"Uncertainty" by David Lindley

This is the best account of the history of the development of quantum physics that I have read. 

The story of how Heisenberg came up with his uncertainty principle, charting the demise of determinism in physics, from the prehistory of Brownian motion, through the first stirrings of radioactivity and quantum physics by Becquerel and Rutherford and Planck and Einstein, through the Bohr model of the atom to the alternative versions of quantum mechanics proposed by Heisenberg and Schrodinger. Having taught physics for 34 years, I was familiar with the concepts and much of this history but this book (written by an old house mate of mine from student days) is a hugely lucid account of how a remarkably small group of people constructed some revolutionary and philosophically difficult theories. It clearly shows their contributions and explores the human side of their interactions, as well as giving due credit to some of the other key players with whose names we are less familiar today, such as Eastbourne's own Frederick Soddy, de Broglie, Born and Bohm, Compton and Pauli and Sommerfield. It also shows what a ridiculous own goal Hitler scored when he expelled key 'non-Aryan' scientists, hugely impoverishing German science; an own goal the Brexiteers seem determined to want to repeat.

Selected quotes:

• "Dead particles of dust clearly couldn't move of their own volition, nor was any external influence pushing them around. Yet move they all too plainly did. ... Faced with this impossible dilemma, science took the prudent course and ignored Brownian motion for decades." (Ch 1) Brown's book about this is mentioned in Middlemarch!
• "Because he developed in Munich a lifelong habit of staying out late at bars and cafes, Pauli generally missed morning lectures." (Ch 6)
• "Heisenberg had ... depicted the electron's physical presence as a combination of things it might be doing, rather than some specific indication of where it was." (Ch 11)
• "In his crazed desire to promote Aryan culture and safeguard Germany from noxious foreign influences, Hitler succeeded in the space of just a few years in destroying Germany's preeminent position in physics." (Ch 14)
• "Schools of science, as of art or music, rarely stay for long in one place." (Ch 15)
• "Spengler's method is to lay out reams of detail and weighty quantities of obscure facts, and then, as the reader's head begins to nod, to leap adroitly to grand assertions about what it all must mean." (Ch 15) I have noticed a similar technique with writers in the earth-mysteries genre such as von Daniken: they 'leap adroitly to grand assertions about what it all means' having puzzled the reader with perplexing mysteries; I call this the 'wow-thus' argument. But it's not much different in philosophy; some philosophers spend 90% of their books using detailed and sometimes nit-picking scrutiny to demolish each system of their opponents undermining all of the reader's previous beliefs, until the reader is desperate for some sort of ground on which to stand, at which point they rush out their own, virtually unexamined, grand system. 
• "Uncertainty did not erupt capriciously in the mid-1920s. It had been welling up for a decade or more already by then, forcing itself upon the reluctant consciousness of scientists." (Ch 15)
• "In the rise of uncertainty in Germany ... there's an irreducible element of contingency ... In this respect scientific history is like history in general." (Ch 15)
• "For most philosophers, though, loosey-goosey won't do." (Ch 17)

This is the best account of the history of quantum physics I have read. It is one of the books on which Benjamin Labatut based his misleading collection of fictionalised biographies 'When we cease to understand the world'. Readers interested in this topic would be well advised to read Philip Ball's Beyond Weird which provides an update into the concepts which is as understandable as I have ever found a book about this difficult topic. 

Other books on Science and Scientists which are reviewed in this blog may be found on this page.

November 2022; 222 pages

This review was written by the author of Bally and Bro, Motherdarling  and The Kids of God

"Beyond Weird" by Philip Ball

This book is about quantum physics. It contains all the usual suspects: wave-particle duality, the Heisenberg Uncertainty Principle, Schrodinger's Cat, the Many Worlds Interpretation. According to Ball these are fundamentally inadequate attempts to view the quantum world - which underpins (and is coherent with) the everyday world - in images that rely on everyday understandings. He throws in some of the modern research on entanglement, superposition, wavefunction collapse and decoherence. And, in the end, he concludes that possibly, quantum physics is a theory of information.

It is a comprehensive overview of the field and, so far as I can judge, it is fair to all the many different interpretations of what quantum physics means. It even asks whether the theory is ontic (dealing with reality) or epistemic (dealing with what we know). I found it tough going in places and there are some bits that I still don't understand (and I used to teach quantum physics at secondary school level). But there were other moments when Ball's explanations led me a significantly deeper understanding than I had before and for that I can only be grateful. And impressed. If he can deliver even a little greater understanding about this tough subject, it is a remarkable achievement.

Selected quotes:

• “Quantum theory ... is a theory about information. ... it asks what a theory of knowability can look like.” (p16)
• “What do we mean by ‘is’? ... As for what an electron ‘is’, all we can talk about for sure is what we can see and measure.” (p60)
• “Everything that seems strange about quantum mechanics comes down to measurement. If we take a look, the quantum system behaves one way. If we don’t, the system does something else.” (p78)
• “Niels Bohr ... wasn’t naturally gifted as a writer - he would draft and redraft endlessly without much obvious benefit to the prose.” (p104)
• "Whatever the question, the answer is ‘Yes’ (unless it’s ‘No’)" (chapter heading)
• “Quantum mechanics might seem ‘weird’, but it is not illogical. It’s just that it employed a new and unfamiliar logic ... with different customs and traditions and with its own beautiful internal consistency.” (p128)
• “It is not obvious why any of the properties that things have at the everyday scale should remain meaningful properties at the microscopic scale. Some don’t. Electrons don’t have a colour.” (p129)
• “No one fully understands how quantum computers work.” (p278)
• “In science ... it’s as worthwhile for an idea to be productive as it is for it to be ‘right’.” (p285)
• “Might it be that non-locality is simply in the nature of things, and relativity is the only thing that limits its influence?” (p309)
• “There’s no guarantee that the world’s innermost workings will fit a language developed mostly to conduct trade, courtship and banter.” (p324)

October 2022; 354 pages

Other books reviewed in this blog about science and scientists can be found here. 

This review was written by the author of Motherdarling  and The Kids of God

"Seven brief lessons on Physics" by Carlo Ravelli

This was the last book read by my dad before he died. He was an electronics engineer all his life. He worked on radar during World War II. Later he worked on the very first computers, meeting Alan Turing and Norbert Weiner. After that he researched radiocarbon dating, discovering that a fragment of wood found on Mount Ararat wasn't old enough to come from the Ark, and finally he worked as part of the team that created radio-controlled clocks.

In fewer than 80 pages, Rovelli talks about General Relativity, Quantum Physics, Cosmology, Particle Physics, Loop Quantum Physics, Thermodynamics and the nature of time, and Ourselves; I have taught Physics for 33 years and I have been a human for even longer and yet I still, repeatedly, learned fascinating things from this brilliant book. Plus it is superbly written and it tells so eloquently of the joys and challenges of being a scientist.

Just some of the brilliant insights from this wonderful little book.

• "the gravitational field is not diffused through space; the gravitational field is that space itself." (p 6) This is a triumph of Descartes over Newton: a vortex space rather than one filled with action-at-a-distance. Space undulates. :
• light curves round heavy objects
• time goes more quickly at altitude
• black holes exist
• "space cannot stand still; it must be expanding" (p 8)
• "space moves like the surface of the sea" (p 9)
• "Why does the periodic table have this particular structure, with these periods, and with the elements having these particular properties? The answer is that each element corresponds to one solution of the main equation of quantum mechanics." (p 15)
• "an electron is a series of jumps from one interaction to another. When nothing disturbs it, it is not in any particular place. It is not in a 'place' at all." (p 15)
• Loop Quantum Gravity proposes that space is quantised in very small linked rings: "Space is created by the linking of these individual quanta of gravity" (p 41) 
• "The passage of time ... is born in the world itself in the relationship between the quantum events that comprise the world and are themselves the source of time." (p 42). 
• "Our universe may have been born from a bounce in a prior phase, passing through an intermediate stage in which there was neither space nor time." (p 47)
• "How the gravitational field behaves when it heats up is still an unsolved problem. ... when heat is diffused to the gravitational field, time and space themselves must vibrate ... what is a vibrating time?" (p 56)
• "There is a detectable difference between the past and the future only when there is flow of heat. Heat is linked to probability; and probability in turn is linked to the fact that our interactions with the rest of the world do not register the fine details of reality ... due to the limitations of our consciousness we only perceive a blurred vision of the world, and live in time." (p 60)
• "The heat of black holes is a quantum effect upon an object, the black hole, which is gravitational in nature. ... The heat of black holes is like a Rosetta Stone of physics, written in a combination of three languages - Quantum, Gravitational and Thermodynamic - still awaiting decipherment in order to reveal the true nature of time." (p 62)
• "We are like an only child who on growing up realizes that the world does not revolve around them alone, as they thought when little. They must learn to be one among others. Mirrored by others, and by other things, we learn who we are." (p 65)
• "All things are continually interacting with each other, and in doing so each bears the traces of that with which it has interacted: and in this sense all things continuously exchange information about each other." (p 68)
• "It would be absurd to ask whether 'I' can do something different from what the whole complex of my neurons has decided: the two things ... are the same." (p 71)
• "Our reality is tears and laughter, gratitude and altruism, loyalty and betrayal, the past which haunts us and serenity." (p 74)
• "We are nature, in one of its innumerable and infinitely variable expressions." (p 74)
• 
  
• "And to the very last: doubt." (p 19)

What a way for my dad to end his reading career.

Magnificent. July 2017, 79 pages

"The Strangest Man" by Graham Farmelo

This is the biography of Paul Dirac, the mathematical physicist whose work, with Heisenberg laid the theoretical foundations of quantum theory, who synthesised quantum physics and special relativity to develop quantum electrodynamics, and who predicted the positron and anti-matter. He shared the Nobel Prize with Schrodinger and was, at the time, the youngest recipient of the Physics prize.

He was famously taciturn; so much so that fellow students invented a unit called the dirac to represent the smallest imaginable amount of conversation, one word per hour.

He was also famously scruffily dressed. I used to cite him as an example whenever people came up with the dictum "Dress smart, think smart."

I was inspired to read this book having read the brilliant The Fly in the Cathedral by Brian Cathcart which explores the background to Cockcroft and Walton splitting the atom. The Strangest Man is a stunning biography. Not only does Farmelo manages to make quantum physics accessible, at least in its generalities; not only does he describes the intoxicating excitement of the early days of discovery with Heisenberg and Einstein and Schrodinger, when Gottingen University was one pole and Bohr's Copenhagen the other; but he also charts the dreadful consequences of the Second World War, when Schrodinger had to hide in Dublin having initially endorsed Nazism, when Dirac's best friend Kapitza was kept in Moscow by Stalin, always fearing that Beria might arrest him and have him killed, when Heisenberg was working for the Nazis and Bohr was in occupied Denmark, and Dirac's sister, an Englishwoman married to a Jew, was in occupied Amsterdam. Then there are the days of McCarthyism when Dirac's left wing politics had him banned from America while his friend Oppenheimer, who had led the atom bomb project, had his security clearance revoked.

And in particular, this biography centred on the human that was Dirac, the survivor of a horrible childhood in which his life and that of his mother who became a slave in her own home and Dirac's brother who killed himself, and Dirac's sister who gave up on life to stay quietly at home until Dirac managed to free her to go to University were all the victims of a terrible father, a bully, an adulterer, a tax cheat, and a man who tried in vain to understand the difficult stuff that his brilliant son was doing.

Then comes Dirac's marriage to a lively tempestuous woman, the polar opposite of the taciturn man he himself was. He acquired two step-children (his step-daughter disappeared in America, her car found abandoned) and fathered two children of his own. His marriage had its rocky patches. They were too different. And he must have struggled not to be like his own father. But the marriage survived.

This was a stunning portrait of a brilliant mind. Read it!

August 2016; 438 pages

There is a BBC Radio 4 In Our Time programme about Paul Dirac; it was broadcast on 5th March 2020

In detail:

Dirac had a dreadful childhood. His father was a disciplinarian teacher who bullied his family. Paul was made to eat dinner with his father and to speak only French (his father was Swiss); he was often sick. Paul's elder brother Felix committed suicide (which devastated the father so he was loving if a bully); his sister stayed at home after being schooled and did nothing; the mother became an unpaid servant for the father, kept on a pittance (although he was clearly a lot richer than he admitted) and was told by him after thirty years of marriage that he had never loved her; she then discovered he had been having at least one long term affair. In short, the father was a nasty piece of work.

Paul was forced to study engineering at Bristol University; he was two years younger than the other students; having graduated Bristol arranged for him to take a maths degree and skip the first year. But he almost never got to Cambridge because his father was unwilling to find the necessary money for Paul to afford to live. It was only once he got to Cambridge as a graduate student that he started to fill in some of the huge holes in his knowledge, partly by taking extra geometry classes on Sunday afternoon in the Arts School when, apart from him and the other students having tea and being taught, and a few cleaners, the building was "as lifeless as a museum at midnight". (p 72)

He cultivated a straight-talking, straight-writing, plain English prose style following George Orwell's dictum that "Good prose is like a windowpane." (p 75)

Even Dirac was subject to failing to see when he was on the trail of something. When he first met de Broglie's idea that a particle such as an electron could act like a wave he "carried out some initial calculations but put the work aside after concluding that he had done nothing worth publishing. Having sniffed the scent of an important problem, he had then lost it; but he would soon return." (p 81)

His first breakthrough was recognising that the rather complex maths in Heisenberg's first formulations of quantum theory, being non-commutative, reminded him of Poisson's brackets: "Fifty two years later, he remembered, 'The idea first came in a flash, I suppose, and provided of course some excitement'" (p 86) Brackets were important to Dirac. Having invented a new mathematical notation for quantum physics which involved two halves of a bracket (which he called the bra and the ket) he later told a discussion at high table in St John;s on neologisms that "I invented the bra". Being taciturn he then relapsed into silence for the rest of the meal. (p 326)

When Oppenheimer was having a nervous breakdown at the Cavendish he tried to poison his teacher, Blackett, by leaving him an apple laced with chemicals. (p 97) Shades of Snow White and Alan Turing! When he defended his PhD thesis to examiners Franck and Born Franck later said: "I'm glad that is over. He was on the point of questioning me." (p 133)

Even Albert Einstein struggled "to understand his [Dirac's] peculiar combination of logic and intuition" telling a friend "This balancing on the dizzying path between genius and madness is awful." (p 114)

He hypothesised the positron (which he called an anti-electron; a later suggestion from California was 'oreston' because Electra's brother was Orestes) because he "followed the logic of Sherlock Holmes: 'When you have eliminated all which is impossible then whatever remains, however improbably, must be the truth.'" (p 187) (Doyle 1926, The Adventure of the Blanched Soldier). We are still in a world where the imbalance of matter over anti-matter of just one part in a billion after the Big Bang cannot really be explained but "without that imbalance, the matter and anti-matter formed at the beginning of time would have annihilated each other immediately, so that the entire universe would only ever have amounted to a brief bath of high-energy light. Matter would, in that case, never have had an opportunity to discover anti-matter." (p 434)

Farmelo quotes Stephen Spender talking about young Germans after the great inflation: "their aims were to live from day to day; and to enjoy to the utmost everything that was free: sun, water, friendship, their bodies." (p 121)

The big band (OK, that's a typo, but it sounds so much better than the big bang) theory of the universe was first proposed by a Belgian cleric, the Abbe Lemaitre "who believed that the Bible teaches not science but the way to salvation" (p 261)

Despite a long bachelorhood lasting beyond thirty, Dirac flirted with Gamow's wife Rho and later got involved with Wigner's sister, Hungarian born Manci, who became his wife (although he described her as "Wigner's sister" even after the wedding. They had a long courtship conducted often by letter. When she complained he didn't answer her questions he numbered her letters and wrote a table of (often brutally) honest responses leading her to complain that some of the questions he had now answered were rhetorical! (p 262) As he grew closer to marriage his parents' relationship fell apart. His father told his mother he had not loved her for thirty years (predating Dirac's birth) and his mother discovered that his father had been engaging in long-term affairs (after he died she also discovered that he had been systematically cheating the taxman so he wasn't just miserly with her). But Dirac's marriage to Manci, though often tempestuous (at least on her part, he greeted her moods with indifference which must have infuriated her even more) did last. "She once snapped at him when he was eating his dinner, 'What would you do if I left you?' only for him to reply - after a half-minute pause - 'I'd say "Goodbye dear"'" (p 366)There is a photo of him on the beach at Brighton on his honeymoon in his suit "pencils still protruding from the pocket of his jacket" (p 284)

He was intrigued by the coincidental ratios of force strengths to one another and to the dimensions of the Universe and hypothesised that this might be because the strength of gravity is inversely proportional to the age of the Universe (which would explain why it is expanding but rather upsets the standard estimates of such things as the age of the Earth). (p 290)

He became Fred Hoyle's supervisor "partly because he was amused at the prospect of a relationship between a supervisor who did not want a student and a student who did not want a supervisor" (p 295)

He disliked the idea of electrons as point sources because that would involve infinities in such things as electric field strengths. But I would have thought that quantum mechanics does not allow points; they are forbidden by Heisenberg; a particle that was a point would have an infinite momentum,

He believed mathematical beauty was more important than experimental evidence.

As he got older he was more often challenged by "the drawn sword of youth". (p 321) As Oscar Wilde said in 1887 "In America, the young are always ready to give those who are older than themselves the full benefit of their inexperience." (p 332)

During the Second World War he worked on the separation of the fissile U-235 isotope from its chemically identical and much more abundant non-fissile U-238; he invented a series of methods including centrifuges. (p 321)

After Einstein's death, Dirac became "the most famous loner in theoretical physics, an elderly rebel with a cause that no one else could quite understand." (p 355) He then developed a primitive version of string theory.

Page references refer to the 2010 Faber and Faber paperback edition

"Life on the Edge" by Jim Al-Khalili and Johnjoe McFadden

This book is about Quantum Biology.

The essential thesis of this work is that life is too ordered to have developed by chance from the random fluctuations of thermodynamics. Each living cell requires the coordination of a number of organelles; even the molecules of RNA which might have formed the first replicating molecules are highly complex and ordered. Enzyme processes which are the fundamental processes of life are carefully structured, although the language that this book uses (the enzymes unzip, cut, select etc) tends to prejudice one's thinking towards assigning a purposeness which the enzymes may not possess. Instead of thermodynamics, the authors propose that life requires the more ordered processes of quantum physics.

The two effects they believe are most useful to life are quantum tunnelling and quantum entanglement. Quantum tunnelling makes use of the wave nature of particles; since the particle wave means that the particle is delocalised in space it has a possibility that it is on the far side of an energy barrier so that it can react even when the energetics suggest it won't. The delocalisation also makes possible 'quantum search': instead of randomly trying out one combination after another you can explore all possibilities at the same time.

But the problem with quantum effects is that they are on a very very small scale and that the waviness feature can be disrupted by 'measurement' which in practice means interaction with another particle. Given how busy and crowded and hot the inside of a cell is, it seems surprising that there isn't a permanent state of decoherence. But these authors suggest that the cell uses tricks to ensure coherence for long enough for the necessary actions for life can take place; in one occasion they suggest that this takes place by a synchronising of oscillations within the cell which is the same thing as is suggested by Stephen Strogatz in Sync.

This is a serious scientific book and they provide great evidence for what they are suggesting. But at the end I was unsure how important it all was. There are electrons and protons inside the molecules that make up cells and these very tiny particles inhabit the quantum universe and follow quantum rules. So it is surely inevitable that the chemical reactions that make and are used by enzymes utilise quantum mechanics, after all, chemistry is all about electron transfer. There surely is no dispute about this. I think what they are suggesting is that the fact that quantum physics underpins the chemistry means that the odds on the spontaneous generation of life are much better than they first appear.

OK. It is obviously harder than we first thought to create life. Even the simplest organisms we know have extraordinarily complex internal structures. If it is too difficult to create complex molecules by random reactions then we are left with the possibility that life wasn't generated in the early history of this planet but was either created or arrived from elsewhere (although this still begs the question of how it arose elsewhere). But if quantum effects makes it too easy to create complex molecules than why was life apparently only created once? (These authors seem to suggest that the complex molecules somehow competed and only one life form remained after natural selection had taken place but if it really is that easy to create complex molecules why has this process only happened when the earth was very young?) In the end you have to assume that there is only one type of life that is viable but that it is relatively easy to spontaneously generate this form. After all, astrobiologists tell us that there are very few elements which have the appropriate reactions so that it is almost certain that only carbon-based life forms can exist in this universe.

This was an incredibly well-written book with lots of lovely asides (mostly about the bizarre life histories of the scientists mentioned) and it explains some really difficult stuff superbly well. I am not sure to what extent I was convinced by the thesis but it was great fun reading it.

May 2016; 433 pages

"The Structure of Scientific Revolutions" by Thomas Kuhn

I first read this book, which was published in 1962, when I was studying the History and Philosophy of Science at Cambridge in 1987-8. It was a revolutionary thesis. This is the third edition (1996) which adds a postscript to respond to some of the issues that its original publication raised.

Science, Kuhn suggests, does not make steady progress closer and closer to the truth. Rather, it is oscillates between a 'normal' phase during which scientists solve problems and a 'revolutionary' phase when scientific certainties are thrown out of the window and a radically different understanding is born.

He calls the framework within which normal science is done a 'paradigm' and the revolution a 'paradigm shift'. There are many similarities between the way science develops during a paradigm shift and the way students learn if we assume the 'threshold concepts' theory of learning.

For example, In the 1880s physicists were complacently expecting that soon their classical models would be able to explain all that needed to be explained. They were refining them and making them a little more accurate. There were a few clouds on the horizon. Maxwell's equations suggested that light was an electromagnetic wave but no one could detect the 'aether', the postulated medium through which the e-m waves must ripple. The 'ultra-violet catastrophe' was the theoretical model of the atom which predicted that when you heated something up it should glow purple before it glowed red and at some stage it would radiate infinite amounts of energy in the ultra-violet part of the spectrum. And the photo-electric effect was an experiment which suggested that the energy of the electrons emitted from a surface when light was shone on it was not linked to the brightness of the incoming light. But these were blips and no-one seriously doubted that classical physics would soon be able to solve these problems.

In fact the failure to detect the aether was explained once Einstein had discovered his theory of Special Relativity with its bizarre claims that the speed of light was the fastest possible speed, the simultaneity was relative, that time slowed down as you got faster and that mass and energy were inter-convertible. The ultra-violet catastrophe gave rise to the weird world of Quantum Physics and the photoelectric effect was the key evidence for wave-particle duality which shortly led to de Broglie's claims that particles could behave like waves.

In some ways this makes Science a little like the pile of sand as explained in the book Ubiquity. As grain after grain is added to the pile it becomes more and more unstable. Sometimes there are slight slips; at other times there are near-catastrophic landslides.  Or science is like the punctuated equilibrium model of evolution as described in John Gribbin's brilliant Deep Simplicity. Most of the time evolution just contributes a little variation which make organisms marginally better adapted to their evolutionary niches. But when there is a major ecological catastrophe, evolution goes wild to fill the new ecological niches that have been created.

Kuhn writes with elegance and power. This is a very convincing thesis that had a major impact on the history and the philosophy of Science.

March 2015; 210 pages

"How to teach Quantum Physics to your dog" by Chad Orzel

A research scientist explains the basic principles of quantum physics to Emmy, a dog more concerned with chasing bunnies and evil squirrels.

I did some physics for my degree (which was before some of the stuff in this book was discovered) and I have taught A-level Physics for many years so I understand some of the basic principles. Nevertheless, Orzel gave me a better understanding of the Uncertainty Principle (certainly better than Michael Frayn's who confuses Uncertainty and Chaos Theory in his book The Human Touch) and its necessary consequences: zero-point energy, quantum tunnelling and virtual particles. He also writes very clearly about the difference between the Copenhagen and the Many-Worlds interpretations of the Schroedinger's Cat problem. I'm not sure I was convinced by the Quantum Zeno effect; I'm not sure I understood it properly. I might have to read through this section again. I certainly failed to understand how Bell's Theorem proves that Quantum Theory is a non-local model and how that in turn leads to quantum teleportation; I vaguely understood that quantum teleportation transmits states not particles but I got completely lost as to what this meant.

So I basically got the stuff I understood a bit before and failed to properly grasp the stuff that was new to me. That means that this is not the best explained Physics book I have ever read although, to be fair, it must be the most ambitious. It's like one of those Olympic dives where you have to assess both degree of difficulty and success in carrying out the dive. I guess this means it gets high but not perfect marks.

The dog? The dog helps in the way that ad breaks help in difficult documentaries. The dog gave my brain a chance to make a cup of mental tea and rest a while before coming back to full exertions. Lots of ads are funnier though.

July 2014; 265 pages