A Book That Inspired Generations: Review of Stephen Hawking’s “A Brief History of Time”

On 1 April 1988 — April Fools’ Day, a detail Stephen Hawking rather enjoyed — a slim, 198-page book appeared in bookshops with an unlikely ambition: to explain the origin, structure, and possible end of the universe to readers with no background in physics at all. Hawking’s publisher warned him that every equation he included would halve his readership. He included exactly one: E = mc².

A Brief History of Time: From the Big Bang to Black Holes went on to sell more than 25 million copies in over 40 languages, spend a record-breaking 237 weeks on the Sunday Times bestseller list, and turn a physicist confined to a wheelchair, speaking through a voice synthesiser, into one of the most recognisable scientists on Earth. It remains one of the best-selling and least-finished books in publishing history — famously “the most unread bestseller of all time,” in the words repeated by critics for decades. That reputation is not entirely fair to the book, and this is the story of what it actually contains, why it mattered, and why it still does.

The Physicist Behind the Book

Stephen Hawking was diagnosed with a slow-progressing form of motor neurone disease in 1963, at the age of twenty-one, shortly after beginning his graduate work at Cambridge. He was told he had roughly two years to live. He lived for 55 more, becoming the Lucasian Professor of Mathematics at Cambridge — the chair once held by Isaac Newton — a position he held for thirty years.

His scientific reputation was built well before the book existed. With Roger Penrose, he proved that Einstein’s general relativity implies the universe must have begun from a singularity — a result now known as the Penrose-Hawking singularity theorems. In 1974, he predicted that black holes are not perfectly black at all: they slowly emit radiation and, over immense timescales, evaporate. This process, now called Hawking radiation, was controversial at first and is today regarded as one of the most important results in theoretical physics — a genuine bridge between quantum mechanics and gravity, the two theories the book itself is built around.

By the mid-1980s, having lost his voice after a tracheotomy, Hawking communicated through a speech-generating device controlled first by a handheld switch and later by a single cheek muscle. It was in this state — internationally respected among physicists, almost unknown to the public, and increasingly unable to speak — that he decided to write a book for everyone else.

From the Big Bang to Black Holes

The book opens, famously, with an anecdote about a public lecture on astronomy, at the end of which an elderly woman in the audience declares that the universe is really a flat plate resting on the back of a giant tortoise. Asked what the tortoise stands on, she replies that it is turtles all the way down. Hawking uses the story to introduce the central question of the book: what is our universe actually resting on, and how do we know?

From there, the book moves chronologically through the history of cosmological thought — Aristotle’s geocentric universe, Ptolemy’s epicycles, Copernicus’s heliocentrism, Galileo’s telescope, Kepler’s ellipses, and Newton’s laws of motion and gravity — before arriving at the two pillars of twentieth-century physics: Einstein’s general relativity, which describes gravity as the curvature of space-time caused by mass, and quantum mechanics, which governs the strange probabilistic behaviour of particles at the smallest scales.

The heart of the book is the collision between these two frameworks. General relativity predicts singularities — points, such as the birth of the universe and the centre of a black hole, where its own equations break down. Quantum mechanics predicts that nothing can ever be perfectly still or perfectly empty, thanks to the uncertainty principle. Hawking’s own career was built on the places where these two theories are forced to confront each other, and much of the book is an attempt to explain, without mathematics, what that confrontation reveals: black holes that are not entirely black, singularities that quantum effects might soften, and a universe whose beginning may not require a beginning at all.

The No-Boundary Proposal and Imaginary Time

Among the book’s most ambitious ideas is the no-boundary proposal, developed by Hawking with the physicist James Hartle in 1983. Standard cosmology describes the universe expanding from a singularity — a moment where time itself begins, and where the question “what happened before the Big Bang?” becomes meaningless, since there was no “before.”

Hartle and Hawking proposed something stranger: that if you treat time, mathematically, using what physicists call imaginary time — a formal device where time behaves more like an additional dimension of space — the sharp edge of the Big Bang singularity smooths away entirely. In this picture, asking what came before the beginning of the universe becomes akin to asking what lies north of the North Pole

The question does not have an answer because it is not a well-formed question; the universe, in this model, simply has no boundary in time, past or future. It remains one of the most genuinely difficult ideas in the book, and one of the most quietly radical proposals in modern cosmology — an attempt to make the universe’s beginning a consequence of physical law rather than an unexplained starting assumption.

Wormholes, Time Travel, and the Arrows of Time

Later editions of the book added a chapter on wormholes and time travel, prompted by the explosion of public interest following the book’s initial success. Wormholes are hypothetical tunnels through space-time, permitted in principle by general relativity, that could in theory connect two distant points in the universe — or two distant points in time.

Hawking is careful to explain why they remain firmly theoretical: keeping a wormhole open would require a form of matter with negative energy density, something no confirmed physics currently provides, and any attempt at time travel raises paradoxes, such as the classic scenario of a traveller preventing their own birth, that most physicists take as evidence against the possibility rather than a puzzle to be solved.

The book also introduces what have become known as the arrows of time — the several distinct senses in which time seems to move in only one direction. The thermodynamic arrow is the steady increase of disorder, or entropy, described by the second law of thermodynamics. The psychological arrow is the direction in which we remember the past but not the future. The cosmological arrow is the direction in which the universe is expanding rather than contracting.

Hawking spends real effort probing whether these three arrows must always point the same way, and concludes that our own existence as observers may only be possible in the stretch of cosmic history where they do — an early, elegant example of what physicists call anthropic reasoning.

The Search for a Theory of Everything

The book’s final movement concerns the long, unfinished search for a single theory that would unify gravity with the other fundamental forces — electromagnetism and the strong and weak nuclear forces. Einstein spent the last three decades of his life chasing such a unified field theory and never found it. Hawking devotes real attention to string theory, the leading candidate in his own era, which proposes that the fundamental constituents of reality are not point particles but tiny, vibrating one-dimensional strings, with different vibrational patterns corresponding to different particles.

Hawking closes with the hope that had, by his own account, animated the entire project: that a complete theory would eventually be simple enough, and its implications important enough, for it to be broadly understood — so that everyone, not only scientists, could take part in the discussion of why the universe exists at all, rather than not existing. Whether such a theory has been found remains an open question in physics to this day; string theory itself remains unconfirmed, and the search for a unified account of gravity and quantum mechanics is still one of the central unsolved problems in the field.

Why the Book Became a Phenomenon

The commercial success of A Brief History of Time surprised almost everyone involved, including its author. Several explanations are usually offered. The near-total absence of mathematics — a deliberate choice, forced by his publisher’s warning that each equation would cost half the readership — made the book approachable in a way few serious physics texts had ever been. Hawking’s own gift for analogy and quiet humour carried readers through genuinely difficult concepts without condescension. And the story of the author himself, visibly and severely disabled yet producing work of this ambition, gave the book a human dimension that pure science writing rarely has.

The astrophysicist Carl Sagan, who wrote the introduction to the first edition, recalled attending a Royal Society ceremony in London in 1974 and watching a young man in a wheelchair slowly sign his name in a book whose earliest pages carried the signature of Isaac Newton. Sagan called Hawking a worthy successor to Newton and to Paul Dirac, both former holders of the same Cambridge chair — a lineage explored further in our article on Paul Dirac, the physicist who predicted antimatter. Even then, Sagan wrote, Hawking was already a legend.

Later Editions and Adaptations

The book’s success generated a small publishing industry of its own. An illustrated edition followed in 1996, adding photographs, diagrams, and computer-generated images to make the concepts even more accessible. A tenth-anniversary edition updated the science to reflect new discoveries. In 2005, Hawking co-wrote A Briefer History of Time with the physicist Leonard Mlodinow, a shorter and further simplified version aimed at readers who had found even the original too demanding.

The film director Errol Morris adapted the book into a 1991 documentary, produced by Steven Spielberg, which combined material from the book with interviews of Hawking, his colleagues, and his family — a biographical portrait rather than a straightforward filmed lecture. A companion six-part television series, Stephen Hawking’s Universe, followed in 1997. The book’s cultural reach extended further still: Hawking made cameo appearances as himself in Star Trek: The Next Generation and The Simpsons, cementing his status as one of the few working theoretical physicists to become a genuine popular icon in his own lifetime.

The Question of God

One thread of the book generated more debate than any other: Hawking’s repeated, careful engagement with the idea of God. He does not resolve the question, and readers on both sides of it have long claimed the book as support for their view. What Hawking does is note that if physics could ever produce a truly complete theory — one requiring no external cause or starting assumption — then there would be, in his words, nothing left for a creator to do.

Whether the universe needs a first cause at all, or whether a no-boundary model of the kind he and Hartle proposed removes the need for one, is a question he leaves open rather than answered, and it is precisely that openness, together with his evident respect for the scale of the question, that many readers found unexpectedly moving in a book of physics.

The “Unread Bestseller” Reputation

The book’s reputation as the most bought and least finished bestseller of all time has become something of a running joke in publishing circles, and it is not entirely without basis. Surveys of reading habits have repeatedly found that popular science books with genuine mathematical or conceptual difficulty are disproportionately abandoned partway through — the so-called “Hawking Index,” a tongue-in-cheek measure popularised by data scientists analysing Kindle highlighting patterns, estimated that the average reader made it only a modest fraction of the way through before highlighting activity dropped off.

Hawking himself was reportedly aware of the reputation and untroubled by it, taking the view, according to those who knew him, that a book bought and partly read, sitting prominently on a shelf, still did more to spread curiosity about the universe than a book never bought at all. Whatever the precise completion rate, the book undeniably succeeded at its stated goal: bringing genuinely difficult physics into millions of homes that would otherwise never have encountered it.

Hawking’s Later Life and Legacy

Hawking continued working for three decades after the book’s publication, producing further popular titles including The Universe in a Nutshell and, with Mlodinow, The Grand Design. He died on 14 March 2018, at the age of 76 — a date that happened to fall on the anniversary of Einstein’s birth, and only months before what would have been his own 76th birthday, itself the anniversary of Galileo’s death.

His ashes were interred at Westminster Abbey, between the graves of Isaac Newton and Charles Darwin, in recognition of a body of work that had, in the span of a single working life, reshaped how physicists think about black holes, the birth of the universe, and the deep partnership between gravity and quantum theory.

His death prompted tributes from across science and public life, but perhaps the most fitting was quieter: within hours, radio telescopes around the world beamed a musical setting of his words, composed for the occasion, toward the nearest black hole, 3,500 light-years away — a final message sent, fittingly, into precisely the kind of object that had defined his scientific life. For the story of another towering figure who shaped that partnership from first principles, see our article on Srinivasa Ramanujan.

Why It Still Matters

Some of the science in A Brief History of Time has moved on. String theory has not delivered the unified account Hawking hoped for; observational cosmology since 1988 — including the discovery of the universe’s accelerating expansion and the detection of gravitational waves — has added chapters the original book could not have written. But the core of the book has aged remarkably well: the explanations of black holes, the Big Bang, and the tension between relativity and quantum mechanics remain sound introductions to questions physicists are still working on.

Its real legacy, though, may be less about the specific physics than about what it proved was possible: that a book almost entirely free of mathematics could carry millions of ordinary readers into genuinely difficult ideas about space, time, and the origin of everything, and leave many of them changed by the experience. That is a rarer achievement than the science itself, and it is the reason the book is still worth reading nearly four decades after an April Fools’ Day publication date that turned out to be no joke at all.

Frequently Asked Questions

Sources

• Wikipedia — A Brief History of Time
• Wikipedia — Stephen Hawking
• The Official Stephen Hawking Website — A Brief History of Time
• Encyclopaedia Britannica — Stephen Hawking
• Nobel Prize Foundation — Background on Penrose-Hawking Singularity Theorems