Book Extract - The Art of Physics: Eight elegant ideas to make sense of almost everything

It is not as if the lay reader is expected to be familiar with the technical concepts. Bharmal extrapolates only that which is essential to his explanation and proceeds to explain in simple language. Be that as it may, The Art of Physics, may be for you, may be not. You, the reader, decide. Although, all indications are that it is gripping the imagination of many online and they are furiously tagging the author, letting him know that they are enjoying his debut offering.

Zahaan Bharmal read Physics at the University of Oxford. His early career was spent as a policy adviser and speech writer on Whitehall and at the World Bank, where he worked on a range of domestic and international policy issues. In 2005, he won a Fulbright scholarship to Stanford University where he earned an MBA. Since graduating, he has worked for Google, based in London and Silicon Valley and is currently senior director of strategy. Outside work, Zahaan writes about science for The Guardian and has won NASA's Exceptional Public Achievement Medal for services to science communication. He is a trustee of the National Autistic Society. He lives in Yorkshire.

Extracted with permission from The Art of Physics, Zahaan Bharmal, Bonnier UK/ HarperCollins India.

Jaya Bhattacharji Rose

INTRODUCTION

At the World Economic Forum in Davos, the single most valuable commodity is not money, clothes or the car you drive. It's the colour of your badge. Every year, the global elite - political giants, industry titans and a sprinkling of cultural luminaries - descend on this small city nestled in the Swiss Alps to discuss the most pressing issues facing the world. Access to these discussions is strictly controlled and it's the colour of your badge that determines your status for the week. Prime ministers, presidents and CEOs are given coveted white badges, offering unfettered access to virtu- ally everything. Then, in order of descending importance, there are orange, green, purple, blue and red badges. My badge, however, was none of these colours. It was gold. A rich and opulent shade of gold that, for a brief moment, I thought might be a secret class of badge reserved for extra-special attendees. Unfortunately, I soon discovered that gold-coloured badges are close to the bottom rung, the Davos equivalent of the 'participation medals' my children might receive at their school sports day. Sometimes just called hotel badges, gold badges are given only to support staff - individuals who are allowed to enter hotels but literally not set foot beyond the lobby. Any attempts to go further - to enter one of the many splendid hotel conference rooms where the important discussions took place - would be met with prompt refusal by security. Nevertheless, collecting my gold badge on a snowy Sunday morning in January 2020, I was incredibly excited.

The World Economic Forum Annual Meeting is never a dull gathering. But 2020 was a particularly fascinating time to attend such an important event. Although Covid-19 would not force most of the world into lockdown for another few months, the virus had already been identified and the World Health Organization was starting to worry. That and other pressing topics, such as climate change, economic precarity and democratic instability, were some of the key topics of debate. I would not be joining any of these discussions. I was there to support a senior executive - a white-badge holder. This meant my role was diligently organising schedules, writing briefing documents and crafting apt remarks. My job was to get my executive to the meeting room, prepared and on time, and watch the door close in front of me as she walked inside. As much as I would have loved to have entered the room, this arrangement did have one small benefit: as an introvert, it gave me precious time to myself. So while my boss was busy in meetings behind closed doors, I could sit quietly in the hotel lobby on my own, browsing through whatever reading material was lying around. And, at that time, this included the World Economic Forum's 'Global Risks Report'.1 Every year, the Davos organisers publish this weighty report to help provide context and frame the forum's various discussions. The report systematically assesses the likeli- hood and potential impact of the greatest threats facing the world. The 2020 issue described a global economy facing an increased risk of stagnation, and climate change striking harder and more rapidly than expected - all while citizens worldwide protested political and economic conditions and voiced concerns about spiralling inequality. Suffice to say, it was not a fun read. Faced with such epic, intrac- table, existential challenges, none of which have obvious solutions, I felt quite overwhelmed. I would have liked to have been able to contribute and help in some way but, compared to the brilliant minds convening in Davos, I knew I had nothing special to offer. Well, almost nothing. 1 The World Economic Forum 'Global Risks Report 2024'. [The latest edition at time of writing.] https://www.weforum.org/ publications/global-risks-report-2024/.

As I read the impressive biographies of the various white-badge holders attending Davos, I noticed something interesting. As one might expect, the vast majority had advanced qualifications in fields like economics, finance or the political and social sciences. There were experts in medicine, earth sciences and agriculture. There were artists and creators, historians and writers, even philoso- phers and theologians. But I noticed that relatively few had a background in one particular subject. A subject that is arguably the oldest and most fundamental of all academic disciplines. A subject that has helped reveal the very nature of the universe for over two millennia. A subject that I fell in love with as a boy and went on to study at univer- sity. A subject whose lessons and ideas have, in the years since graduating, helped me immeasurably. That subject was physics. What does physics have to do with issues discussed at Davos? Not much, you might think. Davos is about the messy world of people and politics. Physics is about the methodical world of science and reason. Surely the two could not be further apart. Yet in recent years, many people far more influential than me credit thinking like a physicist with their success in fields far removed from physics. The late Charlie Munger, for instance, attributed physics and its fundamental approach to problem-solving for much of his and his billionaire partner Warren Buffett's extraordinary wealth. In his blog, Dominic Cummings, the divisive mastermind behind the Brexit Leave campaign in the UK, credits his political victory to hiring physi- cists, as opposed to people from more traditional fields like politics, business or economics. And unsurprisingly, Elon Musk has spoken on numerous occasions about how physics has influenced his many endeavours, from tackling the challenge of sustainable transport to seeking to protect the future of our species by building rockets to Mars. For Musk, physics, more than any other discipline, is predicated on first-principles reasoning and being able to 'boil things down to their fundamental truths'. And so, sitting in that Davos hotel lobby, I asked myself the questions that ultimately provided the inspiration for this book. Could ideas from physics somehow provide a different way of thinking about global risks? Could physics offer any practical solutions? Ultimately, could physics save the world?

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I haven't always liked physics. In fact, when I was 14 years old and beginning middle school, it's fair to say that I hated it. And it felt like physics hated me too. There were some subjects at school that I found hard and some I found boring. Physics was both. My grades reflected this, and at the end of the first school term my well-meaning but disappointed physics teacher told my parents, with no sense of irony, that my progress 'lacked momentum'. Momentum in physics is defined as mass multiplied by velocity. I quite literally wasn't going anywhere. The truth is, like many young teenagers, I had other things on my mind. I was an anxious, awkward first-generation Indian, growing up in suburban north London. Attending a prestigious but highly competitive private school, I had few friends and found navigating the complexities of social relationships phenomenally difficult. I was more interested in understanding the mysteries of popularity, not physics. The world felt chaotic and miserable. But on my fifteenth birthday, things began to change. As part of their ongoing campaign to encourage me to read more books, my parents bought me Douglas Adams's comic science fiction masterpiece, The Hitchhiker's Guide to the Galaxy.2 I immediately connected with Arthur Dent, the hapless protagonist buffeted by forces beyond his control and outside his comprehension, yet still making something of his life. But more than that, I was drawn to the idea of a single 'answer to the ultimate question of life, the universe and everything'. For me, the idea of such an answer was not only entertaining, it was fantastically comforting.

I realised, of course, that the concept was just a conceit. Adams was making a joke of it, skewering the search for a single final answer by making it ridiculous. Famously, it turns out that the answer to life, the universe and every- thing is the number 42. But as a lonely teenage boy, I became enchanted by the possibility of a single frame- work that could one day help make sense of the world around me. I wanted to find the real version of this frame- work, and physics - the most fundamental of the sciences, probing the very nature of matter - felt like the path to get me there. Like all young students, one of the first physicists I learned about was Sir Isaac Newton. In 1665, the Black Death had killed a quarter of London's population. As this devastating outbreak of the bubonic plague spread, Cambridge University closed its doors and a 22-year-old Newton, then a fellow at Trinity College, was forced into the 17th-century equivalent of lockdown. Returning to his childhood home in Woolsthorpe-by-Colsterworth, Lincolnshire, and free from distractions, he embarked on a period of extraordinary discovery. Legend has it that under the shade of an apple tree, a falling fruit sparked a realisa- tion. Newton hypothesised that the force that pulls an apple to Earth must be the same force governing the motion of the Moon in its orbit. This seemingly simple observation blossomed into Newton's three laws of motion. The first law, or the Law of Inertia, states that an object at rest will stay at rest, and an object in motion will remain in motion with constant velocity unless acted upon by an external force. This law explains why a rocket on the launch pad doesn't go anywhere until its engines fire, and why, once it is on its way to the Moon, it turns its engines off again and coasts on momentum until it needs to slow down at the other end. Inspired by this insight, Newton delved deeper. His second law is commonly expressed as an equation: F = m × a. Force equals mass multiplied by acceleration. Or put another way, mass equals Force divided by accel- eration. This means that the heavier the rocket, the more powerful the engines need to be to get it moving to a velocity that will escape Earth's orbit. Newton also observed that for every force there was an equal and opposite reaction. This principle became his third law, the Law of Action and Reaction. This is the law that makes rockets work in the first place - the thrust of the exhaust in one direction causes the rocket to move the other way. These three laws also paved the way for Newton to develop his universal theory of gravitation, which states that every object in the universe attracts every other object with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them. In other words, the bigger an object's mass, the bigger its gravitational pull (which is why the Earth has stronger gravity than the smaller Moon), and the further away two objects get, the weaker their attraction (which is why the Sun's gravitational pull felt by the Earth is stronger than that felt by more distant planets in the solar system). This elegant expression laid the groundwork for our understanding of the cosmos for centuries to come. It represented a universe that was predictable, ordered and certain. And it also inspired the work of countless other scientists. One of those scientists was Pierre-Simon Laplace. In the 19th century, Laplace made crucial contributions to under- standing planetary motion by applying Newton's theory of gravitation to the entire solar system. But Laplace's real ambition extended well beyond physics. He was driven by a deep desire to predict not just the motion of planets but to formulate an all-encompassing theory of the universe, a theory of absolutely everything. Laplace published a paper that is seen as one of the first sketches of an idea known as determinism. He believed that if someone could know everything about the universe at any moment in time - all the forces at work, the positions of all the objects - with perfect accuracy, then they could, in theory, wind the clock forward and have perfect knowledge of the future.

Postulating what someone might do if they possessed such knowledge, he wrote, 'they would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.

Laplace's influence extended well beyond physics. Born in 1749, he was a contemporary of Napoleon Bonaparte. The two men inhabited distinct realms - war and science - yet Laplace's deterministic philosophy resonated with Napoleon's desire for control and strategic precision. Napo- leon yearned to understand the battlefield like Laplace understood the cosmos, meticulously calculating troop movements, leveraging terrain, and even employing astron- omers for precise artillery targeting. Napoleon envisioned armies as celestial bodies, their movements governed by gravitational pulls of strategy, morale and logistics. He meticulously balanced offensive and defensive forces, seeking advantageous points of leverage like fulcrums, and exploiting enemy weaknesses like gravitational slingshots. This physics-infused world-view extended beyond warfare.

A Philosophical Essay on Probabilities, Pierre-Simon Laplace. Trans- lated from the sixth French edition by Frederick Wilson Truscott and Frederick Lincoln Emory. New York: Dover Publications, 1951. Originally published in 1814.

Laplace's emphasis on laws and order resonated with Napoleon's desire for a stable, centralised France. He sought to impose a rational, scientific structure on French society, mirroring the predictable movements of celestial bodies.

In addition to Napoleon, Laplace's ideas greatly influ- enced other non-scientists throughout the 19th century, shaping many aspects of modern life. The French philos- opher Auguste Comte, for example, came to believe that society could be understood using the same scien- tific methods applied to the natural world - an idea that would later lead to the development of modern sociology. The Belgian statistician and social scientist Adolphe Quetelet applied Laplace's methods to the study of human behaviour, which would ultimately lead to the development of the field of criminology. Laplace's deterministic outlook even found its way into literature, with great writers like Thomas Hardy and Leo Tolstoy exploring themes of determinism and the limits of human control in their novels. Laplace's work was of course not without its critics. The philosopher Henri Bergson argued that Laplace's determinism negated the possibility of human free will. Others, like the novelist Fyodor Dostoevsky, found his mechanistic world-view to be cold and unfeeling. Yet despite these reservations, I was hooked. My once antagonistic relationship with physics began blossoming into a love affair. However impossible, I wanted to live in Laplace's deterministic world. For the first time in my life, I had a reason to work hard. I gained a little momentum. My grades slowly improved and much to my teachers' and parents' surprise, I chose to study physics at A level and was eventually lucky enough to win a place at Oxford to read physics. I soon started to learn things that Laplace didn't know.

There is chaos theory, which says that some deter- ministic systems are so sensitive to the tiniest variations in their initial starting conditions that while the outcome may still follow the patterns laid down by physics, actu- ally predicting them is impossible. And there is quantum physics, based on the uncertainty principle, which says that it's impossible, by definition, to precisely measure both a particle's position and velocity at the same time. The very act of measurement changes the outcome; either its position or its velocity will be affected. But I also learned that for over a century, physicists had been continuing the spirit of Laplace's work through the search for a single unified theory that can take into account the unpredict- ability of chaos theory and the uncertainty of quantum physics, and still explain and link together all aspects of the universe in one all-encompassing model. A simple elegant equation that might fit on a page - the so-called 'theory of everything'.

One of the most intriguing historical characters I came across during my time at Oxford was the little-known German physicist and mathematician Theodor Kaluza. A modest man, Kaluza spoke 17 languages and supposedly taught himself to swim in his thirties just by reading a book. During the summer of 1919, Kaluza sent dozens of letters to Albert Einstein describing what he thought, at the time, might be a potential breakthrough. A few years earlier, Einstein had published his general theory of relativity, a new model for explaining gravity and the behaviour of the universe at epic scales. Einstein's theory was not, however, compatible with the other great pillar of modern physics - quantum theory - which explains the behaviour of the universe at exceedingly small scales. Motivated by a deep desire to unite these theories of the very large and the very small, Kaluza wrote to Einstein with a proposal to add an extra dimension - a fifth dimen- sion - to Einstein's previously four-dimensional model of the universe. Ultimately, Kaluza wasn't able to fully explain both gravity and quantum phenomena in a single theory, but his insight is credited as being a precursor to modern-day superstring theory - our best, at present, hope for developing a theory of everything. More than a century later, finding a single, ultimate theory of the physical universe remains one of the great unsolved prob- lems of science.

As my time at Oxford drew to an end, I began to feel that this goal of unification may forever remain beyond our grasp. And even if physicists did succeed in achieving a theory of everything, it wouldn't be the theory of truly everything, at least not the kind I longed for as a teenage boy. It wouldn't be able to explain all of life's complexities. And so when I finally graduated, I made the tough deci- sion to leave the world of physics behind, embarking on a very different path. I became a management consultant, and then a policy adviser and speech-writer in the British government, and then a strategy director in the technology industry. None of these jobs had anything directly to do with physics. And so as the years passed, my old university textbooks slowly gathered dust in the attic. I soon forgot how to carry out the advanced calculus needed to model the behaviour of subatomic particles, or the differential geometry that underpins general relativity, or any number of other complex topics I had once laboured to master as a student. But I never stopped thinking about physics and found myself continuing to apply the skills I had learned in situations far removed from physics. In fact, whether writing government policies or business strategies, the ability to think like a physicist - breaking things down to their simplest form, coming up with and testing hypotheses, questioning results, and then finding answers to challenging problems - proved invaluable. Physics provided a different way of thinking about and looking at the world. Moreover, ideas from physics were able to help me make sense of many of the same complexities that I struggled with as a teenager. It's these ideas I share in this book.

When I have felt buffeted by forces beyond my control, I have for example thought about chaos theory. Many of us have heard about the butterfly effect - the beating of the wings of a hypothetical butterfly in one hemisphere sparking a hurricane in the next. Physics teaches us that this can happen because even in seemingly deterministic systems, the minutest variation at the start of something can have a dramatic influence on the final outcome, making it almost impossible to predict what will happen. And this principle applies just as well to the catastrophes that hit economies and national destinies. This was a hard lesson I learned early in my career when the dot-com bubble burst, sending financial shock waves around the globe and precipitating a chain of events that ultimately led to me, thousands of miles away and months later, losing my job. In 'The Physics of Getting Fired' we will see how simple changes can quickly lead to deep, intricate complexity. One little tweak, and events spiral out of control. The good news is that physicists have used this knowledge to develop new ways of thinking about how to predict the unpredictable. Catastrophes cannot be prevented - but we can adjust our thinking to prepare for them.

When I felt confused by the idiosyncrasies of human decision-making, I turned to quantum physics. Very few people will admit to making irrational decisions that fly in the face of logic and reason. This leads you to wonder why so many people (including you and me) do this, often without any sense of irony or contradiction. Quantum physics is a whole science based on the seemingly counter-intuitive, with hypothetical cats in a box that are both dead and alive, and objects that manage to be both waves and particles, until you look at them. The key to understanding how two seemingly contradictory things can be true at the same time is the principle of superposition. Superposition can apply both to subatomic particles and ideas in the heads of human beings. In 'The Physics of Irrational Decisions' we apply the principles of quantum physics to human cogni- tion to understand irrationality that makes sense. People don't actually think in neat, straight lines - a realisation that makes the irrational far easier to deal with.

When I've found myself feeling that the world is desper- ately unfair, again, I found myself trying to make sense of this through the eyes of a physicist. In many ways, the universe has always been and will always be unequal. Less than a billionth of a second after the Big Bang, in the vacuum of nothingness, tiny quantum fluctuations in the composition of the universe appeared. Some areas had more energy than others. This inequality allowed pockets of energy and matter to coalesce, eventually leading to the formation of stars and galaxies and planets and ulti- mately us. In 'The Physics of Having Less' we will see that life as we know it would not have come to exist without inequality; in fact, without it there would be no such thing as existence, and now that we do exist, inequality is simply the most efficient way systems find of distributing themselves. When inequality is eradicated, things cease to function. So, instead of worrying about inequality - or, even more futile, trying to stamp it out - it is far more productive to tackle unfairness. Inequality is ever-present in the universe; unfairness does not have to be. Sometimes I don't feel confused or buffeted. I feel I am just steadily, resolutely, step by step moving . . . absolutely nowhere. Everything is lined up, there are no obvious obstacles and I am working hard, putting in the hours every day, all for no obvious result at all. My goals are no nearer. In fact, while momentum is associated with movement and inertia with staying still, they are both part of the same thing. In 'The Physics of Going Nowhere', we see that the laws of thermodynamics tell us energy for change cannot just be willed up. More energy in one place means less in another. The energy required for change is often over- looked, and it comes in two kinds: put simply, the useful and the non-useful kind. Energy can be busily pumped out, but if it is the non-useful kind then it is just wasted.

I've even turned to physics when I've had my heart broken. Before meeting my wife, I had a handful of romantic relationships. Some were good. Others felt one misplaced word away from a blazing row. I struggled to recognise the factors that separated the good relationships from the bad ones. As a physicist, I concluded that it all comes down to stability. Physics teaches us the difference between stable systems, where equilibrium is quickly restored after an upset, and unstable systems, where just the slightest nudge can lead to catastrophe. 'The Physics of Breaking Up' offers words of comfort for the recently or frequently heartbroken. And the same principles that apply to romance can also apply to other kinds of relationships, from friends and family to the relation- ship between governments and volatile voters, leading to outcomes like the UK's break-up from the European Union after Brexit. Physics also gives us the counter- intuitive notion that sometimes the obvious course has the opposite effect desired. Since getting married and moving up to the north of England, I haven't always found it easy to fit in. My own kids make fun of how I pronounce certain words like 'bath' or 'grass'. I can feel like I'm in my own little bubble. Physics tells us how bubbles act. The laws of fluid dynamics mean that their boundaries move at angles to obstacles, they make themselves as short as they can, they merge to form bigger ones, and eventually they settle down into equilibrium. In 'The Physics of Not Fitting In' we will see that the boundaries of language ebb and flow in the same way. The image of bubbles gives us a vocab- ulary for understanding the constant churn of social forces and the behaviour of cultural trends. And while the forces that shape our lives are some- times invisible and unquantifiable, their effect can be felt as strongly as gravity or magnetism. This was a lesson I learned in my early forties, a time when I went through the most clichéd of midlife crises. I felt inadequate and hollow, questioning so many of my choices. In fact, around the time I was grappling with this minor personal crisis, the world faced its own, with the start of the Covid pandemic. In 'The Physics of a Midlife Crisis' we see that our behaviour and attitudes, consciously or unconsciously, are a response to forces around us. Patterns of behaviour, ideas and feelings spread through communities based on what those nearest to us are doing.

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Before I begin, it's worth clarifying a few important points. I am almost certain that Isaac Newton was not thinking about climate change or global poverty - let alone my career or love life - when he developed his theorems hundreds of years ago. His work, and the work of count- less other great physicists since, was about explaining the physical universe, not the human one. So it's natural to ask, is there any real connection between physics and the world beyond physics? Or are the parallels I'm drawing just coincidences?

Putting the specific subject of physics to one side for the moment, I am a great believer in the general power of lateral thinking. This term, first coined by Maltese physician and psychologist Edward de Bono in 1957, is about trying to solve seemingly intractable problems indi- rectly. Sometimes it is necessary to tackle problems from an outside perspective in order to shift thinking. I have seen first-hand the virtues of such lateral thinking. I've learned that it's important to look for ideas in as many different places as possible. And so sometimes, the value of physics lies not in the concrete or quantifiable, but rather in the metaphor or analogy. It is about thinking in a different way.

But why physics, as opposed to any other science? If the adolescent Zahaan had found meaning in another of my school's science offerings - chemistry, say, or biology - would that be the topic of this book instead? What does physics bring to the table that other sciences do not? There is a glib, but misguided, answer to that question. A philos- opher would call it reductionism, which asserts that the secret to understanding any complex system is to break it down into its component parts. If you can understand the parts, the thinking goes, then you can understand the system. A common belief among reductionists is that all science can ultimately be reduced to physics. For example, the foundation of medicine is biology (it's all about making living organisms better), the foundation of biology is chemistry (our bodies are just complex collections of interacting chemicals), and the foundation of chemistry is physics (it's all about the positions of and relations between atoms and molecules). So, all knowledge of medicine can, in theory, be derived from physics. There are others who take an even stronger view, believing that other aspects of our lives - such as economics, psychology and politics - are also essentially just physical processes that can similarly be broken down into smaller and smaller parts that eventually lead back to physics. This is not my view. I am a reductionist, but not as reductionist as that. There are areas where this kind of extreme approach simply does not make sense. Take politics as an example. An extreme reductionist would say this too comes down to physics, because politics is about the behaviour of groups of people; groups are made of individual people, people are made of atoms, and atoms are governed by physics. But does this mean we could predict the outcome of, say, a national election by studying the behaviour of individual atoms inside the brains of every registered voter? Unlikely. In the first instance, we know that we can never have a perfectly accurate picture of every atom in every brain; the laws of quantum physics tell us that there will always be uncertainty. And even if it were theoretically possible, what would be the point? Theorising is not the preserve of physics. Economists already have economics. Psychologists already have psychology. Politicians already have political theory. Physics might contribute insights to these successful disci- plines, but it can't replace them.

For me, physics is about the striving to understand systems in as fundamental and general a way as possible. And in recent years a number of scientists have found a way to use physics to tackle real-world challenges without needing to resort to extreme reductionism. For this book, I may not have interviewed Dominic Cummings or Elon Musk, but I have spoken to a physicist applying the prin- ciples of thermodynamics to combat our insatiable greed for fossil fuels. I have met a physicist who has found a connection between flow systems and the seemingly unstoppable growth in wealth inequality. I have talked to a physicist using the theory of how water evaporates into steam - a process known as phase transitions - to predict and prevent volatile election outcomes. I have met a physicist applying theories of quantum physics to better predict and explain irrational and biased decision- making. And I have even come across someone who has been able to use techniques from statistical physics to predict riots and social violence a decade before they actually happen. All of these people and stories appear in this book.

And so, inspired by Douglas Adams and his own protag- onist's journey through an imperfect universe, let's begin the tour of our mysterious and chaotic galaxy, with physics as our guide.

Zahaan Bharmal The Art of Physics: Eight elegant ideas to make sense of almost everything Ithaka Press, an imprint of Black & White Pubishing Group, Bonnier Books UK, London, 2024. Pb. Pp. 242.