Einstein’s Fridge: The Science of Fire, Ice and the Universe 
by Paul Sen.
William Collins, 305 pp., £20, April, 978 0 00 826279 2
Show More
Show More

Thethreat of catastrophe is alluring. In 1990, when the existence of global warming was routinely contested, a Nasa scientist spoke frankly on television: ‘It’s easier to get funding if you can show evidence of impending human disasters … Science benefits from scary scenarios.’ Last year, the Doomsday Clock was set to a hundred seconds before midnight, indicating that man-made global apocalypse is closer than at any point since the clock was created in 1947. This year, it has been kept at that setting as a ‘Covid wake-up call’, but the chief apocalyptic risks are still nuclear destruction and climate change.

In Einstein’s Fridge, Paul Sen exhorts us to study thermodynamics so that we might make better-informed decisions about how to save the world. The study of thermodynamics began in the 17th century with attempts to create a vacuum inside a glass globe – the subject of Joseph Wright’s famous picture An Experiment on a Bird in the Air Pump (1768) – but it wasn’t established as a science until the Victorian era, when Scottish physicists drew on French research to improve the efficiency of the massive steam engines driving industrialisation. The word itself combines the Greek terms for heat and force, but its application now extends way beyond machinery to include biological processes, quantum mechanics and information processing.

All fridges, including Einstein’s, are governed by the laws of thermodynamics, which rest on the distinction between heat and temperature. As Sen puts it, ‘Heat never spontaneously flows from cold to hot.’ If I hold a hot stone in my cold hands, it will cool down. Similarly, food placed inside a refrigerator will get colder as its heat passes into the concealed coolant. The coolant will get warmer, but it will still be at a lower temperature than the kitchen outside, so it cannot spontaneously transfer that extra heat into the room: some work (typically electrical) must be performed to pump it out and keep the coolant sufficiently cold to do its job.

As statistical methods were taken up by physicists during the 19th century, probability theory was used to analyse the relationship between the fluctuations of countless tiny molecules and the large-scale observable behaviour of a system. This work culminated in the modern formulation of thermodynamics, which relies on the concept of entropy, a term coined in the 1860s. Real machines are different from the ideal versions in mathematical models. Inside a factory, the grating of pistons and the clanging of metal causes the continual dissipation of tiny amounts of energy. This process is irreversible, and the lost energy can’t be retrieved to carry out useful work. Every time you ride a bicycle or freeze a bag of peas or carry out a search on Google, some energy becomes unavailable, and the total amount of entropy in the universe gets ever so slightly larger. Because entropy is constantly increasing, it marks a direction in time: eventually, no energy will be available for use and the universe will grind to a halt. In The Time Machine (1895), H.G. Wells evoked this grim prospect. As his travellers approach the far distant future, ‘the darkness grew apace … All the sounds of man … the stir that makes the background of our lives – all that was over.’

In the 1940s, Claude Shannon – an American scientist employed by AT&T to carry out blue-sky research – unexpectedly tied entropy to information. Some messages have a higher content value than others: it’s much more interesting to be given the number of the lottery ticket that will win tomorrow than any of the numbers destined to lose. Shannon devised a way to quantify the amount of information carried in a message, and noticed that the mathematical laws governing its transmission closely resembled those of thermodynamics. In the static endpoint universe Wells envisaged, machines could not function and, just as important, information could not flow. It has since become clear that the basic principles of thermodynamics govern any situation in which energy and information are involved, including biological reproduction, sub-atomic processes and the behaviour of black holes.

Stephen Hawking was told when he was writing A Brief History of Time that each equation he included would halve sales. In the event he kept just one – E = mc2, Einstein’s fundamental formula of mass-energy equivalence – but Sen has eliminated them entirely. Einstein’s Fridge is a superb introduction to the complexities of the universe, but Sen claims a bigger role for the book than that, asserting that learning from the past will help us to protect the future. In principle it seems right that better-informed citizens would be in a stronger position to challenge the decisions made by those in power. But what sort of knowledge do they need? Understanding the molecular intricacies of vaccine protection would do little to help anyone wishing to expose the weaknesses in the government’s financial and political strategies for minimising the effects of the pandemic. Yet, according to Sen, learning about the developments and setbacks in thermodynamics over the last couple of centuries will somehow help to safeguard the future of humanity.

As Sen occasionally seems to recognise, his narrative entwines two conflicting plotlines. In the prologue, he promises that his account of thermodynamics will explore the reciprocal interactions of science and society. Over the last few decades, historians of science have adduced countless examples demonstrating that science is embedded in a wider culture, its applications and achievements inseparable from political, commercial and imperial interests. Yet in the rest of his book Sen mostly avoids such issues, preferring instead to explain theories and celebrate individuals. By the end, he seems to have moved to a binary vision of society: scientists (the good guys) and everybody else. For him, scientific research needs no external justification.

Sen’s scientists inhabit an idealised zone where the baton of truth passes from one individual to the next. This risks giving in to the way these people liked to present themselves and their work. For instance, Sen describes the classic paddle-wheel experiment James Joule carried out in a brewery. But he doesn’t mention what the historian Otto Sibum found when he attempted to replicate it: Joule had omitted several essential details from his instructions, notably the presence of co-experimenters – the countless ‘invisible assistants’ (many of them women) who have been obliterated from so many historical records.

The main characters in Sen’s story are almost all men, though he pays generous tribute to Emmy Noether, a German mathematician who carried out fundamental work on theories of symmetry and the laws of energy conservation. At the New York World’s Fair in 1964, hers was the only female face in a mural depicting eighty Men of Modern Mathematics. Women feature here mainly in cameo roles to spice up the narrative, including a sex scene among the thermionic valves in the MIT computer room, and lengthy speculations about the relationship between James Clerk Maxwell and his wife, Katherine, with whom he occasionally collaborated.

Seninsists that to make decisions about electric cars, wind farms and nuclear energy requires a grasp of the scientific fundamentals. But why should a familiarity with Carnot cycles, Maxwell’s demon or Turing’s Universal Machine help a reader looking for ways to slow down the pace of climate change? Understanding the mechanism of a phenomenon is very different from being able to mitigate its impact. The physicist John Tyndall identified the greenhouse effect in 1860, but generations of scientists have failed to instigate reforms that might slow it down. Perhaps it would be better to focus not on explaining the science, but on exposing the political and industrial interests that dictate the course of scientific research.

‘Knowledge is shaped by and, in turn, shapes society,’ Sen writes in his prologue, and he might have presented thermodynamics as an excellent example of that relationship. Instead, Einstein’s Fridge reinforces the argument that technological progress is driven by a disinterested thirst for knowledge, even though the mathematical laws of thermodynamics were developed more than a hundred years after steam engines were first introduced to pump water out of Cornish silver mines. Sen blames Watt and his business partner, the factory-owner Matthew Boulton, for causing a thirty-year hiatus by manipulating the patent system to ward off competitors, but engines produced power and generated money long before scientific laws and equations were developed to explain how they worked. When Boulton invited James Boswell to admire Watt’s steam-operated engines, he boasted: ‘I sell here, Sir, what all the world desires to have – Power.’

The fridge in Sen’s title illustrates some of the inconsistencies in his approach. Einstein is portrayed here as a benevolent practical genius who, after hearing about a fatal accident in a Berlin kitchen, decided to do his bit for humanity by inventing safer, cheaper devices. He teamed up with the Hungarian physicist Leo Szilard, but after they managed to design a successful model, the goalposts shifted. Sen’s brainy humanitarian mutated into a keen businessman who took out 45 patents in six different countries and negotiated generous royalties from the German Electric Company. The venture fizzled out in the face of commercial competition from the cheap coolant Freon, a major contributor to holes in the ozone layer.

Despite ample evidence of this sort, the myth of the pure scientific ‘quest to discover the truth about the universe’ persists. To take just one example, Marie Skłodowska Curie’s reputation as a scientific martyr is often supported by quoting her denial (carefully crafted by her American publicist, Marie Meloney) that she derived any personal gain from her research: ‘There were no patents. We were working in the interests of science. Radium was not to enrich anyone. Radium … belongs to all people.’ As Eva Hemmungs Wirtén pointed out in Making Marie Curie, this claim takes on a different hue once you learn that, under French law, Curie was banned from taking out a patent in her own name, so that any profits from her research would automatically have gone to her husband, Pierre.

Science enthusiasts often stake out the intellectual high ground. Sen claims that science already holds all the solutions to climate change (perhaps unsurprisingly, he doesn’t dwell on the ways in which technological innovation dramatically accelerated its onset). In addition to expanding our use of renewable energy sources, he argues, we should increase our investment in nuclear power (‘carbon neutral and considerably safer than most people think’), as well as geothermal and tidal power. He gives the credit for all the benefits of such innovations to supposedly disinterested scientists, while laying the blame for any side-effects on blinkered, ambitious politicians. Many physicists had recourse to a similar argument in 1945 after the US dropped two atomic bombs over Japan (others fled to the life sciences or abandoned research). It was during this time of panicked reflection that the Doomsday Clock was set up by the Bulletin of the Atomic Scientists as a perpetual reminder that the fate of the world is a collective responsibility, and that scientists are not exempt.

In exonerating scientists from blame for the uses their findings are put to, Sen treats them as an elite group set apart from the rest of humanity. In Britain, this sort of thinking originated in a class-driven ideological contrast between natural philosophers, who were (supposedly) above such mundane concerns as financial reward, and inventors, who were disparaged for working with their hands and seeking commercial gain. Wordsworth idealised Isaac Newton as a ‘Mind forever/Voyaging thro’ strange seas of Thought, alone’, but James Watt received less reverent treatment. Although steam engines generated much of the nation’s wealth and international power, when a statue of Watt was planned for Westminster Abbey after his death in 1819, some protested that it wasn’t an appropriate place to celebrate a mechanical engineer who had sued his business competitors. After a long and acrimonious debate, the statue went up with a compromise inscription honouring Watt as ‘an original genius, early exercised in philosophic research’.

‘Iwent into science a great deal myself at one time,’ Dorothea Brooke’s uncle remarks in Middlemarch, ‘but I saw it would not do. It leads to everything; you can let nothing alone.’ Sen seems to think scientific progress is independent of political or commercial influence or the rise of global capitalism. I believe, by contrast, that the consolidation of the image of science as humanity’s most worthwhile endeavour is the result of what amounts to a sustained promotional campaign. Science is not a well-defined field of human activity that advances steadily; it is an unstable, shifting set of practices that influence and are influenced by other social processes. Its claim to superiority hinges on the way it is valued, not on any intrinsic quality, and its rise to prominence has been far from inevitable. As late as the 19th century, London’s Royal Society remained an unsubsidised poor relation; it flourished only after it aligned itself with projects to augment British industry, global trade and imperial power.

Sen doesn’t mention C.P. Snow, but he does echo the warnings Snow made in his ‘two cultures’ lecture, delivered in 1959 during the Sputnik era, when the Doomsday Clock was set at two minutes to midnight. British intellectual culture was, he argued, dominated by the humanities, but the world’s problems – how to reduce poverty, how to distribute wealth, how to ensure a future for humanity – could never be solved by a society whose ‘natural Luddites’ (‘literary intellectuals’) had no more knowledge of modern physics than their ‘neolithic ancestors’. Sen, like Snow, believes that the answers are to be found in science education, although that again seems to contradict his assertion that resolving our current predicament depends on political change.

In Sen’s progressivist model, pouring money into science must bring future improvement. But there is no contradiction in acknowledging, on the one hand, the benefits of modern medicine and centrally heated homes, and insisting, on the other, that there are choices to be made about our possible futures. Should medical researchers be concentrating on the use of sophisticated genetic engineering to treat rare conditions, or on basic health measures for the millions of people around the globe who suffer from curable afflictions? This is an old question, but it remains as vital as ever.

Send Letters To:

The Editor
London Review of Books,
28 Little Russell Street
London, WC1A 2HN


Please include name, address, and a telephone number.

Read anywhere with the London Review of Books app, available now from the App Store for Apple devices, Google Play for Android devices and Amazon for your Kindle Fire.

Sign up to our newsletter

For highlights from the latest issue, our archive and the blog, as well as news, events and exclusive promotions.

Newsletter Preferences