Quantum - reviewed in Odyssey magazine, South Africa

'Beautifully written ... a tour de force that covers the fierce debate about the foundations of reality that gripped the scientific community through the 20th century.'

Read the full review - alongside one on another Icon title, Atom - here.

Quantum - one of John Banville's Books of the Year

John Banville, who won the Man Booker prize for his novel The Sea in 2005, chooses Quantum as one of his three books of the year in Australia's The Age newspaper:

'Quantum: Einstein, Bohr and the Great Debate about the Nature of Reality (Icon Books) by Manjit Kumar is one of the best guides yet to the central conundrums of modern physics.'

Quantum - reviewed in the Daily Telegraph

'Admirably ambitious ... for those who already know at least some of the physics and want a brief, non-academic but thorough history of the subject's golden age, it is hard to beat.'

Read the full review here.

Quantum - new reprint jacket

Quantum has just recently been reprinted and we've taken the opportunity to include some of the brilliant press quotes the book has received on the new jacket - and here it is:

Quantum - an exclusive extract

Read the Prologue of Manjit Kumar's Quantum here - click on the book below to zoom in:

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Quantum - reviewed at The Book Depository

'A thrilling account of quantum theory that focusses on the central relationship between Niels Bohr and Albert Einstein'

Scroll down on this page to see the full piece.

Quantum - reviewed in the Independent

'Manjit Kumar's Quantum is a super-collider of a book, shaking together an exotic cocktail of free-thinking physicists, tracing their chaotic interactions and seeing what God-particles and black holes fly up out of the maelstrom. He provides probably the most lucid and detailed intellectual history ever written of a body of theory that makes other scientific revolutions look limp-wristed by comparison.'

Read the full review here.

Quantum - reviewed at 26.org.uk

'If you need an improving book for the autumn, with which to impress your friends and family, look no further. Manjit Kumar, who is trained as both a philosopher and a physicist, is eminently qualified to bring off this ambitious attempt to bring the story of the discovery of quantum physics to life for the layperson. He mixes up biography, narrative history and lucid explanation of the science involved to create a highly readable account of one of the most important but impenetrable topics of twentieth century thinking.'

Quantum - reviewed in the Financial Times

'Kumar is an accomplished writer who knows how to separate the excitement of the chase from the sometimes impenetrable mathematics. In Quantum he tells the story of the conflict between two of the most powerful intellects of their day: the hugely famous Einstein and the less well-known but just as brilliant Dane, Niels Bohr.'

Read the full review here.

Quantum - reviewed in the Guardian

Steven Poole reviews Quantum in today's Guardian and calls it:

'An exhaustive and brilliant account of decades of emotionally charged discovery and argument, friendship and rivalry spanning two world wars.'

Read the full review here.

Quantum - reviewed by thebookbag.co.uk

'I found Quantum a fascinating, riveting read. I have not read individual biographies of the scientists concerned beyond what can be found in customary introductory sections of popular science books, and I normally dislike the biographical approach to popular science, but in this case the interweaving of the stories of the scientists and of the science worked brilliantly. Quantum shows not only the body of science, but also its human face. I had a real feeling of observing one of the greatest revolutions of human understanding of the world as it happened; from the personalities of people involved to the administrative details of their employment to the grand sweeps of history that engulfed them. Particularly compelling was how essential for the development of ideas was the communication, co-operation and competition between the scientists: how ideas were bounced between them, reused and refashioned, and how astonishingly creative this cohort of incredibly young men became in the process. ... Quantum is a fascinating, powerful and brilliantly written book that shows one of the most important theories of modern science in the making and discusses its implications for our ideas about the fundamental nature of the world and human knowledge, while presenting intimate and insightful portraits of people who made the science. Highly recommended.'
Magda Healey

Quantum - Amazon.co.uk reader review

Amazon.co.uk customer Jenny Gardener says this (and much more) of Quantum in her review on the site, titled 'Quantum - The Human Story':

'Part social history, part popular science as well as raising questions of a philosophical nature - this makes a cracking read and comes highly recommended.'

Click the Amazon click on the right to read the full review.

Quantum - reviewed in Spiked Online

'How could anyone not believe in the importance of ‘reality’ in developing a scientific theory? The subtleties involved in that apparently simple question are what make the debate between Bohr and Einstein so fascinating and of such importance, a debate expertly told and analysed in a new book by Manjit Kumar. At stake, he argues, were the soul of physics and the nature of reality.'

Read the full review here.

Quantum - reviewed in Scotland on Sunday

'An elegantly written and accessible guide to quantum physics, in which Kumar structures the narrative history around the clash between Einstein and Bohr, and the anxiety that quantum theory "disproved the existence of reality".'

Einstein & Bohr after Solvay 1930

Quantum Lives 6: Erwin Schrodinger

Erwin Schrödinger (1887–1961) spent the Second World War at a safe haven provided by the Irish Prime Minister Eamon de Valera. A keen amateur mathematician, de Valera brought forward the establishment of the Institute for Advanced Studies in Dublin and appointed Schrödinger to a professorship. The seventeen years he spent in the Irish capital proved to be among the happiest years of his life as he devoted himself increasingly to philosophical questions surrounding the foundations of physics and the relationship between the physical and biological sciences. It was during this period that Schrödinger wrote one of the most famous and influential books of twentieth century science, What is Life? His belief that the essential nature of living organisms could be studied and understood in terms of physical principles convinced some of the brightest young minds to swap physics for the new field of molecular biology. Schrödinger led an unconventional personal life that included sharing a home with his wife and mistress. In March 1956, aged 69, Schrödinger returned to Vienna as professor of theoretical physics. Walter Moore (1989) Schrödinger: Life and Thought is a fascinating tale of a complex man: a scientist, a serial womanizer, and an enthusiastic explorer of Eastern mysticism.

Solvay 1911

Quantum Quotes 4

‘Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the “old one”. I, at any rate, am convinced that He is not playing at dice.’

Albert Einstein

Quantum Lives 5: Werner Heisenberg

Werner Heisenberg (1901–1976) was placed in charge of the German atomic bomb project during the Second World War and became the physicist most feared by allied scientists. In September 1941 Heisenberg visited Bohr in German-occupied Denmark. One evening they went for a stroll in the park next to the institute. It was like old times, but instead of quantum physics Heisenberg raised the possibility of constructing an atomic bomb. Neither man agreed later on who said what. Was Heisenberg trying to open a channel of communication or was he trying to elicit information about the status of the allied atomic bomb? Whatever the truth of the matter, it has been the subject of speculation ever since and forms the basis of Michael Frayn’s play Copenhagen, their friendship effectively ended that day. After the war, Heisenberg was arrested and interned in a secluded farmhouse in Britain for six months with other leading members of the Germany’s atom bomb programme. David C. Cassidy (1992) Uncertainty: The Life and Science of Werner Heisenberg is the definitive biography that charts the highs and lows in the life of this flawed genius. Cassidy reconstructs Heisenberg’s role in the German atomic bomb project and the ill-conceived visit to see Bohr. Although highly respected and regarded as one of the greatest theorists of the twentieth century, Cassidy’s majestic work reveals exactly why Heisenberg never enjoyed the same degree of affection from his colleagues as Pauli despite lacking his friend’s bite. After the war and Planck’s death, Heisenberg became a leading spokesman for German science.

Quantum Lives 4: Wolfgang Pauli

Wolfgang Pauli (1900–1958) married Käthe Deppner, a twenty-three year-old dancer and actress, in December 1929. The marriage ended within a year. The fact that she left him for a chemist particularly rankled Pauli: ‘Had she taken a bullfighter I would have understood,’ he said, ‘but an ordinary chemist?’ Pauli began to drink heavily and at the behest of his father sought the help of the celebrated psychoanalyst Carl Jung. Initially placing him in the care of a young assistant, Jung later analyzed some four hundred of Pauli’s dreams and the pair remained in touch for a quarter of a century. In September 1931, Pauli wrote: ‘With women and me things don’t work out at all, and probably it also will never succeed again. This, I am afraid, I have to live with, but it is not always easy. I am somewhat afraid that in getting older I will feel increasingly lonely. The eternal soliloquy is so tiresome.’ Three years later he remarried and this time the union lasted until his death.
If his life fell apart together with his first marriage, Pauli’s physics did not. In 1930 he made the first tentative suggestion that there existed an undiscovered particle that was emitted during the loss of a beta particle by a radioactive nucleus. Pauli’s hypothetical particle had to have no charge and almost no mass; he later described it as ‘that foolish child of the crisis of my life’. Christened the neutrino, Pauli lived long enough to see its experimental confirmation in 1956. As he lay dying in hospital, Pauli was asked if there was someone he would like to talk with. Niels Bohr came the reply. Charles P. Enz (2002) No Time to be Brief: A scientific biography of Wolfgang Pauli contains plenty of biographical material, but its intended readership is one with a physics background. Chapter 11, Abraham Pais (2000) The Genius of Science: A portrait gallery of twentieth-century physicists is a warm, insightful, and highly readable recollection of the man and his science by an admirer who knew him well.

Quantum Lives 3: Max Born

Max Born (1882–1970) spent seventeen years, from 1936 to 1953, as the Tait professor of natural philosophy at Edinburgh University quietly teaching undergraduates and supervising graduate students. Max Born (2005) The Born-Einstein Letters 1916-1955: Friendship, Politics and Physics in Uncertain Times with a commentary by Born offers a rare glimpse into the personal, scientific, and social concerns of two men as the events of the most tumultuous years of the twentieth century unfolded. When in 1953 Born retired and returned to Germany to live in a small spa town near Göttingen, Einstein wrote to him: ‘If anyone can be held responsible for the fact that you are migrating back to the land of the mass-murderers of our kinsmen, it is certainly your adopted fatherland – universally notorious for its parsimony.’ The restoration of confiscated property and his pension by the Federal German government made Born’s homecoming all the more attractive. In the last decade of his life, he became increasing active in discussions surrounding the social responsibilities of scientists and in July 1955 signed a declaration condemning the development of atomic weapons. Written for his own family rather than for publication, Born (1978) My Life: Recollections of a Nobel Laureate is a vivid account of his life until the outbreak of the Second World War. Nancy Thorndike Greenspan (2005) The End of The Certain World: The Life and Science of Max Born is a sensitive and astute portrait of a man later overshadowed by his more famous colleagues.

Oppenheimer on The Golden Age of the Quantum

'Our understanding of atomic physics, of what we call the quantum theory of atomic systems, had its origins at the turn of the century and its great synthesis and resolutions in the 1920s.It was a heroic time. It was not the doing of any one man. It involved the collaboration of scores of scientists from many different lands, though from first to last the deeply creative and subtle and critical spirit of Niels Bohr guided, restrained, deepened, and finally transmuted the enterprise. 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. There was terror as well as exaltation in their new insight.'

Robert Oppenheimer

Solvay 1930: Einstein & Bohr

Solvay 1927

This photograph of those gathered at the fifth Solvay conference on ‘Electrons and Photons’, held in Brussels from 24 to 29 October 1927, encapsulates the story of the most dramatic period in the history of physics. With seventeen of the twenty-nine invited eventually earning a Nobel Prize, the conference was one of the most spectacular meetings of minds ever held. It marked the end of a golden age of physics, an era of scientific creativity unparalleled since the scientific revolution in the seventeenth century led by Galileo and Newton.

Eight men and one woman are seated in the front row, six have Nobel Prizes in either physics or chemistry. The woman has two, one for physics awarded in 1903 and another for chemistry in 1911. Her name: Marie Curie. It was Max Planck, sitting on Curie's right, holding his hat and cigar, who discovered the quantum.

In the centre, the place of honour, sits another Nobel laureate, the most celebrated scientist since the age of Newton: 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 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’.

C.P. Snow on the Einstein-Bohr Debate

'The arguments on both sides are most beautiful and subtle....No more profound intellectual debate has ever been conducted - and, since they were both men of the loftiest spirit, it was conducted with noble feeling on both sides. If two men are going to disagree, on the subject of most ultimate concern to them both, then that is the way to do it. It is a pity that the debate, because of its nature, can't be common currency.'

C.P. Snow in Variety of Men: Statesmen, scientists, writers

Quantum Quotes 3

‘For those who are not shocked when they first come across quantum theory cannot possibly have understood it.’

Niels Bohr

Quantum Quotes 2

‘It was as if the grounds had been pulled out from under one with no firm foundation to be seen anywhere, upon which one could have built.’

Albert Einstein

Quantum Quotes 1

‘Briefly summarized, what I did can be described as simply an act of desperation.’

Max Planck

Quantum Lives 2: Niels Bohr & Ernest Rutherford

Niels Bohr (1885–1962) had six sons. The eldest, Christian, was only seventeen when in July 1934 he drowned in a sailing accident. Bohr had to be restrained by his friends from attempting an impossible rescue. His fourth son, Aage, succeeded him as director of the institute and received the Noble Prize for physics in 1972 for his work in nuclear physics. Niels Bohr was a father figure to many who passed through the doors of his institute. Some of the most famous explained Bohr’s contributions to physics and recollected their experiences of working with him in Stefan Rozental (1967) Niels Bohr: His Life and Work as seen by his Friends and Colleagues. A.P. French and P.J. Kennedy (1985) Niels Bohr: A Centenary is another highly readable collection essays that covers various periods and aspects of Bohr’s life from his work on the quantum atom to his later contributions to nuclear physics, from his political influence to his stance on nuclear weapons. Ruth Moore (1966) Niels Bohr: The Man, His Science, and The World They Changed and Niels Blaedel (1985) Harmony and Unity: The Life of Niels Bohr are both excellent introductions to the life and work of the great Dane. The definitive biography is Abraham Pais (1991) Niels Bohr’s Times, in Physics, Philosophy, and Polity. A less mathematical treatment than his acclaimed scientific biography of Einstein, Pais manages to reveal the man while tracing in detail Bohr’s impact on physics.


Ernest Rutherford (1871-1937) was Bohr’s role model. When he heard the news that Rutherford had died, Bohr was at a conference in Bologna, Italy. The following day, in tears, Bohr made the announcement and honoured Rutherford as he delivered a moving tribute to his mentor. David Wilson (1983) Rutherford: Simple Genius is the story of a remarkable life that began in a small, single-storey wooden house in New Zealand and ended on the other side of the world in a resting place near Isaac Newton in Westminster Abbey as Lord Rutherford of Nelson. The father of nuclear physics, whose greatest achievements came after he won the 1908 Nobel Prize for chemistry for his investigations into the disintegration of the elements and the chemistry of radioactive substances, Rutherford hoped ‘that no one discovers how to release the intrinsic energy of radium until man has learned to live in peace with his neighbour.’

Quantum Lives 1: Max Planck & Albert Einstein

These mini-biographies of some of the key protagonists in Quantum didn't quite make it into the book itself, but we'll post them here over the next few weeks. First up are Max Planck and Albert Einstein:

Max Planck (1858–1947) John L. Heilbron (2000), The Dilemmas of An Upright Man describes Planck’s rise to the pinnacle of German science and examines how he reconciled his sense of duty to his country and to physics once confronted by the realities of the First World War and the Third Reich. Heilbron’s absorbing study reveals how Planck tried to defend the interests of German science and therefore had no option but to negotiate with the Nazis. Planck made his compromises, gaining little but surrendering much.

Albert Einstein (1879–1955) has been the subject of countless books. Denis Brian (1996), Einstein: A Life, Albrecht Fölsing (1997), Albert Einstein: A Biography, and Walter Isaacson (2007), Einstein: His Life and Universe are all fine portraits of a man who was not the secular saint of popular myth. Abraham Pais (1982), ‘Subtle is the Lord …’: The Science and the Life of Albert Einstein is a scientific biography that offers a more mathematically detailed presentation of Einstein’s physics. Dennis Overbye (2001), Einstein in Love is an enthralling account of the life and times of the young Einstein that ends in 1920 and the first meeting with Bohr. Thomas Levenson (2003), Einstein in Berlin recounts the eighteen years he spent in the German capital until Hitler’s rise to power in January 1933. Levenson captures a vibrant, decadent metropolis in a time of change and unrest that flourished as a cultural melting-pot which produced an all-too-brief flowering in art, architecture, music, cinema and theatre, but whose brightest star was Einstein. ‘I simply enjoy giving more than receiving in every respect, do not take myself nor the doings of the masses seriously, am not ashamed of my weaknesses and vices, and naturally take things as they come with equanimity and humour. Many people are like this, and I really cannot understand why I have been made into a kind of idol’, Einstein wrote to Max Born in April 1949.

Quantum by Manjit Kumar - Published 16th October 2008

For most people, quantum theory is a byword for mysterious, impenetrable science. And yet for many years it was equally baffling for scientists themselves. In this magisterial book, Manjit Kumar gives a dramatic and superbly-written history of this fundamental scientific revolution, and the divisive debate at its core.

Quantum theory looks at the very building blocks of our world, the particles and processes without which it could not exist. Yet for 60 years most physicists believed that quantum theory denied the very existence of reality itself.

In this tour de force of science history, Manjit Kumar shows how the golden age of physics ignited the greatest intellectual debate of the twentieth century.

Quantum theory is weird. In 1905 Albert Einstein suggested that light was a particle, not a wave, defying a century of experiments. Werner Heisenberg’s uncertainty principle and Erwin Schrödinger’s famous dead-and-alive cat are similarly strange. As Niels Bohr said, if you weren’t shocked by quantum theory, you didn’t really understand it.

While Quantum sets the science in the context of the great upheavals of the modern age, Kumar’s centrepiece is the conflict between Einstein and Bohr over the nature of reality and the soul of science. ‘Bohr brainwashed a whole generation of physicists into believing that the problem had been solved’, lamented the Nobel Prize-winning physicist Murray Gell-Mann. But in Quantum, Kumar brings Einstein back to the centre of the quantum debate.

Quantum is the essential read for anyone fascinated by this complex and thrilling story and by the band of brilliant men at its heart.

Manjit Kumar has degrees in physics and philosophy. He was the founding editor of Prometheus, an interdisciplinary journal that covered the arts and sciences, and is the co-author of Science and the Retreat from Reason, which introduced key areas of modern science while defending notions of social progress and scientific advance.

Published in 1995, it was critically acclaimed as a ‘corrective to the hype’, ‘thought-provoking’, and ‘undoubtedly one of the best introductions one can find to the crisis of confidence within science itself’.

He has written and reviewed for various publications including The Guardian, the Times Literary Supplement, and the Irish Times. He lives in north London with his wife and two sons.