In Pursuit of the Unknown
Ian Stewart

In Pursuit of the Unknown - Book Summary

17 Equations That Changed the World

Duration: 30:44
Release Date: February 17, 2026
Book Author: Ian Stewart
Categories: History, Science
Duration: 30:44
Release Date: February 17, 2026
Book Author: Ian Stewart
Categories: History, Science

In this episode of 20 Minute Books, we delve into "In Pursuit of the Unknown" by Ian Stewart, a mesmerizing exploration of the seventeen most influential equations that have shaped the world of mathematics and physics. Stewart invites us on a journey through the annals of scientific discovery, bringing to life these monumental formulas with engaging anecdotes and palpable enthusiasm.

"In Pursuit of the Unknown" is perfect for anyone captivated by the profound effects of mathematical concepts on society and science. It offers an inviting glimpse into the elegance of these equations for those who may have previously been daunted by complex mathematical symbols. Likewise, it is a treasure trove for those who find beauty in the intricate tapestry woven by mathematical formulas that underpin our understanding of the universe.

The author, Ian Stewart, is a highly esteemed professor emeritus of mathematics at the University of Warwick, England, and a fellow of the Royal Society. Stewart has a deep-seated passion for Lie algebras, dynamical systems, and their connections to chaos theory and biology. His expertise has culminated in several acclaimed popular science books, including "Does God Play Dice? The New Mathematics of Chaos" and "Why Beauty Is Truth: A History of Symmetry."

Join us as we examine the legacy of equations that have not only advanced our grasp of the natural world but also perpetually transform our relationship with the cosmos. Whether you're a mathematics aficionado or simply curious about the hidden power behind these seminal insights, "In Pursuit of the Unknown" promises to enrich your appreciation for the universal language of numbers and its undeniable influence on history and modern life.

Discover the power of equations that shaped our world

If you thought history was just about the grandeur of thrones and the clamor of battlefields, think again. It's less spoken of, but equations—those succinct statements of relationships between variables—are the unsung heroes of human progress. Behind every leap forward, there's an equation jotted on someone's notepad, proof of our fascination and wrestle with numbers to explore the universe.

Equations have set our compass across uncharted waters and even dictated the rhythm of our existence. Consider the elegance of the Pythagorean theorem, a staple of geometry class, which became the cornerstone of navigation. Or ponder over Einstein's groundbreaking equation, E=mc², a compact but monumental discovery that has completely revolutionized our understanding of how time and space intertwine.

You're about to step into a world where numbers assume a life-like quality — a journey where the abstract morphs into the tangible. From the well-known faces of geometry to the mysterious landscape of chaos theory, we'll tap into nine pivotal equations that are as influential as they are insightful.

Along the way, we'll unravel curious facts:

- Unearth the geometrical trinity that binds triangles, circles, and squares.

- Discover why relying too heavily on your car's GPS might leave you planetary positions away from your intended destination.

- Observe how something as mundane as a food processor can flip the switch on chaos.

- Witness how a single mathematical equation could tip the scales and send the stock market into a tailspin.

Prepare to view the world through the lens of mathematics, and appreciate that beneath every well-known milestone, there's a mathematical formula weaving its silent, profound narrative.

Tracing the world with triangles: How Pythagoras's theorem mapped our universe

At first glance, the Pythagorean theorem may seem like a quaint mathematical relic from high school geometry. Yet, this simple axiom that a squared plus b squared equals c squared has done more than propel weary students through exams—it has helped us comprehend the very ground beneath our feet and the vast cosmos above.

This principle posits that in a triangle with one 90-degree angle, the square of the hypotenuse — that's side c — is equal to the sum of the squares of the other two sides, a and b. While delineating a single triangle seems elementary, its implications are immense. This theorem is the linchpin in the art of triangulation, the method by which maps are woven from the tapestry of triangles—each one calculated, carved out from the polygonal landscape to represent lands and continents with stunning accuracy.

Indeed, in the days of old, the world was remapped through the meticulous drafting of these triangles, their sides and angles measured and re-measured to chart the unknown. Modern technology, with its satellite data and computational prowess, may have moved past manual triangulation, but the Pythagorean theorem endures, underpinning the algorithms that discern our position on the planet from signals beamed across space.

But the application of this ancient theorem stretches even further, into the depths of space itself. If Earth is a sphere that can be mapped through this theorem, then what about the universe? To answer such a question might appear to reach beyond grasp, yet, mathematics offers a bridge.

The theorem as taught is confined to the flat surface of a plane. However, when its principles are extended to curved surfaces — such as spheres — we unlock new potential. These advanced interpretations let us use triangles not just to measure the Earth but to take the pulse of space itself, to calculate the curvature of the universe. By examining how triangles behave in the cosmic expanse — how their angles add up — we glean insight into the curvature of all we know. This is the legacy of the Pythagorean theorem: a tool handed down through millennia, instrumental in demystifying the shape of the universe and our place within it.

How Euler's formula shapes our understanding of geometry, from polyhedra to DNA

Imagine a world where the constraints of dimensions are unfettered—where shapes are not defined by their lengths or edges but by their relationships. Welcome to the legacy of Euler's formula: the mathematical key that unlocked this boundaryless realm.

Euler's formula is deceptively straightforward, a quiet revolution, articulated in a relationship that seems like child's play: for any polyhedron, the number of faces (F) minus the number of edges (E) plus the number of vertices (V) always equals two. It is a constant—unchanging, like a beacon denoting the harmony of complex solids. A cube, for example, has 6 faces, 12 edges, and 8 vertices. Crunch the numbers, and there it is—6 minus 12 plus 8 equals 2.

This formula was an inciting spark, inspiring the creation of a new realm of geometry: topology. In this curious new geometry, entities are liberated from the constraints of traditional measure; triangles can morph into circles without so much as a by-your-leave, and squares can fluidly transition into circles. Topology doesn't fuss over forms; it cares only for the core essence of shapes, looking beyond the superficial.

Topology invites a fundamental question: are two shapes fundamentally—if not visually—the same? Can one be transformed into the other without cutting or gluing? Euler's formula is there, steadfast, to answer. By simply counting what's on the surface, we can fathom the deepest topological secrets. If the formula yields the magic number two, they are kindred spirits in topology, even if not in outer appearance.

This profound formula has navigated beyond abstract realms into the very tangible folds of biological tapestries. Consider the helical marvels of DNA, two strands twined in a life-sustaining embrace. It is the handiwork of topology, in conjunction with mathematicians and biologists, that untangles the geometric dance of these molecules—shining a light on how our cells miraculously copy themselves and weave the double helix anew.

Euler's formula, so innocently suggested, so elementary in form, now serves as the compass by which we orient ourselves through both the landscapes of geometry and the intricacies of life's most fundamental molecule.

The bell curve: A mathematical marvel in making sense of the world around us

The ebb and flow of life's various phenomena, from social habits to medical outcomes, often follow a subtle numerical choreography. Enter the normal distribution, a cornerstone of statistical analysis and a faithful lens through which the world's randomness becomes comprehendible.

Positioned squarely within the nineteenth century, mathematicians began to discern a rhythmic pattern in the seemingly chaotic dance of chance events. They saw that most occurrences naturally cling close to the mean, or the average, akin to bees buzzing nearest to the queen. As the values stray from this central point, the likelihood of their occurrence gracefully dwindles, sketching out the iconic bell curve—a symmetrical arch that is the graphical representation of the normal distribution.

The curious mind of Adolphe Quetelet, a Belgian thinker whose expertise spanned both mathematics and sociology, harvested vast arrays of data, from the societal—such as crime rates—to the physical features of individuals, including heights and weights. He noticed that when this data transformed into plotted points on a graph, bell curves emerged, as immaculate as if they were prescribed by mathematical decree.

This discovery defied conventional wisdom. It suggested that, while individual decisions may weave an unpredictable web, the collective behavior of people could surprisingly conform to mathematical laws. The notion was transformative, suggesting a hidden order to human activity on a large scale.

Today, the normal distribution serves as a statistical Swiss army knife. In the field of medicine, it governs the rigors of clinical trials, testing the efficacy of new treatments against the caprices of chance. Consider observational data that cheerfully reports a new drug to be astoundingly more effective than its predecessor.

Yet, the keen eye of statistical scrutiny, aided by the bell curve, knows to question this elation. Data can be misled by innocuous errors—instruments may falter, humans might slip. The normal distribution comes to the rescue, calibrating the belief in this new drug against the null hypothesis—that the purported success is a mere fluke. If the probability that this triumph is just happenstance (a number born out of our bell curve) is meager, then truly, the new medication may be a breakthrough. Thus, the bell curve stands as a sentinel, guarding against the misleading whispers of raw data.

The equation that streams through our lives: The pivotal role of Navier-Stokes

On our blue marble of a planet, where water is as abundant as the mysteries it holds, there was an inevitable call to the curious-minded: to fathom the flows and currents that blanket Earth's surface. And so, the formidable minds of the nineteenth century, playing the role of oracles of hydrodynamics, developed a mathematical key to unlock these secrets—the Navier-Stokes equation.

The influence of the Navier-Stokes equation is nothing short of astronomical. Its grasp extends to myriad scientific quandaries and technological feats. As humanity took to the seas, it was the Navier-Stokes equation that refined the design of ships, allowing them to slice through water with calculated ease. But its reach didn't end at the water's edge.

The sky beckoned next, and airplanes embraced the equation, molding into more efficient forms that glided through the air, all thanks to a deep understanding of flow dynamics. Even our cars, plying the roads in their thousands, owe their sleek, fuel-efficient contours to the Navier-Stokes equation—its calculations so precise that they often replace the arduous and cost-intensive trials within wind tunnels.

But perhaps more intimate is the equation's waltz through our own biology. It charts the rivers within us, guiding the life-giving flow of blood. Surgeons call upon it when re-routing these internal currents during complex operations like coronary bypasses, trusting its insights to navigate the waters of our anatomy.

Then there's the grand tapestry of our climate, a symphony of atmosphere and ocean, each a fluid in its own right. The Navier-Stokes equation serves as the maestro of this symphony, interpreting the patterned chaos, forecasting the future of our climate with each resolved variable. The equation does not merely solve problems; it weaves our understanding of fluid motion into the very fabric of humanity's advancement.

From apples to the stars: Newton's universal law of gravitation

The tale is iconic: Sir Isaac Newton, reclining beneath an apple tree, is struck by a falling fruit and birthed is the universal law of gravitation. Whether the apple's descent is fact or fable, its symbolic impact remains—it represents a moment when human understanding of the cosmos shifted, realizing the forces responsible for a simple fall were kin to those anchoring the moon in orbit.

Newton's law of gravitation, encapsulated in the formula that expresses the gravitational pull between two masses, heralded a wave of enlightenment. With mass and distance as its touchstones, this law professed a profound truth: gravity is not selective, it is universal. Every speck of matter in the cosmos exerts a gravitational influence on its neighbors, near and distant.

This theory, elegant in its simplicity, empowered humankind to cast their eyes skyward and predict celestial ballets with exhilarating precision. It charted the course of planets and moons, transforming the vault of heaven into a grand cosmic clockwork, its gears and cogs meticulously mapped out for eons to come.

In modern times, the same principles guide the arduous planning of space odysseys. At the drafting tables of NASA and ESA, Newton's law lays the groundwork for plotting spacecraft trajectories, be it to the lustrous silver of the moon or the distant red sands of Mars. Visions of Apollo's triumph waft alongside calculations that once ferried astronauts across the vast emptiness.

The gravitational blueprint sketched by Newton has seeded a forest of technological marvels: satellites that whisper to each other across the void, delivering our voices, our images; GPS systems that tell us where we stand on Earth to within a hair's breadth; rovers that tread alien soils, eyes and hands of humanity outstretched to the unknown.

Though Einstein's relativity would eventually refine our perception of gravity, for the everyday motions of planets, probes, and our daily lives, it's Newton's simpler, sturdier framework that still reigns, a testament to the enduring power of an idea birthed in the shade of an apple tree.

Relativity: Einstein's profound legacy on cosmology and daily life

Albert Einstein's theory of relativity is much more than a mere evolution of scientific thought—it is a stroke of genius that forever altered our understanding of the cosmos's very fabric. Like the brushstrokes of a master artist redefining a canvas, relativity has painted our perception of the universe with bold new colors.

In the realm of Sir Isaac Newton, time and space were distinct entities, unyielding and absolute. Objects bore their mass and dimensions as unchangeable badges, immune to the whims of motion. But Einstein turned these notions on their heads. Time mingled with space, a fusion into a four-dimensional continuum where the unchanging character of an object's mass and size was suddenly a romance of velocity and perspective.

Among Einstein's revelations was the arresting truth that speed had a universal yardstick: the unwavering speed of light, immutable and impartial. It cared not for the speed of its source or the observer, a constant against which all movement could be measured.

Even gravity, that age-old force drawing apple to earth, acquired a new identity. No longer a mere force reaching across the void, gravity became the artist, bending and curving space-time itself —a celestial sculptor shaping the grand architecture of the universe.

Our understanding of cosmic spectacles, from the enigmatic allure of black holes to the grand narrative of the universe's birth in a Big Bang, owes much to the insights of relativity. But Einstein's legacy is not confined to the telescopes probing the edges of space-time. It has trickled down into the mundane moments of our everyday lives.

Consider the modern marvel of satellite navigation: systems weaving webs of precise location, reliant on clockwork ticking in the vacuum of space. Relativity whispers into these systems, adjusting their rhythms so the dance between satellites and your car's GPS remains in sync. Neglect these relativistic tweaks — a loss of microseconds here, a gain there — and our navigation would derail, leading us astray by street, town, or if given a year, perhaps even by planet.

Thus, relativity is not a lofty concept tucked away in the hallowed halls of science—it is a principle that pulses through the technology we interact with daily, shaping our world in ways both profound and practical.

Quantum leap: How Schrödinger's wave equation revolutionized our understanding of the micro-world

In the confounding cosmos of the quantum, reality plays by a set of rules that defy our ordinary intuitions. At the atomic and subatomic scale, things get curiouser and curiouser, much like Alice's Wonderland. Here, Schrödinger's equation reigns—a mathematical master key to the riddles of the quantum realm.

In a landscape where light blurs the line between particle and wave, Schrödinger's equation emerged as a beacon of clarity, a radical departure from the classical thought that seemed insufficient to grasp this microcosmic oddity. The slope of the nineteenth century found physicists juggling with light's dual nature, confronting its wave-like behavior in some settings, its particle-like antics in others.

Schrödinger’s contention was audacious, that every speck of matter thrives on ambiguity, living a double-life as both particle and wave. His mathematical model embraced this duality, presenting matter as a wave-function. It was the foundation upon which quantum theory was constructed—a theory where probability reigns and electrons can exist in a ghostly realm of 'might be's and 'could be's.

Yet, this isn't esoteric knowledge locked away in the ivory towers of academia; it's the heartbeat of the technology cradling our modern society. Take the ubiquitous semiconductor, the building block of memory chips—a material whose demeanor sways on the baton of electrical conductivity. Understanding electrons' celestial dance through the crystalline lattice of these semiconductors demands a quantum view.

Without the insights of Schrödinger's equation, the electronic symphonies played out in our computers, phones, entertainment systems, and the microprocessors governing our cars and appliances would be silent. They all sing with a quantum voice, a chorus made possible by the wave mechanics that Schrödinger inscribed into the annals of science.

In partnership with Einstein's relativity, quantum theory forms the backbone of our contemporary grasp of the universe. It's a testament to our deepening conversation with nature, bridging the once impenetrable divide between the observable and the operatic stage of the very small. The echoes of Schrödinger's equation thus vibrate through every aspect of our digitally orchestrated lives.

The butterfly effect: How chaos theory influences science and daily decisions

From an inconspicuous seedling in the gardens of mathematics, chaos theory has flourished, spreading its branches across the canopy of scientific understanding. It's an enigmatic theory that unveils a paradoxical truth: within the heart of determinism lurk unpredictable outcomes—a doctrine of chaos without chance.

Consider the domestic whirlwind of a food processor. Its blades, obedient to the simple command of revolution, cut through their culinary charges. Yet the motion of the ingredients tossed within is anything but orderly. No slice or shred proceeds with predictability; chaos is the master chef here.

Chaos is not confined to kitchen appliances; it has serious implications in the natural sciences too. Biology offers a neat illustration with models that predict the growth of populations based on preceding generations. What seems like a straightforward matter of calculable lineage turns to wild unpredictability with the slightest nudge of uncertainty. A single misstep in initial data and the future swells into a forest of possibilities, each as likely as the last — the signature of chaos laid bare.

Chaos theory, however, is far more than an academic novelty; it permeates our everyday experiences, reshaping scientific thought and practical approaches alike. Take weather forecasting—an arena where chaos plays mischief with meteorological destinies. The atmosphere, deterministic in its essence, is a playground for chaos, with countless variables intertwining in a complicated dance. Instead of searching for precision in a single forecast, meteorologists have learned to embrace the chaos. They run an ensemble of simulations, a chorus of potential weathers, to gauge the likelihood of tomorrow's skies.

Beyond the skies, chaos has even found use in the artful science of mixing—whether blending pharmaceutical concoctions into uniform pills or integrating ingredients into culinary delights.

Chaos theory compels us to reconsider the illusion of control we presume over our deterministic systems. It reminds us that beneath the veneer of order, unpredictability lurks, ready to emerge from the flap of a butterfly's wings — a lesson not just for the academic mind but for all those who seek to navigate the swirling complexities of life.

Unlocking finance with Black-Scholes: A double-edged sword of economic growth and crisis

In the towering world of finance, derivatives stand as monuments to human ingenuity and complexity. These instruments, far removed from the tangibility of currency, are essentially bets upon bets—a labyrinthine layer of speculation that underpins much of the banking system's might. It was the Black-Scholes equation that provided the key to harnessing the wild potential of these financial derivatives, spurring unprecedented growth in the sector.

Consider the options market, where contracts are crafted allowing the acquisition or sale of assets in the future at a predetermined price. Picture a merchant locking in a deal to buy rice at a fixed cost, months down the line. Should they wish to exit this agreement prematurely, the question of the contract's current value looms large. To trade blindly is a gamble fraught with peril, where a misjudged price could spell financial ruin.

Enter the Black-Scholes equation, a mathematical soothsayer that calculates an option's worth at any point before its culmination, assuming the market doesn’t stray from its typical behavior. This formula became the foundation upon which anyone could stride into the financial arena with a semblance of certainty.

However, the heady ascent invited by Black-Scholes carries an intrinsic risk. The financial domain, insatiable for innovation, crafted increasingly intricate derivatives—ghostly assets born of other speculative contracts, a house of cards with its stability resting on mathematical precision.

Yet reality offers a sobering counterpoint: a vast majority of futures traders see their investments dissipate. The narrative that math could infallibly plot the trajectory of markets began to crumble. The cozy assumptions that propped up the Black-Scholes equation proved flimsy against the tempestuous nature of global finance. In this gulf between theory and practice, between the elegance of equations and the chaos of reality, lay the seeds of disaster.

The financial crisis of 2008-09 is a stark reminder of the perils embedded in formula-driven trading, a cautionary tale of what happens when faith in mathematical precision collides with the indomitable spirit of the market. It underscores the delicate balance between leveraging mathematical models for growth and the vigilance needed to avoid cascading into economic abysses.

The numbers that shape our universe: The profound impact of equations

The insights gleamed from "In Pursuit of the Unknown" reveal a stunning truth: mathematics is not just a language of the mind, but the undying force that sculpts our reality. Equations are the threads from which the tapestry of human progress is woven. They are silent architects, shaping every facet of modern existence.

From the precision of Pythagorean geometry that laid the framework for mapmaking, to the revolutionary Navier-Stokes equations that dictate the flows of liquids and gases, equations pervade our understanding and manipulation of the physical world. Einstein's theory of relativity has expanded our comprehension of time and space, knitting the cosmos into an interconnected whole, while Schrödinger’s equation delves into the quantum mysteries that form the substrate of technology that fills our homes and workplaces.

Chaos theory has unveiled the unpredictability laced within deterministic systems, altering our perspective on the natural world and the phenomena ringing through our daily lives. The Black-Scholes equation, with its valiant attempt to decipher the net of finance, stands as a powerful reminder that while mathematics can illuminate paths, it is no shield against the inherent volatility of human enterprises.

Thus, the core message of this narrative is clear: equations are more than mere abstractions or academic pursuits. They are potent tools—a magic of sorts—that have enabled humanity's most astonishing feats, from plotting courses to distant celestial bodies to streaming visuals and sounds across the globe. They have turned once-dreamt impossibilities into tangible experiences, transforming not just how we interact with the world, but ultimately, how we experience the very essence of existence.

In Pursuit of the Unknown Quotes by Ian Stewart

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