to know the difference between the tools and the definitions of the tools. He didn’t see a difference between the tools he used to measure the universe and the universe itself.
Thanks to Poincaré’s quiet contribution we know how non-Euclidean space better fits our perception of spatial dimensionality. Something that allows Einstein’s relativity to be useful at all. Time as “t” is first and foremost a generalized social construct imposed by the socialization of the modern western civilization. A particular kind of temporal change in representational identity.
To see science and math as a prophetic measurement of the movement of objects in space, is to operationalize one particular way. To allow such paradigmatic domains representational definitions that arbitrarily change in time, but not in spatial identity, is to operationalize all of what we measure as materiality, one particular way. To make all that temporal simultaneity signifies, in its repetitive difference irrelevant, due to its lack of stable identifying representation over a linear form of causal time, is to misunderstand simultaneity, and even causality itself.
Below is a quote that concludes the book and eloquently summarizes the main thing that Poincaré understood that escaped Einstein.
“Poincaré had significantly advanced the Lorentz theory, "turning it in every direction" as he had said so often. In the process, bit by bit, he had grappled for years with changed notions of mass, length, and most dramatic-ally, time itself. More than anyone, he insisted both in his mathematics and in his philosophy that one could switch, according to circumstance, from Euclidian to non-Euclidean language. Shortly after Solvay, Poincaré even advanced understanding of the new and unsettling quantum discontinuity.
In Poincaré we face anyone but a change-abhoring conservative. But he contended that there were better and worse ways of handling innovation. The new physics, Poincaré was saying, had lost its way by abandoning, in its frantic race ahead, the consistent and principled base of any-of all-mechanics. The
"honest functions" and the differential equations that vouchsafed causality and intuition had been lost.
This was not a dispute over which law best fit the phe-nomena. It was a gulf that, for Poincaré, left Einstein and his supporters on the wrong side of "the very concept of natural law." Borrowing Poincaré's own earlier phrase, Einstein's quantum physics seemed less well suited for science than for a teratological museum.
Einstein's reaction to the Solvay encounter with Poincaré was swift and unflattering. A few weeks after Solvay, he confided his views to a friend: "H. A.
Lorentz is a marvel of intelligence and tact. He is a living work of art! In my opinion he was the most intelligent among the theoreticians present. Poincaré was simply negative in general, and, all his acumen notwithstanding, he showed little grasp of the situ-ation."? There was certainly no meeting of minds between them over the relativity theory. Their split over the quantum widened the chasm.
Yet Poincaré returned to Paris from Solvay in 1911 deeply impressed by Einstein. That November, Ein-stein, having only recently moved to Prague, was a candidate for a position at his alma mater, the Swiss Federal Institute of Technology. Setting aside any disquiet at Einstein's disturbing radicality, Poincaré intervened in his favor, assuring physicist Pierre Weiss that Einstein was "one of the most original minds I have known." Youth mattered little; the senior scientist judged Einstein to have "already taken a very honorable rank among the leading scholars of his time. What we must above all admire in him, is the facility with which he has adapted to new conceptions and from which he knows how to draw the consequences. He does not remain attached to classical principles, and, in the presence of a problem of physics, is prompt to envision all the possibilities.
This translates immediately in his mind into the prediction of new phenomena, susceptible of being one day verified by experiment. I do not want to say that all these predictions will remain impervious to the judgment of experiment when that judgment becomes possible. As he searches in all directions, one must, on the contrary, expect that the majority of the paths in which he embarks will be dead ends; but one must, at the same time, hope that one of the directions that he has indicated will be the right one; and that suffices. It is just so that one must proceed The role of mathematical physics is to pose questions properly, it is only experiment that can resolve them." This was a letter of the highest praise. "The future will show more and more the value of Mr. Einstein," Poincaré concluded, "and the university that finds a way to secure this young master is assured of drawing from it great honor."?
Beyond this statesmanly letter, it is impossible to say precisely what effect Poincaré's one meeting with Einstein had on the senior physicist. Poincaré's health was deteriorating, and he may at this time of enormous productivity also have had intimations of his own mortality. It may also be that Poincaré's later reflections upon Einstein's jarring new vision of physics at Solvay prompted the mathematician to think further on the value of the provisional, heuristic, result-oriented efforts that Einstein had employed to such effect. Just a few weeks after recommending Einstein to Weiss, on 11 December 1911, Poincaré wrote to the founding editor of Circolo matematico of Palermo. Still working on the three-body problem with which he had launched his career decades earlier, Poincaré reported to his correspondent that for two long years he had been struggling with the problem without much progress. He now had to pause, at least temporarily.
"It would be fine if I could be sure of being able to take it up again; at my age, I cannot vouch for that, and the results obtained, liable to put researchers on a new and unexplored track, seem to me too full of promises, despite the disappointments that they have caused me, for me to resign myself to sacrificing them." At fifty-seven, Poincaré was hardly old, but just a few years before, he had needed major prostate surgery. Would the editor be willing to publish an incomplete work, one that would state the problem and report partial results? (He would.) "What embarrasses me is that I will be obliged to put in a lot of fig-ures, precisely because I could not arrive at a general rule, but I only accumulated particular solutions." As Poincaré had so often insisted, visual-geometrical intuition could go where skeletal algebra could not yet tread
Poincaré judged these particular solutions to his lifelong problem "useful." They were more than that; the paper contributed foundational ideas to the establishment of topology, a new branch of mathemat-ics. Soon a young American mathematician, George D.
Birkhoff, proved the crucial conjecture that lay at the core of Poincaré's exploration. 10
Perhaps tacit echoes of Einstein may be audible in the last speech Poincaré gave on relativity, though the presentation never mentioned Einstein's name. On 4 May 1912, Poincaré spoke on "Space and Time" to an audience at the University of London. In forceful terms, he once again repeated: "The properties of time are therefore merely those of our clocks just as the properties of space are merely those of the measuring instruments." Over the past years, the ether had grown ever thinner in Poincaré's writings, as its role in the theory dwindled. Now, however, the all-pervasive substance simply evaporated into silence.
No rejection-but no mention of it, either. In his per-oration, Poincaré let the old mechanical "principle of relativity" fall away, replaced by the "principle of relativity according to Lorentz." Events simultaneous according to clocks coordinated in one frame of reference would not be simultaneous if measured by clocks coordinated in another.
Does this mean that Poincaré had abandoned the ether or become a thoroughgoing Einsteinian? No.
Having begun his presentation by asking if his earlier conclusions about space and time now needed to be revised in light of recent developments, he replied:
"Certainly not; we had adopted a convention because it seemed convenient and we had said nothing could constrain us to abandon it." But conventions are not God-given.
Today some physicists want to adopt a new conven-tion. It is not that they are constrained to do so; they consider this new convention more convenient; that is all. And those who are not of this opinion can legitimately retain the old one in order not to disturb their old habits. I believe, just between us, that this is what they shall do for a long time to come. 12
Poincaré's time to come was short. His medical difficulties came more frequently and more severely.
Nonetheless, when asked to accept the presidency of The French League of Moral Education and deliver its founding address on 26 June 1912, Poincaré characteristically accepted. For him, scientific prestige was inextricably associated with civic leadership and responsibility. In the midst of battles between anticlerical and clerical movements, in the face of an escalating conflict with the Germans in North Africa, even as the walls of Paris were plastered with partisan appeals, Poincaré sought principles that would undergird a unifying French morality. Against those ready to manipulate hatreds, Poincaré saw discipline as the only defense. Discipline-morality-was all that secured mankind against "an abyss of suffer-ings." "Mankind is ….. like an army at war," an army that must prepare for battle in peacetime, not at the last, too-late moment of engagement with the enemy.
Hatred could propel collisions among men, collisions that risked changing their faith. "What will happen if the new ideas which they adopt are those which their former teachers conveyed to them as the very negation of morality? Can this mental habit be lost in one day? ... Too old to acquire a new education, they shall lose the fruits of the old!"13 In morality, in physics, in mathematics, Poincaré wanted to build dramatic new structures, but he wanted to do so using the old bricks; he would employ, not discard, the legacy of an illustrious past.
Poincaré underwent surgery again on 9 July 1912, and for a few days friends and family hoped for a recovery. It never came; Poincaré died, following an embolism, on 17 July 1912. Dozens of éloges appeared across the world. Perhaps the most fitting monument was the most anonymous: later that year the Eiffel Tower began radiating its precision time sig-nal. Those pulses bathed the world in an expanding sphere of Hertzian light, fixing simultaneity (and longitude into Africa and across the Atlantic to North America on the basis of techniques that Poincaré had introduced into geodesy, epistemology, and physics.
Two Modernisms
Reflecting back on Henri Poincaré in 1954, Prince Louis de Broglie, the physicist who had shown that particles could act like waves, lamented that the great mathematician had just missed being the first to develop the theory of relativity in all its generality, "thus gaining for France the glory of that discovery." "It is impossible to be closer to the thought of Einstein," de Broglie judged. "And yet Poincaré did not take the decisive step; he left to Einstein the glory of grasping all the consequences of the principle of relativity and, in particular, of establishing, by a profound criticism of the measure of lengths and durations, the true physical character of the relation that the principle of relativity has between space and time. Why did Poincaré not come to the end of his thought? It is no doubt the turn, a little too critical, of his spirit, due perhaps to his education as pure mathematician..." For de Broglie, it was Poincaré's training as a mathematician that had led him to see science as no more than the informed and expeditious choice, on the basis of convenience, of one theory from among all logically equivalent ones. According to de Broglie, Poincaré failed to tread the better path laid down by the physicist's intuition. By de Broglie's lights, Poincaré was too much a mathematician, too indifferent to the real world to have formulated relativity as Einstein did.
My view? De Broglie's diagnosis is far too narrow.
I would argue that Poincaré did come to the "end of his thought," to an image of knowledge-includ-ing his view of mathematical knowledge-that carried with it a nineteenth-century optimism, a Third Republic Polytechnician's engaged, hopeful vision of a calculable, improvable, rational world. If anything, Poincaré paid too much attention to the real world: when he judged in 1898-99 that the corrections to Newtonian time were in principle necessary but too small to matter, it was because at that moment he was assessing the light-signal "relativistic" errors against the real-world "ordinary" longitude-timing errors. Yet to call Poincaré's approach "conservative" or "reactionary" is to miss the point; Poincaré's sight-line aimed directly toward the ideals of a revolutionary Enlightenment that, by century's end (Poin-caré's time), had grown into institutionalized French empire. All our great constructions eventually crack, Poincaré says on many occasions. But our response to these fissures, these crises, should not be the mysticism or the melancholy of the intellectual elites, but instead a redoubled effort to repair those breaks by the systematic application of reasoned action. As Poincaré saw it, the scientist-engineer could apply analytical reason as readily to the understanding of a coal-mine accident as to planetary motion, as easily to the mapping of the world as to the reconstruction of Lorentz's theory of moving electrons.
For Poincaré, the trunk of the tree of knowledge was precisely this engaged mechanics, an intuitively grounded mathematical understanding of nature that, at myriad points, shot branches into experiment and technology. Searching in a thousand ways, Poincaré aimed for an understanding of the world that could on the one hand speak to students trying to comprehend their place in an injured France and on the other hand to scientists, cartographers, and politicians struggling to wire together an empire that would bind Paris to Dakar, Haiphong, and Montreal. He wanted a mechanics of forces and energy, but one sufficient to undergird analysis of celestial mechanics, the shape of the earth, or the behavior of telegraph wires. As he reminded his fellow anciens polytechniciens in 1903, the required mixture was one of theory and action. In Poincaré's case that meant at one time responding to British telegraphic hegemony by fostering French radio signaling, at another by dismantling the unscientific indictment against Dreyfus with astronomical instruments and the calculus of probabilities.
His was a world where truth and the ultimate reality of things meant far less than the establishment of communicable, stable, durable relations- the kind of reliable relations that made action possible. As Poincaré put it, "science is only a classification and ... a classification can not be true, merely convenient. But it is true that it is convenient, it is true that it is so not only for me, but for all men; it is true that it will remain convenient for our descendants; it is true hective talit consists in he altions of,ingsole
A world of scientific rationality without metaphysical profundity: objective relations, not metaphysical objects.
For Poincaré, joining the abstract and concrete in this flat world of relations meant being able to negotiate hard-fought conventions in the human world.
Sorting and negotiating the needs and demands of railroad magnates, astronomers, physicists, and navigators lay front and center in the decimalization of time. And as a leading figure at the Bureau of Lon-gitude, Poincaré grasped time through the detailed, material procedures of engineering protocols: organ-izing, analyzing, reporting on the expeditions of the military-scientific colleagues he so admired as they hammered together observatory shacks in the high Andes or on the coastal stations of Senegal. Time, for Poincaré, resided in our world, our convenience, our exchange of optical and electrical telegraph sig-nals. The metaphysical world behind appearances was nothing. As he wrote in "The Measure of Time,"
"We ... choose these rules [of simultaneity] not because they are true but because they are the most convenient."
For Poincaré the choice of how to measure simultaneity made time richer, not poorer. It meant he could work the time concept back and forth among the protocols of longitude or decimalization, the abstractions of a science-inflected philosophy, and the principles of a new physics. "Let us watch [scientists (savants)] at work and look for the rules by which they investigate simultaneity," Poincaré urged. 16 This is precisely what Poincaré did as he struggled to synthesize the work of his circle of philosophers, physi-cists, and cartographers. Time-as-procedure stood in all three series:
Simultaneity is a convention, nothing more than the coordination of clocks by a crossed exchange of electromagnetic signals taking into account the transit time of the signal.”
June 14, 2020
Time, Time, Time. Gets me thinking about the old Chambers Brother Song 'Time has Come Today'. Anyway this strange book about time had some good moments although poorly organized, erratic and seemed almost in search of a reason to be written. Part biography, part history, part science and doing none of them particularly well. He is an obvious admirer of the great French polymath Henri Poincare and perhaps less so of the immortal Albert E. There story wanders about through parts of Poincare's early career, the intense late 19th century efforts to synchronize clocks using telegraph and radio then veers somewhat briefly almost into the seminal 1905 paper 'On the Electrodynamics of Moving Bodies' and the world changing concept of relativity. His description of Einstein's time in the Bern Patent office and how it helped shape his thinking about time was among the better sections. And there are interesting nuggets throughout, such as this quote in a letter by Einstein; 'Authority gone to one's head is the greatest enemy of truth'. The science 'leaders' of today should remember that (yes, looking at you, Fauci). The book is well footnoted and referenced which is a plus. But basically this was a very uneven effort, often repetitive and ultimately disappointing because I hoped for a better effort to clarify a fascinating topic. I wavered between 2 and 3 stars, and 2.5 would be more accurate from my point of view.
February 1, 2010
So I started reading this book because I thought it was going to be about the development of the theory of relativity. And it was, tangentially. When I realized that it was actually mostly about coordinating clocks and the author's deep, abiding love for Henri Poincare, I was amused and kept reading. Somewhere along the way I stopped being amused and got bored, but then my OCD kicked in. It's really hard for me to abandon a book. And that is how I ended up reading this silly ode to simultaneity.
If I could tell the author anything, it would be that there is a reason that Einstein gets the credit for the theory of relativity and Poincare does not, and that reason is that Einstein came up with it and Poincare did not. Life is unfair like that.
If I could tell the author anything, it would be that there is a reason that Einstein gets the credit for the theory of relativity and Poincare does not, and that reason is that Einstein came up with it and Poincare did not. Life is unfair like that.
December 30, 2011
There were moments of this book that I absolutely loved, and some fascinating insights regarding topics as the practical underpinnings of some of the radical turns in theoretical physics (e.g., how Einstein's career as a patent examiner affected his approach to physics) and the controversial nature of the very concept of simultaneity.
Unfortunately, far too much time is spent in a blow-by-blow of Poincare's career. While perhaps an important contribution to the history of science, this stuff was just a bit more than I felt I needed to know on the topic.
But if you're interested in issues like simultaneity, relativity, and the rise of intellectual modernity, this book may be worth your time.
Unfortunately, far too much time is spent in a blow-by-blow of Poincare's career. While perhaps an important contribution to the history of science, this stuff was just a bit more than I felt I needed to know on the topic.
But if you're interested in issues like simultaneity, relativity, and the rise of intellectual modernity, this book may be worth your time.
January 21, 2018
Galison corners time from every angle. I learned how time was first synchronized across towns and continents, which spilled into international politics and religion and astronomy, and how Einstein and Poincaré and Lorentz and others conceptualized time in the most abstract ways, which was grounded by mine collapses and Swiss watchmakers and sabotaged telegraph cables.
The writing is often difficult to read but occasionally punctured by a lovely sentence. I would need to reread this to really understand the timeline and events that are the pieces of this multi-century cross-continental puzzle, but I gained an appreciation for the historical complexity of the already-mind-bending concept of time.
The writing is often difficult to read but occasionally punctured by a lovely sentence. I would need to reread this to really understand the timeline and events that are the pieces of this multi-century cross-continental puzzle, but I gained an appreciation for the historical complexity of the already-mind-bending concept of time.
November 5, 2016
This book is part metaphysical musing on time and part historical account of actions taken to standardize time in the late nineteenth century. The author presumes the reader is deeply familiar with Poincaré's papers on time and as such, I got lost quickly. Put the book aside before I even got to the Einstein section.
But, if you want an account of why the zero degree meridian ended up at Greenwich and not Paris, despite France's recent (in the 1870s) victory at standardizing on the meter, this is the book for you
But, if you want an account of why the zero degree meridian ended up at Greenwich and not Paris, despite France's recent (in the 1870s) victory at standardizing on the meter, this is the book for you
February 28, 2009
Quite good. Effortlessly expansive. Not so sure I agree entirely with some of the particulars of his argument, but very veyr good nonetheless.
March 4, 2018
I wasn't sure where this book was going for awhile, but it came together in the end. It is a bit of an odd connection (Poincaré and Einstein), but it worked in the end. The focus is on clock synchronization which isn't all that obvious at first. But it comes together. What I found particularly fascinating about the book, though, is that it does an excellent job of tearing down the myth that either one of these great physicists was absent-mindedly lost in pure thought all the time. Far from being a lonely, isolated figure at the Bern patent office, Einstein was fully engaged in his work and it contributed to the development of a number of his theories. He actually served at the patent office for seven years and even began his work on general relativity while still there. Likewise, Poincaré worked on things like mine safety and longitude determination until his death. Both men were firmly grounded in practical matters yet we seem to have built these mythical images of them as pure thinkers. Anyway, the book is worth a read, though I do find Galison a bit too long-winded at times.
January 16, 2022
Einstein's Clocks, Poincare's Maps is, ironically, the most oddly out-of-synch book title I've seen when it comes to reflecting the content of the work. This was a story of establishing commonality of time and measuring longitude. "Poincare's maps" occupied less than 5 pages (although I do recognize the broader application to his contribution to longitude measurement), and "Einsteins clocks" was a mechanism to bring a universally-known scientific name to a French science apologist's account of Poincare's accomplishments.
Had this book simply told the story of synchronizing clocks and learning how to measure longitude, it would have been a worthwhile read. The inclusion of and stretched comparisons to Einstein left the work disjointed, as well as leaving the reader with the impression the author has an axe to grind. Mr Galison seems almost personally offended that Einstein dismissed Poincare as a scientific relic whose relevance had faded.
I would recommend the 40% of this book that dealt with time and longitude. 2/5 seems an appropriate rating...
Had this book simply told the story of synchronizing clocks and learning how to measure longitude, it would have been a worthwhile read. The inclusion of and stretched comparisons to Einstein left the work disjointed, as well as leaving the reader with the impression the author has an axe to grind. Mr Galison seems almost personally offended that Einstein dismissed Poincare as a scientific relic whose relevance had faded.
I would recommend the 40% of this book that dealt with time and longitude. 2/5 seems an appropriate rating...
April 4, 2023
Not for the faint-hearted.
However, as both a scientist and an engineer this was an enlightening book. Looking through the lens of relativity, it told a story of how technological challenges and science influenced each other. This serves as an important example that neither exist in a limbo, and that we should always looking in both directions when solving problems.
As someone interested in science in general, this book has also much to offer. The philosophy and meaning of time, the realization of time zones, the relation between early-20th century empires and modern technology all have a place in this book.
Yet, it should also be noted that it is sometimes quite dense and that historical characters are quickly brought up and then never mentioned again, as their role was limited. This makes the book slightly tougher than it should be, so finally I would rather rate this is 4.5 starts.
However, as both a scientist and an engineer this was an enlightening book. Looking through the lens of relativity, it told a story of how technological challenges and science influenced each other. This serves as an important example that neither exist in a limbo, and that we should always looking in both directions when solving problems.
As someone interested in science in general, this book has also much to offer. The philosophy and meaning of time, the realization of time zones, the relation between early-20th century empires and modern technology all have a place in this book.
Yet, it should also be noted that it is sometimes quite dense and that historical characters are quickly brought up and then never mentioned again, as their role was limited. This makes the book slightly tougher than it should be, so finally I would rather rate this is 4.5 starts.
December 28, 2022
It is probably better than two stars. But somehow I lost interest in this book immediately after I got Covid19, the second day on this book. I was so tortured by the virus that I stopped reading it for almost a week. After recovery, I found that I could feel any want to read it. And actually I felt it hard to grasp what the author is trying to say. He seems to have done a lot of decent research about his topics, but he didn't put it in an easy to follow way. A lot of pages for a sub topic and too many long quotes, too many secondary characters in and out, so it reads really boring and I don't know the gist of the whole book. It doesn't have much to do with Einstein theory and more about time syndicifcation.
Anyway, partly due to covid 19, and partly to this book's boring writing style, I finished my 2022 reading life with this stupid book.
Anyway, partly due to covid 19, and partly to this book's boring writing style, I finished my 2022 reading life with this stupid book.
October 8, 2022
This book is something of an amalgam: set alongside parallel biographies of Einstein and Poincare (I kept waiting to read about the cross-fertilization of their ideas, but it seems there was little direct contact between the two) is a comprehensive history of the standardization of time in the 19th century. The latter has its surprises (apparently Paris and Vienna in the late 19th century were laced with pneumatic tubes carrying puffs of air that gave the "correct" time) but lags in places (e.g., the blow-by-blow account of what were essentially bureaucratic debates in France). This is not the book for the layman curious about the special theory of relativity and the story of its development; I would direct that reader to Einstein's own Theory of Relativity of 1920.
March 25, 2021
The topic of discovering longitude, how we developed accurate maps, and how we developed accurate clocks is a surprisingly fascinating one. Unfortunately, though, the writing in the book sometimes drags, and the speculation on the lives of Poincare and Einstein felt unnecessary and shoehorned in. So my final review: all in all, very informative, but not perhaps not the most entertaining way to get the information. Maybe read Dava Sobel's Longitude instead.
Full review: https://acallidryas.wordpress.com/201...
acallidryas.wordpress.com
Full review: https://acallidryas.wordpress.com/201...
acallidryas.wordpress.com
January 10, 2024
Einstein tu figuruje spíš jen jako lákadlo v titulu, řekla bych.
Ale hodně mě zaujalo řešení synchronizace časů a jak na to.
Dnes, kdy už ani nepřemýšlíme, jak těžké někdy mohlo být sychronizovat hodiny mezi Amerikou a Evropou. V době, kdy zprávy napříč kontinenty putují ve velkém rychleji než telegraficky, už nás ani nenapadne, jak vůbec není automatické, že hodina má 60 minut, nultý poledník je zrovna v Greenwichi...
Tato kniha popisuje boje, které ustanovily tyto pro nás samozřejmé skutečnosti. A není to ani zas tak dávno...
Hodně zajímavá knížka.
Ale hodně mě zaujalo řešení synchronizace časů a jak na to.
Dnes, kdy už ani nepřemýšlíme, jak těžké někdy mohlo být sychronizovat hodiny mezi Amerikou a Evropou. V době, kdy zprávy napříč kontinenty putují ve velkém rychleji než telegraficky, už nás ani nenapadne, jak vůbec není automatické, že hodina má 60 minut, nultý poledník je zrovna v Greenwichi...
Tato kniha popisuje boje, které ustanovily tyto pro nás samozřejmé skutečnosti. A není to ani zas tak dávno...
Hodně zajímavá knížka.
March 4, 2024
An interesting topic, definitely worth exploring, yet spoiled by bloated writing. More often than not, whereas getting to the point might take a page or two the author instead decided that it would be much more fun for him to write twenty, jumping back and forth in time, places and characters.
This results in a book difficult to read and like, despite my own background education in the topic. A shame.
This results in a book difficult to read and like, despite my own background education in the topic. A shame.
August 10, 2022
I picked this book hoping to learn more about the science behind Einstein's theories on time and relativity. Instead it turned out to be part-science, part-history and part-biography of Einstein and Poincare's works. If done well (as in Microbe Hunters by Paul de Kruif), this is a combination I do not mind. However Galison's writing style is too tortuous for my taste.
DNFed at about 20%.
DNFed at about 20%.
August 7, 2023
A grand history of clock synchronization from the perspective of two masters of physics and rigorous logic. The book begins and ends well. The mid-core is historical but tedious within a framework of world time.
September 8, 2019
As an engineer and research scientist I found this book extremely interesting. It does a good job explains the complex theories of Einstein and Poincare and how history links them together.
April 17, 2020
Interesting topic. Not so interesting writing.
February 26, 2021
I really enjoyed this book! I learned a lot about the worlds of Poincaré and Einstein and how those worlds impacted how they thought about relativity.
Want to read
April 29, 2022Coen
October 12, 2022
Fantastic to learn about the central premise, but much of the book was dry and not-relevant passages.
November 20, 2022
Information provided on subject was good
The subject matter was good, I felt that at times the author was a bit long winded and off subject
The subject matter was good, I felt that at times the author was a bit long winded and off subject
August 23, 2023
Fascinating topic, but presented in a confusing and somewhat scattered fashion.
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