A Universe from Nothing

Why is there something rather than nothing? Lawrence Krauss’s A Universe from Nothing begins with this age-old question—not as theology, but as physics. He challenges the idea that existence demands a creator or a cosmic plan. Instead, he proposes that the universe could have spontaneously emerged from “nothing” purely through the laws of physics. This radical claim draws on cosmology, quantum mechanics, and relativity to argue that nothingness itself is unstable—that “nothing” inevitably gives birth to “something.”

This book is not just about cosmology—it’s also about overturning centuries of philosophical and religious thought. Krauss examines the Big Bang, the nature of space and time, and the unexpected finding that most of the universe’s energy lies in empty space. His argument? Science now provides plausible explanations for our cosmic origin that don’t require divine intervention or metaphysical speculation.

The Science Behind “Nothing”

For Krauss, “nothing” isn’t a philosophical void—it’s a quantum vacuum: a frothing sea of virtual particles that appear and disappear according to quantum laws. This “vacuum” is teeming with potential energy. Modern physics shows that space itself can spontaneously expand and create matter. In other words, empty space is not truly empty; it has energy. This energy’s fluctuations, over billions of years, could lead to the formation of galaxies, stars, and eventually us.

Krauss uses the discoveries of Einstein, Hubble, and Stephen Hawking to demonstrate how the laws of relativity and quantum mechanics allow for universes to appear without prior cause. Gravity plays a surprising role here—it enables negative energy, which can cancel out positive energy to create a universe with a total energy balance of zero. In this framework, the universe is literally a “free lunch,” emerging from nothing and costing no energy to exist.

A Challenge to Theology and Philosophy

Krauss directly confronts centuries of religious inquiry. The belief that creation demands a creator falls apart when physics shows that infinities, quantum instabilities, and spontaneous fluctuations can explain existence. He argues that the theological “God of the Gaps”—invoked whenever science hasn’t explained something—is unnecessary. Physics continues to narrow those gaps, leaving increasingly little room for divine intervention.

Philosophers who define “nothing” as absolute nonbeing criticize Krauss for misusing the term. He retorts that science deals with measurable reality, not word games. “Nothing,” as understood physically, has properties that can be tested and observed. The dynamic nature of empty space—the quantum vacuum—replaces mystical speculation with tangible investigation.

Why This Matters to You

Krauss’s ideas redefine your place in the cosmos. If something can arise from nothing, then meaning isn’t built into the universe—it’s created by you. Knowledge replaces faith as the foundation of wonder. You don’t need divine design to appreciate existence; you can find beauty in being part of nature’s spontaneous creativity. For Krauss, science doesn’t make life bleak—it makes it astonishing. As Richard Dawkins notes in his afterword, the book’s argument does for cosmology what Darwin’s Origin of Species did for biology: it removes the supernatural from our understanding of creation.

Across eleven chapters, Krauss takes you from Einstein’s equations to the fate of the expanding universe, exploring how dark matter, dark energy, inflation, and quantum fluctuations shape reality. The journey culminates in a profound idea: not only could something arise from nothing, but perhaps nothing had to give rise to something. In this sense, existence may be inevitable. And that makes our fleeting moment in the cosmos even more precious.

Krauss begins with the Big Bang—once dismissed as theological, now the cornerstone of science. He recounts how Albert Einstein’s theory of general relativity predicted a dynamic universe even as Einstein himself resisted the idea. Geoffrey Lemaître, a Belgian priest and physicist, was among the first to show that relativity implied an expanding cosmos starting from a tiny, dense point—the ‘Primeval Atom.’ When the Vatican later endorsed this as evidence of Genesis, Lemaître refused the conflation of physics with theology, insisting that science and faith must remain separate.

Einstein, Hubble, and the Expanding Universe

Einstein’s colleague Edwin Hubble confirmed the expansion in 1929 by observing the redshift of distant galaxies. Using Cepheid variable stars (whose brightness follows predictable cycles), Hubble measured distances and demonstrated that galaxies farther away are moving faster. This discovery shattered the old image of a static cosmos and placed humanity in a dynamic, evolving universe billions of years old.

Krauss highlights a poetic consequence: the stars had to die so we could be born. Heavy elements like carbon, iron, and oxygen, essential for life, were forged in stellar explosions. In this sense, theology’s old “Let there be light” gains a scientific echo: the stars died so that matter could become conscious.

Evidence of Cosmic Origins

Through advances in astronomy, physicists confirmed the Big Bang experimentally. The discovery of the cosmic microwave background radiation—the faint afterglow of the early universe—by Arno Penzias and Robert Wilson in 1965 gave irrefutable proof that the cosmos began in a hot, dense state. Later, precision measurements (from projects like WMAP) refined age estimates to 13.72 billion years and showed that space itself is flat within 1% accuracy.

By linking Einstein’s equations, Hubble’s observations, and the composition of matter, Krauss explains that our universe doesn’t require a creator’s hand—it follows inevitable physical processes. This shift, he argues, changed cosmology from metaphysics to measurement. As Lemaître realized, the Big Bang was never an act of divine fiat—it was a natural unfolding of space-time.

When astronomers began weighing galaxies, something didn’t add up. As Vera Rubin discovered in the 1970s, stars at the edges of galaxies moved too fast for visible matter alone to account for their motion. Krauss uses Rubin’s work to introduce one of cosmology’s strangest findings: most of the universe is made of dark matter—invisible, non-luminous particles that outnumber regular matter by more than 10 to 1.

How Weighing the Universe Revealed the Hidden Majority

Using gravitational lensing—a phenomenon first predicted by Einstein—scientists measured how massive clusters bend light from background galaxies. Fritz Zwicky and later Tony Tyson’s team showed that most mass lies between galaxies, invisible yet exerting powerful gravitational effects. This unseen matter isn’t ordinary atoms; it’s something fundamentally different from anything found on Earth.

Krauss explains how particle physics and cosmology intersect here. If dark matter exists, it must consist of new kinds of particles—perhaps remnants of the early universe. Experiments deep underground and at the Large Hadron Collider continue to search for these elusive substances. Discovering them, he argues, would illuminate both the structure of space and the ultimate fate of our cosmos.

Why It Matters

Dark matter shows that what we see is not what is. Less than 1% of the universe’s energy comes from visible matter like stars and planets. The rest is hidden in the dark. Yet this darkness is productive—it shapes galaxies and sustains cosmic structure. For Krauss, it’s poetic: we live in a universe dominated by invisible forces, governed by physics that we’re only beginning to comprehend.

Just when scientists thought they understood cosmic expansion, they found that the universe wasn’t slowing down—it was speeding up. Krauss recounts the revolutionary discovery of dark energy, a form of energy embedded in space itself. In 1998, Saul Perlmutter, Brian Schmidt, and Adam Riess measured distant Type Ia supernovae and realized that galaxies were receding faster than expected. The expansion of the universe was accelerating.

Einstein’s “Biggest Blunder” Reconsidered

Einstein had once added a “cosmological constant” to his equations to balance gravity and keep the universe static—a term he later called his greatest mistake. Krauss and his colleague Michael Turner proposed before the discovery that such a constant might actually exist, representing energy inherent to empty space. They were right: about 70% of the universe’s total energy now appears to reside in this invisible form.

A Universe Dominated by Nothing

Dark energy reshaped cosmology. It means that “nothing”—empty space—isn’t just a backdrop but an active participant, stretching the cosmos faster over time. Krauss describes this as nature’s ultimate trick: the energy of nothingness pushes everything apart, ensuring that the universe will expand forever. This finding confirmed theoretical predictions about inflation and supported the idea that our universe might have arisen from quantum vacuum fluctuations.

In Krauss’s words, the most shocking revelation about existence is that nothing has weight. Empty space brims with energy—dark energy—which not only gave birth to everything but also guarantees its eventual isolation and demise. Our cosmos, he concludes, is a runaway universe, propelled by the energy of absence itself.

How could the universe create itself? Krauss points to inflation—Alan Guth’s groundbreaking theory that explains how a tiny patch of space could expand exponentially in a fraction of a second, flattening the universe and creating all matter and energy. Inflation began as an attempt to solve puzzles like the “flatness problem” and “horizon problem.” It turned out to describe creation itself.

How Inflation Works

Imagine a patch of space filled with energy—the “false vacuum.” According to general relativity, this energy acts as a repulsive gravitational field, forcing space to expand faster than light. When the expansion slows, the energy converts into matter and radiation, producing the particles and galaxies we see today. Krauss calls this the “ultimate free lunch”: the positive energy of matter is perfectly balanced by the negative energy of gravity, giving a universe that costs zero total energy.

Quantum Fluctuations and Cosmic Origins

During inflation, quantum fluctuations—tiny, random variations in energy—became frozen as the universe expanded. Over cosmic time, these minute differences turned into density variations that shaped galaxies, stars, and planets. If inflation occurred, it means the entire universe—everything you see—arose from microscopic randomness in nothingness. As Krauss puts it, “We are all here because of quantum fluctuations in what is essentially nothing.”

This insight bridges cosmology and quantum mechanics: empty space doesn’t just contain potential—it creates. The physics of inflation demonstrates that the rules of nature alone can produce complexity, structure, and life without external direction.

If dark energy keeps driving expansion, Krauss warns, we live in a universe doomed to isolation. In about 2 trillion years, all galaxies beyond our local cluster will recede faster than light, vanishing from view. The evidence of the Big Bang—the cosmic microwave background, the redshift of galaxies, the traces of dark energy—will disappear forever. Future civilizations will see only their own galaxy and will assume, as humanity once did, that the universe is static and eternal.

The Coming Cosmic Forgetfulness

Krauss calls this our “miserable future.” As time stretches, stars will die, matter will decay, and darkness will rule. Even the physical evidence that now proves the Big Bang—the helium abundance, the microwave background—will fade. Cosmology itself will end. Only by sheer chance do we live at a moment when the universe reveals its history. As Krauss and Robert Scherrer joke, “We live at a very special time—the only time when we can observe that we live at a very special time.”

The Meaning of Nothingness

Krauss suggests that what feels tragic is actually poetic. The same physical laws that create us will erase us. Nothingness isn’t merely our origin—it’s our destiny. The universe expands into emptiness, and emptiness expands within us. But far from nihilism, Krauss finds beauty in this cycle. Like Sisyphus smiling as he pushes his boulder, he argues that knowledge itself is consolation: “Our journey provides its own reward.” Understanding that we live in a universe that will vanish gives us reason to cherish the brief spark of existence we possess.

Krauss’s central claim is simple yet staggering: ‘Nothing’ always becomes ‘something.’ In quantum terms, emptiness cannot remain empty. Virtual particles constantly flicker in and out of existence, and under the right conditions, entire universes can materialize. The conservation of energy doesn’t forbid this, because in quantum gravity, total energy can be zero—even for a universe filled with matter and radiation.

Quantum Creation from Nothing

Krauss describes how closed universes can spontaneously form within the quantum vacuum. These mini-universes appear with zero total energy—positive energy from matter perfectly balanced by negative gravitational energy. If inflation occurs, such a microscopic bubble can quickly inflate to cosmic scale, becoming infinite and flat. Stephen Hawking’s work on quantum cosmology and Alex Vilenkin’s “instanton” models show that space itself can arise where none previously existed. The laws of quantum mechanics don’t just permit creation—they demand it.

Implications for Religion and Meaning

This idea, Krauss argues, refutes the need for a “First Cause” or eternal creator. If the universe can arise naturally from instability in nothingness, then creation is not an act of divinity but a physical inevitability. “Nothing,” in this sense, is pregnant with potential. His conclusion is unsettling for theology but exhilarating for science: reality doesn’t owe its existence to intention. It exists because existence is the natural result of the laws of the universe. Or as Krauss puts it bluntly, “Nothing is unstable.”

Having shown how one universe can arise from nothing, Krauss pushes further: perhaps there are countless universes. The multiverse suggests that our own cosmos is just one bubble in an infinite sea of realities, each with different physical laws. This idea, derived from eternal inflation and string theory’s “landscape” of possible dimensions, means that the parameters of physics may not be fundamental—they may be accidental.

A Universe of Many Universes

In Andrei Linde’s model of chaotic inflation, space eternally gives birth to new universes, each separated by vast regions of still-inflating space. String theory adds mathematical support, suggesting as many as 10⁵⁰⁰ possible configurations of reality. Krauss compares this to evolution: we inhabit one of many “cosmic ecosystems.” If universes differ in their constants, only a few will permit life—and we inevitably live in one of those few. This anthropic reasoning, though controversial, resolves why the universe seems “fine-tuned” for our existence.

Beyond Divine Design

In this picture, God is redundant. There’s no need for a supernatural designer when countless universes naturally exist with every possible set of conditions. We are not unique; we are possible. Krauss concludes with humility: the laws of physics may simply be environmental, not eternal. The universe may be “like an onion with millions of layers”—rich, recursive, and self-generating. That realization shifts the role of philosophy and theology: instead of asking why we exist, science asks how. And the answer, Krauss insists, is unfolding in real time through physics itself.