A Dutch review

A review published earlier this year in Delachendetheoloog:

'Mijn opa las geen romans. In zijn tijd waren boeken en tijdschriften onbetaalbaar. Omdat de mensen bovendien hard moesten werken was er weinig tijd om te lezen. Hij koos zijn lectuur daarom zorgvuldig uit. Zijn voorkeur ging uit naar ‘serieuze’ boeken. Romans gingen nergens over en waren het geld en de aandacht niet waard.

Tegenwoordig is de keus tussen ‘serieuze’ boeken en ‘belletrie’ niet zo wezenlijk meer. Het aanbod van populair-wetenschappelijke boeken is inmiddels zo groot en de boeken zijn zo goed geschreven en gecomponeerd, dat je ‘gewone’ romans met een gerust hart links kunt laten liggen. Het spreekt voor zich dat het genre van het populair-wetenschappelijke boek het goed doet: wij hebben goede leraren nodig om de wetenschappelijke ontwikkelingen te kunnen volgen.

Het boek Quantum van Manjit Kumar is het zoveelste bewijs van de uitstekende kwaliteit van het populair-wetenschappelijke boek. Het boek bevat alles wat een lezer zich kan wensen. Fundamentele inzichten over de inrichting van de werkelijkheid, dramatische ontwikkelingen tussen de grootste geleerden van de vorige eeuw en wijsgerige bespiegelingen over de betekenis van de beschreven gebeurtenissen.

Het boek doet het ontstaan van de kwantummechanica uit de doeken. De geschiedenis van de kwantummechanica wordt vermengd met karaktertekeningen van de belangrijkste geleerden die hebben bijgedragen aan de ontwikkeling van deze theorie en, vooral, over de scheuring die deze theorie veroorzaakt heeft tussen deze geleerden. Het hoogtepunt van dit boek is een beschrijving (alsof je er zelf bij bent) van de Solvay conferentie van 1927, wanneer Bohr en Einstein met elkaar twisten over de vraag of de kwantummechanica compleet is. Kumar bestrijdt het beeld van Einstein als een koppige, oude dwaas die meende dat de kwantummechanica onwaar was. Einstein heeft het formalisme van Heisenberg vrijwel onmiddellijk aanvaard en de experimenten hadden hem er van overtuigd dat de theorie goed was. De theorie geeft de juiste uitkomsten, maar: de theorie geeft ons niet het juiste inzicht in de werkelijkheid! En daarover ging het belangrijke debat tussen Einstein en Bohr. De vraag die de twee verdeelde was of de theorie volledig is en ons alles over de werkelijkheid zelf zegt.

Het debat tussen Einstein en Bohr was feitelijk geen strikt debat over fysische vraagstukken, maar een wijsgerig dispuut over de vraag hoe onze werkelijkheid is ingericht en over de vraag hoe diep de fysicus kan doordringen tot deze werkelijkheid. De auteur van dit boek is overigens uitstekend op de hoogte van dit deelgebied. Hij is fysicus en filosoof. Persoonlijk blijf ik het opvallend vinden dat uit zijn boek blijkt dat alle fysici in de 19eeuw en aan het begin van de 20ste eeuw een levendige belangstelling hebben voor de wijsbegeerte. Planck, Einstein, Heisenberg, Schrodinger, Bohr en alle anderen hebben zich, volgens Kumar, tijdens hun opleiding verdiept in het werk van filosofen. De zakelijke en anti-wijsgerige houding van Weinberg, Feynman en Hawking tref je bij Einstein en Bohr niet aan.

Volgens Niels Bohr moet een natuurkundige zich niet afvragen hoe de werkelijkheid ‘onder de oppervlakte' is. Het heeft alleen maar zin om over de wereld van het kleinste te spreken in termen van meetresultaten. Als de fysicus de beslissing neemt om bepaalde aspecten van de subatomaire werkelijkheid te meten, bemoeit hij zich actief met de natuur: de onderzoeker is niet langer een neutrale waarnemer, maar hij (bedoeld wordt: zijn meetapparatuur) maakt onderdeel uit van deze natuur. Einstein kon niet leven met deze uitleg. Hij meende dat de werkelijkheid op subatomair zich niet anders gedraagt dan de dagelijkse of ‘klassieke’ werkelijkheid. Je moet in staat zijn om de werkelijkheid zelf te bestuderen. De kleinste deeltjes hebben alle eigenschappen die ‘gewone’ tennisballen ook hebben. Het probleem was dat de kwantummechanica, ondanks dat het formalisme juist is, ons geen volledig beeld gaf van de werkelijkheid.

De Salvoy conferentie van 1927 was geheel gewijd aan de ‘nieuwe’ kwantummechanica. Alle geleerden keken naar Bohr, de koning van de kwantummechanica, en Einstein, die beschouwd werd als de paus van de fysica. Op de conferentie zelf zei Einstein weinig. Maar Bohr en Einstein logeerden in hetzelfde hotel. En in de avonden en de ochtenden waren ze niet in staat om elkaar met rust te laten. Einstein bedacht ingenieuze argumenten waaruit moest blijken dat de nieuwe fysica onvolledig is: het was een goede rekenmethode, maar beslist geen theorie die ons interessante fysische inzichten gaf in wat zich afspeelt op subatomair niveau.

De tegenvoorbeelden van Einstein hielden Bohr uit de slaap. Gedurende de nacht was hij bezig om een deugdelijk weerwoord te bedenken. Een enkele keer vond hij het antwoord pas in de ochtend. Maar uiteindelijk droogde de stroom bedenkingen van Einstein op. Hij weigerde echter om zijn standpunt te veranderen. De nieuwe theorie was in zijn ogen nu eenmaal onvolledig.
Kumar beschrijft hoe het meningsverschil tussen Einstein en Bohr zich voortsleept door de jaren heen. Waar mogelijk zochten de twee geleerden elkaar op. Maar uiteindelijk lukte het Einstein niet om formeel aan te tonen dat de theorie onvolledig is. Hij weigerde echter om zijn zienswijze te veranderen. Dit leverde hem bij de jongere generatie fysici de naam op een halsstarrige en ouderwetse man te zijn- dit strenge oordeel komt begrijpelijkerwijs voort uit teleurstelling over het feit dat de beroemdste fysicus het belang van hun werk niet wil erkennen.

Bohr en Einstein bleven vrienden van elkaar en ze respecteerden elkaar zeer. Maar de relatie bekoelde wel door het aanhoudende onderlinge meningsverschil. Einstein weigerde op het laatst zelfs om nog uitgebreid te twisten over de kwantummechanica. De laatste maal ontmoetten Bohr en Einstein elkaar bij toeval. Bohr was op bezoek bij een collega van hen die, evenals Einstein, werkzaam was op het Princeton instituut. Opeens sloop Einstein de kamer van de collega binnen om stiekum wat tabak te nemen uit de tabakspot die op tafel stond. Enige tijd later werd Einstein ziek. Hij weigerde zich te laten behandelen. Nauwelijks een jaar later stierf ook Bohr. Hoe belangrijk het oordeel van Einstein voor Bohr altijd geweest is bleek volgens Kumar uit de tekening die op het bord in zijn werkkamer stond: een van Einsteins ingenieuze tegenvoorbeelden.

Pas na de dood van Bohr en Einstein werd het geschil met fysische middelen beslecht. De jonge fysicus Bell, door Kumar op sympathieke wijze beschreven, ontdekte hoe men met een experiment zou kunnen vaststellen of non-localiteit –er lijkt op subatomair niveau geen ‘afstand’ te bestaan- een 'echte' eigenschap is van de kwanta. Uit de experimenten van Aspect blijkt vervolgens dat de klassieke visie van Einstein niet te verdedigen is.

Drama en natuurkunde zijn in dit boek zo ideaal met elkaar verweven dat je zowel de mensen die een hoofdrol hebben gespeeld goed leert kennen als de ontwikkeling van de fysica leert begrijpen en de daarmee gepaard gaande filosofische en fysische problemen. Kumar is in staat om de fysica op een zakelijke manier uit te leggen, zodat je voldoende op de hoogte bent van de problemen waar Einstein en Bohr zich het hoofd over breken. Hij bedient zich van een droge, zakelijke stijl. Zijn verteltrant is echter in het geheel niet sober. Het boek is meeslepend, wordt hier en daar zelfs ‘dramatisch’ zonder sentimenteel te worden. Zo spannend kan wetenschap dus zijn!'

If anyone out there reads Dutch, do let me know what it really says! I have a vague idea via Google translate.

Another review of Le grand roman de la physique quantique

A blog review by ErMa:

'L'histoire du making of de l'équation célébrissime, ces quelques signes abstrus ayant hanté les nuits de bon nombre de taupins et qui figurent désormais au patrimoine de l'humanité :






Disons-le tout de go, ce bouquin est passionnant, car il réunit trois ingrédients essentiels :

1) Un sujet (scientifique) d'intérêt et d'envergure : l'histoire d'une révolution conceptuelle majeure dans l'histoire de l'humanité, initiée en Allemagne au début du XXe siècle. Un changement de paradigme, illustré par l'émergence à marche forcée, au fil d'expériences de pensée d'une subtilité diabolique et de confirmations expérimentales d'une précision époustouflante, d'un cadre conceptuel contraire à nos intuitions, dans lequel le déterminisme (si rassurant) n'a plus sa place. Une démarche que certains, notamment le plus illustre d'entre eux (Einstein) réfuteront avec obstination jusqu'à leur mort : "Dieu ne joue pas aux dés".

Pourtant, malgré tout, la théorie aura déjoué toutes les tentatives de remise en question et gouverne actuellement et de façon silencieuse nombre d'applications de notre vie de tous les jours, notamment tout ce qui a trait à l'électronique.

2) L'Histoire, avec un grand H. Celle encore récente (moins de cent ans). Une époque où la science européenne rayonnait sur le monde et où son épicentre se situait en Allemagne, plus précisément du côté de Göttingen et Berlin. On sait ce qu'il advint par la suite. La montée de l'hitlérisme, l'exil des savants, le désastre de la deuxième guerre mondiale, la résurgence de l'autre côté de l'Atlantique du coté de Princeton. Oui, ce bouquin a également le petit parfum amer du paradis perdu...

3) Et puis enfin, l'histoire avec un petit h. Le destin individuel d'êtres de chair et de sang qui émergent derrière les figures tutélaires désormais inscrites dans nos encyclopédies : Bohr, de Broglie, Heisenberg, Schrödinger, Dirac, Pauli, avec, en contrepoint de leurs fulgurances, leurs faiblesses, leurs entêtements, leurs emportements, leurs erreurs.

Au delà de la vulgarisation d'un concept - pourtant a priori pas facile à comprendre - et réussie avec virtuosité, le succès de l'entreprise tient au talent déployé par Manjit Kumar pour faire de cette matière brute un véritable roman axé sur la psychologie de personnages hors du commun rendus à leur condition d'hommes comme vous et moi, en prise directe avec le grand souffle de l'histoire.

Un bel exemple de pédagogie à méditer. A une époque où il est de bon ton de s'auto-proclamer "nul en maths", rêvons qu'il puisse s'agir d'une leçon pour les pédagogistes de tous poils, apprentis sorciers participant au suicide actuel de l'éducation nationale, soixante ans seulement après la mort d'Einstein.'

L' Express review of the French Edition of Quantum

A review of the French edition of Quantum, or Le grand roman de la physique quantique as it's called in France, published in June but just forwarded to me by a friend:

'Bruxelles, octobre 1927. L'élite des physiciens de la planète est réunie au parc Léopold pour le congrès le plus important et le plus dramatique de la physique moderne. Dix-sept des vingt- neuf personnalités sont des Prix Nobel ou de futurs Nobel, dont Marie Curie, seule femme de cet aréopage d'hommes. Thème officiel : électrons et photons. En réalité, ces savants doivent accepter ou rejeter les premiers éléments de la physique quantique. Et remiser au placard les théories de la relativité qui ont valu à Einstein son prix Nobel en 1921. C'est un choc de titans, chacun affûtant ses armes pour ou contre le "quantum" pour lequel Max Planck a reçu le Nobel en 1919. La plupart de ces hommes se connaissent, ont même travaillé ensemble. Pourtant, la lutte sera sans merci. Acculé par ses pairs, Einstein se bat comme un lion.

Le talent de Manjit Kumar, physicien et philosophe, est de nous faire vivre cette bataille en direct, comme les étapes qui l'ont précédée et les années de conflit qui ont suivi. Il nous fait entrer dans l'intimité de ces génies, leurs origines, leurs engagements, leur passion pour cette science qui est en train de vivre sa plus grande révolution. On les suit depuis l'enfance jusqu'à la recherche de l'université européenne ou américaine qui veut bien les accueillir pour des travaux rarement pris au sérieux. Alors qu'ils ont donné naissance à tout ce qui fonde la modernité, depuis l'atome jusqu'à l'ordinateur. L'arrivée de Hitler au pouvoir en Allemagne force les savants juifs à s'exiler. Dans les années 1950, la commission McCarthy chasse d'Amérique les chercheurs de gauche.
L'auteur analyse avec brio les différentes thèses, expose les méthodes. Il sait aussi remettre dans son contexte l'apostrophe célèbre d'Einstein - "Dieu ne joue pas aux dés" - et l'invention par Erwin Schrödinger de ce chat mythique, vivant ici tandis qu'il est mort là-bas. Surtout, il nous fait suivre les péripéties du combat, partisans de Planck et de Bohr contre admirateurs d'Einstein. L'affrontement est si violent qu'on attend avidement chaque nouvel épisode, comme s'il s'agissait d'un film policier qui serait intitulé "le grand thriller du quantique". Aujourd'hui, alors que la théorie qui réconcilierait la relativité et la physique quantique apparaît encore comme un Graal inatteignable, il est bon de méditer sur cette épopée.'

A Review of the Spanish edition of Quantum

A review of the Spanish language edition of Quantum published today by Noticias de la Ciencia y la Techologia:

'Aunque la ciencia sigue avanzando de forma imparable, hubo una época en la que la física hizo un enorme e inesperado salto adelante. Esta era brillante se cerró durante el Quinto Congreso Solvay, en octubre de 1927, donde se reunieron 29 físicos, 17 de los cuales eran o acabarían siendo premios Nobel. Basta con observar la fotografía conmemorativa de la reunión para certificar su importancia: Schrödinger, Pauli, Heisenberg, Dirac, de Broglie, Bohr, Planck, Einstein, Curie, Lorentz... Suficiente materia gris como para cambiar el mundo.

El más famoso episodio de este congreso fue sin duda el debate entre Einstein y Bohr, dos de los mayores investigadores y teóricos de la historia, y dos científicos que ofrecían visiones no coincidentes de la realidad. Hubo otros congresos Solvay, y otros encuentros entre ambos físicos, pero ninguno como el de 1927. Sus teorías rivales fueron un estímulo brutal para ellos y para sus seguidores, que así hicieron avanzar la física de forma decisiva.

En “Quántum”, Manjit Kumar nos ofrece una amplia perspectiva histórica sobre la ciencia cuántica, y nos cuenta lo que ocurrió en Solvay y entre las personalidades que allí concurrieron. Es una historia de ciencia, pero también filosófica, de rivalidades, de personas.

El libro es una obra de divulgación científica tanto como un texto de historia y una biografía. Es así como consigue atrapar al lector, quien en sus páginas aprenderá sobre física cuántica y más aún sobre los individuos que desarrollaron la teoría, en un entorno de trabajo de principios del siglo pasado.

Por esta vía, Kumar, que es también físico, ha dado a luz un libro que se ha convertido en un auténtico éxito en Gran Bretaña y otros países. Y no es extraño, pues el producto es el fascinante relato de un debate entre dos genios, y al mismo tiempo, una obra que trata de contarnos dos visiones distintas de la naturaleza de la realidad.

Sin duda, estamos ante un libro para disfrutar desde múltiples puntos de vista. El interesado por la historia de la ciencia, el amante de la física, el lector de la filosofía moderna, el estudiante, todos encontrarán algo provocador y atractivo en él. No deben perdérselo.'

You can read an extract in Spanish here.
Translation to follow once I can convince a Spanish speaker to translate...

James Hannam reviews Quantum

James Hannam, author of God's Philosophers: How the Medieval World Laid the Foundations of Modern Science reviewed Quantum on his blog - Quodlibeta. I've taken the liberty of reproducing it below:

'Manjit Kumar’s book Quantum: Einstein, Bohr and the Great Debate about the Nature of Reality is a difficult project triumphantly accomplished. In popular history of science, the aim is to mould the history and the science together without compromising too much on either. When the science in question is quantum mechanics, an author already has his work cut out trying to explain it to the general reader. Another challenge is that the history of the quantum is about a clash of personalities and philosophical viewpoints. Turning that into a readable story is no mean feat. But Kumar has succeeded on both fronts.

The debate at the heart of Quantum is how to interpret the strange physics of the sub-atomic world. On one side was Albert Einstein. Despite the difficulty many of us have with relativity, it is actually a well-behaved physical theory that does not require us to compromise on the basic concepts of objective reality or cause and effect. Quantum mechanics, on the other hand, disposes of such foundations: it is a subjective realm where the observer appears to affect the result of experiments and where randomness is indelibly built in. Einstein could never accept this. He thought there were “hidden variables” behind quantum mechanics that would transmute it into a deterministic theory. “God does not play dice”, he said many times.

The other side of the argument was led by Niels Bohr, the greatest Dane since Tycho Brahe. Bohr developed the Copenhagen interpretation of the quantum which embraced its strangest aspects. Bohr accepted that the motion of sub-atomic particles can only be predicted as probabilities and that the experimenter is part of the same system as the thing being observed. Einstein set Bohr a number of fiendish puzzles to show that quantum mechanics was inconsistent and so incomplete. But every time, Bohr solved the problem. Eventually, after Einstein’s death, the Irish physicist John Stewart Bell developed a way to experimentally test one of the quantum paradoxes called non-locality. But, to date, the theory appears to pass even this trial.

All this has left science with a massive hangover. It is not as widely appreciated as it should be that the two crowning achievements of modern physics, relativity and quantum mechanics, are completely incompatible. It is not just that they give different results. They inhabit different metaphysical universes. Scientists have tended to assume that quantum mechanics is the more fundamental theory and string theory is an attempt, unsuccessful so far, to combine it with relativity.

I have a suspicion that current crisis in physics is a function of abandoning the metaphysical framework of a deterministic and objective universe. String theory has returned to the failed ancient Greek model of pure rationalism where clever ideas can never be tested. In the meantime, anyone who wants to understand the background to the The Trouble with Physics chronicled by Lee Smolin can do no better than to read Manjit Kumar’s Quantum.

If you haven't read James's book, check it out. It was shortlisted in 2010 for the Royal Society Science Book Prize.

'a brilliant history of quantum theory'

A review of Quantum by Paul Thomas on the Freedom in a Puritan Age website:


'Quantum mechanics is both one of the most important scientific theories of the twentieth century and one of the least understood, admittedly even by physicists themselves. Quantum theory challenges both the laws of ‘classical physics’ and throws up philosophical questions about our ability to truly understand, not just the microphysical world of the atom, but the everyday, macrophysical world which we inhabit.

In telling the story of quantum theory, Kumar has written a fascinating narrative history that interweaves scientific theory and individual biography against the background of broader historical events.

Kumar introduces us to not just the main adversaries around whom the debate over quantum theory revolves — Albert Einstein and Niels Bohr — but a supplementary cast of some of the greatest scientific minds of the twentieth-century: the conservative patriarch of modern science, Max Plank; charismatic New Zealander, Ernest Rutherford; dogmatic quantum theorists Werner Karl Heisenberg and Max Born; the ‘shy’ Paul Dirac; Wolfgang Pauli, known as “The Wrath of God” for his critical mind; the ‘scandalous’ (and sometime alley of Einstein) Erwin Schrodinger; and post-WWII Irish scientist John Bell, who came up with a famous theorem to test Einstein and Bohr’s positions. At the heart of the book though is Einstein, the most famous scientist in history, the man whose name has become a synonym for ‘genius’, and whose continued questioning of a theory he had helped initiate saw him become an increasingly isolated and discredited figure.

Quantum theory begins in 1900 with Max Planck’s discovery that the energy of light and all other forms of electromagnetic radiation could only be emitted or absorbed by matter in ‘bits’, bundled up in various sizes; ‘quantum’ being the name he gave these individual packets of energy. As Kumar says, this was a radical break from the long held belief that energy was emitted and absorbed continuously. For Planck, the quantising of energy was a pragmatic solution to another problem that he thought he would get rid of in time.

Einstein saw the revolutionary and ‘heretical’ potential of Planck’s temporary expedient. In 1905, Einstein published four papers that would eventually launch him to international stardom, including his special theory of relativity. But it was the first of these papers, in which he put forward the theory that light was made up of particle-like quanta or photons (as they were later called), that Einstein considered the most important.

In 1913, the young Bohr applied Einstein’s light-quanta theory to the electrons within an atom and their ability to emit or absorb energy; but in doing so, he violated certain tenets of accepted physics, leaving what happens within the atom completely to chance. For Einstein, it was as if one were to let go of an apple, but instead of it falling to the ground it was suspended for some unspecified length of time, before shooting off in some undetermined direction.

Nevertheless, as with Planck and his original ‘bundles’ of energy, Einstein was prepared to abandon the ‘causality’ of classical physics and tolerate random ‘probability’ for the time being, in the hope it would be removed with further scientific developments.

By the mid-1920s, however, Einstein had grown uneasy with the very probability he had introduced into the atom. It was in writing to Max Born about his theory in 1926 that Einstein expressed his growing disquiet about quantum mechanics, and in which he first uttered his famous remark that ‘God is not playing dice’. Nevertheless, he had been the unwitting inspiration for one of the greatest developments in the understanding of the quantum: Heisenberg’s uncertainty principle.

Heisenberg had discovered that quantum mechanics forbids the precise determination of both the position and the momentum of a particle at any given moment. The more accurately the one is measured, the less accurately the other can be known or predicted, as any attempt to measure an electron automatically interferes with its trajectory. As such, for the likes of Bohr, Heisenberg, and what became known as the Copenhagen school of quantum mechanics, there can be no such thing as a quantum reality free from observation. An electron simply does not exist at any place until a measurement is performed to locate it. It is the act of observation that makes ‘real’.

For Einstein, and a few like Schrodinger, there must be an objective reality free from observation and accessible to human reason. This isn’t just a scientific question, but a philosophical one. The belief that there is no such thing as an observer-free objective reality in the atomic realm affects what we can say about nature in general and, for Einstein, risks reducing science to ‘uninspired empiricism’. However, although this is ‘the great debate about the nature of reality’ to which Kumar refers, this is an argument that is never fully had-out between the main protagonists; as Bohr, unlike Einstein, is clearly not keen to step outside the uncertainty of the subatomic realm and into a real-world philosophical debate.

Amongst the strengths of Kumar’s account is placing these debates within their historical context. The uncertainty at the heart of quantum physics reflected the uncertainty of the inter-war years, which eventually saw Einstein emigrate to the United States, and brought an end to the international conferences at which these debates took place. But Kumar’s real achievement is to rehabilitate the reputation of the later-Einstein, on whose side you have no doubt Kumar is.

From the beginning Einstein argued that quantum theory was incomplete; yet as its application became increasingly successful, he became marginalised and an almost lone voice against the increasing orthodoxy of the Copenhagen Interpretation. Today, however, many physicists would agree with Einstein that quantum mechanics is an incomplete theory. As Kumar says, although Einstein never managed to deliver a decisive blow in his encounters with Bohr, his challenge was sustained and thought provoking:

“Einstein never put forward an interpretation of his own, because he was not trying to shape his philosophy to fit a physical theory. Instead he used his belief in an observer-independent reality to assess quantum mechanics and found the theory wanting.”

Kumar has written a brilliant history of quantum theory from its origins to the present; capturing, in particular, the excitement of the interwar years as the greatest scientific minds of the twentieth-century criss-crossed Europe, between conferences and university departments, meeting in train stations to snatch every opportunity to discuss the latest theories. Quantum evokes that world and takes you into those complex debates, without distracting from a fascinating story.'

Quantum - Spanish Edition

The Spanish edition of Quantum is now available online here and in bookshops throughout Spain thanks to Peter Tallack and Louisa Pritchard. Many thanks to my translator David González Raga, María Alasia and everyone else involved in its production at Kairos.

Quantum - Italian Paperback Edition

The Italian paperback of Quantum was published at the end of May and is available online here at Italian Amazon and in bookshops throughout Italy. My thanks to all those involved in its production at Mondadori by especially to my Italian translator Tullio Cannillo.

Quantum paperback published in USA and Canada

Today Quantum is published in paperback in the USA and Canada. Thanks to everyone at Norton. Love the new cover. You can buy it online here.

Quantum in paperback in French and German

Quantum is now available in French and German paperback editions and on sale, as they say, in all good bookshops in France and Germany.

You can buy the French here and the German here

Solvay 1927 - A film clip

If you want to see some extremely rare footage of some of the participants leaving the Solvay conference in October 1927. Shot by the American Irving Langmuir, its just under 3 minutes long and shows Einstein, Bohr, Schrodinger, Heisenberg, Pauli, Born, de Broglie, Dirac and others after a day discussing quantum mechanics. The commentary is provided by Nancy Thorndike Greenspan, the author of an excellent biography of Max Born called The End of the Certain World.

'An Enlightening Book on Einstein and the Quantum Theory Debate'

Jay Lehr, science director of the Heartland Institute reviews Quantum:

'While I was a student at Princeton University in the early 1950s I had a literally nodding acquaintance with Albert Einstein. During my freshman year he walked past my dormitory every day on his way to the Institute for Advanced Study. I often found myself on the sidewalk as he passed by, and we nodded to each other. I have read many an interesting biography of his life since, but none more interesting than Quantum, by Manjit Kumar.

Quantum is a biography not just of Albert Einstein’s life but also his thought processes. It also provides insight into the dozens of famous theoretical physicists who influenced and aided him in his work.

Complex Science Explained
Quantum theory, which attempts to describe the atomic and subatomic worlds, is for most people a byword for mysterious, impenetrable science. For many years it was equally baffling for the world’s most brilliant physicists. Here the author gives us a dramatic and superbly written account of this fundamental scientific revolution and the divisive debate at its core.

Simply reading Quantum may not make one an immediate expert on quantum theory, but the chronology of every great contribution to the physics of quantum theory—beginning in 1858 and continuing to the present—will be worth the price of the book.

The most complex and difficult-to-understand intricacies of quantum theory in no way reduced the joy I felt in reading this book and following the journey of so many great scientists as they researched and published their discoveries. Interestingly, these discoveries were not often verified in a laboratory, but they were agreed upon because they accorded with physical observations and allowed for reasonable mathematical solutions.

Interesting Narratives, Theories
In one of the most compelling discussions in the book, Kumar describes a conference held in Belgium in 1927. Of the 29 people invited to the conference, 17 went on to receive the Nobel Prize. At times Kumar made me feel like I was in the room. Heisenberg, Planck, Born, and Schrödinger came alive for me as I read these passages.

In an enlightening scientific discourse, Kumar explains the concept of entanglement, a quantum phenomenon in which two or more particles remain inexorably linked no matter how far apart they are. He also explains the intriguing quantum theory in which Dr. Schrodinger’s cat can be simultaneously dead and alive.

Quantum is not a book for everyone. But if you have a great deal of scientific curiosity and enjoy reading about some of the greatest scientific minds in history, you will certainly enjoy this book.'

Original review can be read here.

Edinburgh International Science Festival

A review of my talk at the Edinburgh International Science Festival by Keir Liddle of The 21st Floor:

'In front of a packed auditorium Manjit Kumar takes to the stage. Behind him is displayed an image of the “first team” of physics: Einstein, Bohr, Dirac, Planck, Curie, Schrödinger, Heisenberg and the other luminaries that attended the famous Solvay conference in 1927. Arguably the greatest minds working in the field gathered together in one place. Einstein alone being the most famous and well known physicist since Newton for his theory of relativity.

This conference was a pivotal point in quantum physics and one at which quantum theories two prize-fighters, Niels Bohr and Albert Einstein, did battle with various thought experiments to test Bohrs Copenhagen interpretation. According to this interpretation of quantum physics you can only say a particle exists when you try to measure and observe it. Einstein took exception to this as he believed that the universe did not simply go away when you did not observe it.

“I like to think that the moon is there even if I am not looking at it.”

Manjit weaved together the intriguing tale of the people who were behind the biggest discoveries in the physics of the incredibly small with an affable style and a genuine affection for the subject. Too often science and scientists can appear cold, distant and removed from human endeavour and it is valuable and important that Manjit reminded us that scientists are driven by human motivations, ambitions and that there is a very human joy in exploring and understanding the fundamental principles of the universe.'

The Meeting of Minds

I first saw the photograph of those gathered at the fifth Solvay conference, which was held in Brussels from 24 to 29 October 1927, in a biography of Albert Einstein. This was in 1979, when I was just 16. I wondered what brought these people together, and soon learned that the picture included most of the key players involved in the discovery of the quantum, and the subsequent development of quantum physics. With 17 of the 29 invited eventually earning a Nobel Prize, the conference was one of the most spectacular meetings of minds ever held.


When I was 18, I was given a print of the above photograph as a present. Many years later I began to think about it as a possible starting point for a book about the quantum. In the photograph there are nine seated in the front row. Eight men, and one woman; six have Nobel Prizes in either physics or chemistry. The woman has two, one for physics, awarded in 1903, and another for chemistry, awarded in 1911. It could only be Marie Curie. In the centre, the place of honour, sits Albert Einstein. Looking straight ahead, gripping the chair with his right hand, he seems ill at ease. Is it the winged collar and tie that are causing him discomfort, or is it what he has heard during the preceding week? At the end of the second row, on the right, is Niels Bohr, looking relaxed with a half-whimsical smile. It had been a good conference for him. Nevertheless, Bohr would be returning to Denmark disappointed that he had failed to convince Einstein to adopt his Copenhagen interpretation of what quantum mechanics revealed about the nature of reality.

Instead of yielding, Einstein had spent the week attempting to show that quantum mechanics was inconsistent, that Bohr's 'Copenhagen interpretation' was flawed. Einstein said years later that:

This theory reminds me a little of the system of delusions of an exceedingly intelligent paranoic, concocted of incoherent elements of thoughts.

It was Max Planck, sitting on Marie Curie's right, holding his hat and cigar, who discovered the quantum. In 1900 he was forced to accept that the energy of light, and all other forms of electromagnetic radiation, could only be emitted or absorbed by matter in bits, bundled up in various sizes. 'Quantum' was the name Planck gave to an individual packet of energy, with 'quanta' being the plural. The quantum of energy was a radical break with the long-established idea that energy was emitted or absorbed continuously, like water flowing from a tap. In the everyday world of the macroscopic, where the physics of Newton ruled supreme, water could drip from a tap, but energy was not exchanged in droplets of varying size. However, the atomic and subatomic level of reality was the domain of the quantum.

Bohr discovered that the energy of an electron inside an atom was 'quantised'; it could possess only certain amounts of energy and not others. The same was true of other physical properties, as the microscopic realm was found to be lumpy and discontinuous. Not some shrunken version of the large-scale world that we humans inhabit, where physical properties vary smoothly and continuously, where going from A to C means passing through B. Quantum physics, however, revealed that an electron in an atom can be in one place, and then, as if by magic, reappear in another without ever being anywhere in between, by emitting or absorbing a quantum of energy.

By the early 1920s, it had long been apparent that the advance of quantum physics on an ad hoc, piecemeal basis, had left it without solid foundations or a logical structure. Out of this state of confusion and crisis emerged a bold new theory; known as quantum mechanics, with Werner Heisenberg and Erwin Schrödinger, third and sixth from the right in the back row, leading the way. In 1927 Heisenberg made a discovery. It was so at odds with common sense that he initially struggled to grasp its significance. The uncertainty principle said that if you want to know the exact velocity of a particle, then you cannot know its exact location, and vice versa.

Bohr believed he knew how to interpret the equations of quantum mechanics; what the theory was saying about the nature of reality. Questions about cause and effect, or whether the moon exists when no one is looking at it, had been the preserve of philosophers since the time of Plato and Aristotle. However, after the emergence of quantum mechanics they were being discussed by the twentieth century's greatest physicists.

The debate that began between Einstein and Bohr at the Solvay conference in 1927, raised issues that continue to preoccupy many physicists and philosophers to this day; what is the nature of reality, and what kind of description of reality should be regarded as meaningful? 'No more profound intellectual debate has ever been conducted', claimed the scientist and novelist CP Snow. 'It is a pity that the debate, because of its nature, can't be common currency.'

When Einstein and Bohr first met in Berlin in 1920, each found an intellectual sparring partner who would, without bitterness or rancour, push and prod the other into refining and sharpening his thinking about the quantum. 'It was a heroic time,' recalled Robert Oppenheimer, who was a student in the 1920s. 'It was a period of patient work in the laboratory, of crucial experiments and daring action, of many false starts and many untenable conjectures. It was a time of earnest correspondence and hurried conferences, of debate, criticism and brilliant mathematical improvisation. For those who participated it was a time of creation.'

Planck, Einstein, Bohr, Heisenberg, Schrodinger, Born, Pauli, De Broglie, Dirac, the leading lights of the quantum revolution, are all there in that picture.

Originally posted on Nature.com

Paperback of American Edition

This is the cover of the US paperback edition to be published by Norton on 9 May 2011. My thanks to all involved in its production.

French Edition of Quantum

The cover of the forthcoming French edition. Soon I'll post a round-up of Quantum related stuff from recent months.