by Martin Rees — Newbooks Library

Prologue

Could God Have Made the World Any Differently?

Rees introduces the central mystery: why anything exists at all, and why our universe’s specific recipe permitted complexity and life. He argues that a biophilic universe requires exquisitely fine-tuned laws—many alternative recipes yield stillborn universes with no atoms, no chemistry, and no planets. If fundamental theory permits multiple recipes, then our universe may be just one element in a vast multiverse, and what we call laws of nature are merely local bylaws. Rees contends the multiverse concept belongs to empirical science, not mere metaphysics, and that our cosmic habitat may be a fertile oasis within this grander ensemble.

Part I — From Big Bang to Biospheres

Chapter 1: Planets and Stars

Rees traces how our understanding of the Sun evolved from Lord Kelvin’s erroneous age estimates to the discovery of nuclear fusion as stellar fuel. The Sun is roughly halfway through its 10-billion-year hydrogen-burning phase—after which it will swell into a red giant and end as a white dwarf. He then discusses exoplanet detection, first via Doppler wobble (Mayor & Queloz, 1995) and transit methods, noting the surprising variety of planetary systems. Many feature Jupiter-like planets on eccentric close orbits, but among millions of systems, habitable planets likely exist. Future missions may image them directly.

Chapter 2: Life and Intelligence

Rees examines the likelihood of extraterrestrial life and intelligence, distinguishing two questions: how life originates (possibly near-inevitable or a fluke) and whether simple life evolves into intelligence (possibly far rarer). Earth’s long gap between simple and complex life—nearly 3 billion years—suggests severe barriers to complexity. He discusses Mars exploration, exotic habitats (neutron stars, interstellar clouds), and Fermi’s paradox. SETI searches remain worthwhile despite long odds. Even if life is unique to Earth now, the Sun’s remaining lifespan and the cosmos’s far longer future leave vast time for life to spread, making space habitat development an insurance policy for humanity’s potential.

Chapter 3: Atoms, Stars, and Galaxies

Rees traces how spectroscopy revealed that stars are made of the same elements as Earth, overturning Comte’s pessimistic claim that stellar composition would remain unknowable. Cecilia Payne’s 1925 thesis established that hydrogen and helium dominate stellar composition (98% of the Sun’s mass). The chapter’s core argument is stellar nucleosynthesis: heavier elements are forged inside stars and expelled via supernovae, recycling gas through successive stellar generations. Fred Hoyle’s pivotal prediction—that carbon nuclei must possess a specific resonant energy for three helium nuclei to combine—demonstrated both the success and fine-tuning of nuclear physics; altering the nuclear force by just 1–2% would eliminate carbon. Gravity’s extreme weakness (10³⁶ times weaker than electromagnetism) explains why stars must contain ~10⁵⁷ atoms and live billions of years—enabling complexity and evolution.

Chapter 4: Extragalactic Perspective

Galaxies are the fundamental building blocks of the large-scale universe, yet they remain less understood than stars. Rees describes how galaxies cluster hierarchically—into groups, clusters, and superclusters—but the universe is smooth on scales larger than ~200 million light-years. This large-scale uniformity makes cosmology tractable. Hubble’s law reveals an expanding universe with no privileged center. Rees surveys advances in telescopic power—from Keck and the VLT to the Hubble Space Telescope—and the opening of non-optical windows (radio, X-ray) that revealed energetic phenomena like black hole jets. The Hubble Deep Field images confirm large-scale uniformity and allow direct observation of the distant past. Cosmology is simpler than biology: extreme conditions reduce complexity, making stars simpler than insects.

Chapter 5: Pregalactic History

Rees recounts the Big Bang’s evidence and pregalactic cosmic history. Lemaître’s “primeval atom” and Gamow’s nucleosynthesis calculations preceded the decisive 1965 discovery of the cosmic microwave background by Penzias and Wilson. In the first few minutes, 23% of hydrogen fused into helium with traces of deuterium and lithium, but no heavier elements emerged. The CMB originates from when the universe became transparent (~300,000 years), after which darkness prevailed until the first stars. Dark matter—five to ten times more abundant than visible matter—is demonstrated by galaxy rotation curves, cluster dynamics, and gravitational lensing, yet its nature remains unknown. Gravity amplifies tiny initial density fluctuations (Q ≈ 10⁻⁵) into galaxies and clusters, confirmed by COBE’s detection of CMB temperature anisotropies. Rees expresses 99% confidence in Big Bang extrapolations back to ~1 second, reserving 1% for unknown physics before that era.

Chapter 6: Black Holes and Time Machines

Black holes are objects so completely collapsed that gravity has overwhelmed all other forces, permitting no escape—not even for light. Rees traces their conceptual history from Zeldovich and Novikov’s “frozen star” to Wheeler’s 1968 coining of “black hole.” Observational evidence includes stellar-mass black holes and supermassive ones in galactic centers (2.6 million suns in ours, over a billion in others). Paradoxically, black holes are among the best-understood objects: the Kerr solution exactly describes them using only mass and spin. An observer orbiting a rapidly spinning hole could “fast-forward” through future time due to extreme gravitational time dilation. On backward time travel, Gödel found general relativity permits closed timelike curves; wormholes would require exotic negative-pressure material. Rees entertains Novikov’s “chronology protection” argument—that physical laws constrain time loops—while noting that even a working time machine couldn’t send travelers back before its own construction date.

Part II — The Beginning and the End

Chapter 7: Deceleration or Acceleration?

Rees opens with the 1999 Cornwall solar eclipse, using it to distinguish prediction from understanding—Babylonians predicted eclipses without physical insight, while Halley grounded forecasts in Newtonian mechanics. The universe’s fate hinges on whether cosmic expansion decelerates enough to reverse. Ordinary atoms contribute only 4% of critical density; adding dark matter reaches ~0.3—insufficient for recollapse. The 1998 Type 1A supernova results stunned cosmologists: expansion appears to be accelerating, implying a cosmic repulsion. Einstein’s cosmological constant, once his “biggest blunder,” now seems prescient. Vacuum energy has negative pressure, producing antigravity—yet theoretical expectations overshoot the observed value by 120 orders of magnitude. An alternative, “quintessence,” posits a diluting dark-energy fluid. The concordance model: ~4% ordinary atoms, ~30% dark matter, ~66% dark energy—an extraordinary reversal from earlier assumptions.

Chapter 8: The Long-Range Future

In five billion years the Sun dies; eventually the Local Group’s galaxies merge into one system of aging stellar remnants. Farther ahead, rare stellar collisions light up dead galaxies, and gravitational radiation slowly erodes all orbits. Even black holes evaporate via Hawking radiation—stellar-mass holes in 10⁶⁶ years, supermassive ones by 10¹⁰⁰ years. Rees recounts Dyson’s 1979 argument that life could process infinite information with finite energy by using ever-lower-energy quanta—thinking ever more slowly but exhausting no limit. Two subsequent developments darken this optimism: protons likely decay, eroding stellar remnants within ~10³⁵ years, and accelerating expansion means distant galaxies redshift beyond the horizon, imposing hard complexity limits. Wild-card scenarios include quintessence decaying into bubbles of renewed activity, metastable vacuum undergoing catastrophic phase transition, and strangelet contagion from accelerators. A Big Crunch could permit infinite happenings in finite time, offering a richer existential finale than eternal dilution.

Chapter 9: How Things Began: The First Millisecond

Rees traces the universe backward from the well-established one-second mark—where the recipe requires just four ingredients (matter/dark matter/radiation proportions, expansion rate, smoothness parameter Q, and atomic properties)—into the speculative ultra-early phases. By one second, kinetic and gravitational energies were balanced to one part in 10¹⁵; any significant deviation would have yielded a universe either collapsing too soon or expanding too fast for structure. The matter-antimatter asymmetry left roughly one extra quark per billion pairs—an asymmetry in the ninth decimal place on which our existence depends. Inflation theory addresses the fine-tuning problem: a brief exponential expansion could stretch a microscopic patch to encompass our observable universe, establishing flatness and seeding structure via quantum fluctuations. Rees notes Penrose’s skepticism and the “graceful exit” problem, while acknowledging inflation as the leading paradigm.

Part III — Fundamentals and Conjectures

Chapter 10: Cosmos and Microworld

Rees explores links between cosmic and microphysical scales. He opens with the striking idea that the universe’s net energy could be zero—gravitational negative energy canceling rest-mass energy—so a universe could arise at zero cost. He discusses Mach’s principle (whether inertia derives from cosmic mass distribution) and Dirac’s large-number hypothesis—that G might decrease over cosmic time—tested against evidence from planetary orbits, neutron-star binaries, distant-galaxy spectra, and the Oklo natural reactor, all constraining changes to less than one part in 10¹⁰ per year. Three spatial dimensions are biophilic: only in 3D do inverse-square forces yield stable orbits, and electron bound states become possible. Superstring/M-theory posits ten or eleven dimensions, most compactified; some extra dimensions might be detectable at accelerators. Rees cautions that even a complete fundamental theory would not explain emergent complexity—water’s turbulence, biological organization—as these require autonomous conceptual frameworks. He critiques the “theory of everything” label as misleading.

Chapter 11: Laws and Bylaws in the Multiverse

Rees confronts the fine-tuning problem: our universe’s recipe—expansion rate, Q ≈ 10⁻⁵, small lambda, nuclear force balances—seems exquisitely calibrated for complexity and life. He evaluates three responses: (1) Happenstance—a unique theory fixes everything, though Rees finds this unsatisfying, citing Leslie’s firing-squad analogy; (2) Providence—design arguments updated from Paley, now citing not biology but physics (carbon resonance, inverse-square stability), championed by figures like Polkinghorne; (3) Multiverse—our universe is one habitable domain in a vast ensemble, like finding a suit that fits in a large shop. Rees prefers (3) and defends it as scientific through a four-horizon argument: from current telescopic limits to causal horizon to never-observable regions of our Big Bang to entirely disjoint universes, with no sharp epistemological break. He outlines multiverse scenarios (eternal inflation, black-hole spawning per Smolin, extra-dimension separation per Randall-Sundrum) and how they might be tested—for instance, lambda is only 5–10 times below the galaxy-formation threshold, consistent with anthropic selection. Rees proposes that some “constants” may be local bylaws, not universal laws—arbitrary outcomes like snowflake patterns rather than fundamental dictates—drawing a parallel to Kepler’s mistaken insistence on circular orbits, later superseded by Newton’s deeper but more permissive theory.

Author: John Polkinghorne  |  Library: Newbooks

Preface

Polkinghorne explains the book’s central thesis: science and theology share significant “cousinly relationships” in their truth-seeking methods, contrary to the common view that they are chalk and cheese. He rejects “quantum hype”—facile transfers of quantum paradox to other disciplines—and instead employs paired discussions, each feature illustrated first by physics then by theology. He hopes theologians will engage more seriously with science and scientists will recognize theology’s rational scrupulosity. The book is dedicated to his late wife Ruth.

Chapter 1: The Search for Truth

Critical Realism in Science and Theology

Both science and theology are truth-seeking enterprises grounded in critical realism—acknowledging epistemic precariousness while claiming genuine access to truth. Polkinghorne draws on Michael Polanyi’s “personal knowledge” to show science involves skilled judgement within a community, not mechanical rules. Both disciplines require hermeneutic circles linking encounter with interpretation, though theology’s circle is more complex due to its diachronic, revelatory, and existential character.

Four Differences Between Theology and Science

Theology differs from science in four ways: its diachronic character (insight spread across centuries, requiring dialogue with the past); God’s initiative in revelation (versus the scientist’s initiative in experiment); the fragmentation of world faiths (versus science’s near-universal assent); and the existential demands of religious belief (versus the more detached character of scientific conviction). These differences make the defence of critical realism more subtle in theology but do not undermine it.

Five Points of Cousinly Relationship

Polkinghorne outlines five parallels between the development of quantum physics and Christology: (1) enforced radical revision (wave/particle duality and divine/human language about Jesus); (2) periods of unresolved confusion (1900–1925 physics; the NT without systematic theology); (3) new synthesis and understanding (quantum theory; Trinitarian and Chalcedonian formulations); (4) continued wrestling with unsolved problems (the measurement problem; apophatic limits of theological language); (5) deeper implications (the EPR effect; Moltmann’s crucified God and theodicy).

Chapter 2: Comparative Heuristics

Techniques of Discovery: Experience and Understanding

Physics advances through creative interplay between experiment and theory—Einstein’s general relativity validated by Mercury’s perihelion, string theory’s current speculative phase lacking experimental discipline. Theology has “Christology from below” (grounded in historical evidence) and “from above” (conceptual coherence using philosophical tools). Neither discipline progresses through pure empiricism or pure speculation; both require disciplined interaction between assessed experience and imaginative interpretation.

Defining the Problem: Critical Questions

Quark theory succeeded by asking two sharp questions in sequence: first taxonomic order among particles, then the structural reality of quarks confirmed by deep inelastic scattering despite quarks never being observed in isolation. Christology asks three critical questions: Was Jesus resurrected? Why did the first Christians use divine language about him? What was the basis for their experience of transforming power? Functional or inspirational Christology fails to answer these; only incarnational understanding does justice to the New Testament witness.

Expanding Horizons: New Regimes

Phase transitions—such as superconductivity discovered by Kamerlingh Onnes in 1911—demonstrate that new physical regimes require new concepts while underlying laws remain consistent. Miracles, particularly the resurrection, are theological analogues: a new regime requiring new understanding, not a capricious “celestial conjurer” trick. The resurrection is best understood as a “sign” opening a window into deeper divine reality, analogous to superconductivity revealing deeper structure beyond Ohm’s law.

Critical Events of Particular Significance

Compton scattering in 1923 clinched the particle-like behaviour of light, dispelling all doubt. The resurrection is the analogous critical event for Christology. Polkinghorne examines the evidence: the enigmatic character of the appearance stories (difficulty of recognition, strange silence of Scripture, absence of future-hope themes), the empty tomb (women as witnesses despite their legal unreliability, the absence of secondary burial), the shift of the Lord’s Day to Sunday, and the transformation of frightened deserters into bold proclaimers.

Chapter 3: Lessons from History

Growing Recognition of Deeper Significance

In physics, Planck’s quantum hypothesis and Bohr’s model evolved through successive refinements into full quantum theory by 1925–26, demonstrating coherent growth in conceptual understanding. Christology followed a parallel trajectory: Jesus’ own self-understanding (Abba, Christ, Son of Man)—none intrinsically divine—developed through the early Church’s use of “Lord” and Old Testament imagery (second Adam, Wisdom, Logos in John’s Prologue), culminating in the Chalcedonian definition. Both fields discovered significance far greater than originally apparent.

Collateral Developments: Waves and Spirit

The concept of waves evolved from directly perceptible sea and sound waves, through Maxwell’s electromagnetic waves and the discredited luminiferous aether (abolished by Einstein’s special relativity), to Schrödinger’s abstract probability waves—an indispensable concept whose realistic interpretation matured beyond naive reification. The concept of Spirit followed a parallel arc: from Genesis’ ruach hovering over chaos, through prophetic bestowal, Pentecost, Paul’s diverse gifts and personal intercession, John’s Paraclete, to the fourth-century recognition of the Holy Spirit as the Third Person of the Trinity. Both concepts were preserved while their interpretation grew subtler.

Tides of Fashion

Relativistic quantum theory cycled through popularity and neglect: Dirac’s initial discoveries, infinities crisis, S-matrix theory as a leaner alternative, and gauge theory’s eventual resurgence. Christology followed a parallel arc: the first quest (Reimarus, Strauss), then rejection (Kähler, Schweitzer’s devastating critique showing liberal lives of Jesus reflected their authors’ era), Bultmann’s demythologisation, and the new quest’s return to historical foundations. Both disciplines had to return from fashionable substitutes to their foundational roots.

The Role of Genius

Exceptional individuals at propitious moments shaped both fields irrevocably. Heisenberg, Schrödinger, and Dirac each brought distinctive perspectives to quantum theory in the mid-1920s, founding the discipline through sheer creative insight. Analogously, Paul, John, and the writer to the Hebrews provided the deepest theological reflections in Christianity’s first generation, establishing conceptual frameworks that shaped all subsequent thought. Both cases demonstrate irreducible dependence on gifted minds seizing their moment.

Living with Unresolved Perplexities

Neither quantum physics nor theology has resolved its deepest problems. Physics lives with the measurement problem, difficulties combining quantum theory with general relativity (string theory’s untestable speculations), and quantum-chaos incompatibility. Theology faces the problem of evil: the free-will defence addresses moral evil, while the free-process defence suggests physical evil is the shadow side of a creation allowed to “make itself.” Most profoundly, the Christian God is the crucified God—a fellow sufferer, not a detached spectator. Both disciplines must live constructively with unresolved perplexity.

Chapter 4: Conceptual Exploration

Progressive Theoretical Development: From Models to Theory

Physics uses phenomenological models (Bohr’s atom, nuclear “cloudy crystal ball” model) that are eventually replaced by deeper unified theories (quantum field theory, QCD). Sometimes progress comes through radical conceptual re-evaluation, as with Einstein’s relativity. Christology follows the same pattern: adoptionism (God adopting a worthy man) proved inadequate; kenotic Christology (Philippians 2) and Irenaeus’s argument that salvation requires both true divinity and true humanity pushed understanding deeper. The New Testament titles are like phenomenological models; Nicene homoousios and Chalcedon’s “two natures in one person” are like fundamental theory—though Polkinghorne concedes Chalcedon resembles pre-1925 physics, holding paradox without full theoretical resolution. Apophatic theology and Baillie’s “central paradox” of grace and free will mirror physics’ acceptance of irreducible mystery.

Indefiniteness: A Cloud of Unknowing

Quantum field theory resolved wave/particle duality through ontological flexibility: indefinite particle number in wave-like states allows entities to be neither simply waves nor simply particles. Theology can take heart from this. Chalcedon’s less specifically articulated formula accepts a degree of mysterious indefiniteness analogous to quantum indefiniteness—refusing to reduce Christ’s person to a neat logical scheme just as quantum theory refuses to force entities into classical categories.

Toys of Thought: Thought Experiments

Einstein’s thought experiments against Bohr clarified quantum principles through conceptual pressure rather than laboratory work. Theology employs eschatological pictures (Revelation 21–22) as thought experiments exploring the coherence of Christian hope—not literal maps or timetables, but disciplined imaginative probes of whether faith’s promises are internally consistent.

Major Revision: Determinism and Divine Temporality

Physical determinism has been overturned by quantum theory and chaos theory, disproving the clockwork universe and opening conceptual space for ontological openness consistent with divine action and human agency. Polkinghorne parallels this with a major theological revision: the classical atemporal view of God (Boethius, Aquinas, Calvin) is being revised toward dipolar views where God genuinely engages with temporal process. Three considerations support this: science reveals a world of true becoming; scripture depicts God involved in history; and divine love requires immanence in time, not merely distant sovereignty.

Grand Unified Theories: GUT and the Trinity

Physics pursued unity from Galileo’s identification of celestial and terrestrial physics, through Newton’s universal gravity and Maxwell’s electromagnetism, to Weinberg-Salam electroweak theory and the ongoing quest for grand unification (string theory’s speculative reach remains untested). Trinitarian theology pursued analogous unification: the economic Trinity (God known as Father above, Son alongside, Spirit within) led to the immanent Trinity. Modalism and tritheism were rejected; Greek Fathers developed perichoresis and the subtle hypostasis-ousia distinction. Crucially, both fields discovered deep relationality: the Trinity’s “God is love” and physics’ entanglement and spacetime-matter coupling confirm reality is fundamentally relational. Polkinghorne concludes that the true “Theory of Everything” is trinitarian theology.

Chapter 5: Cousins

Biological Homologies as Analogy

Polkinghorne opens by drawing on comparative anatomy: biological homologies are explained either by common ancestry or by convergent evolution toward structures that are both advantageous and accessible. Simon Conway Morris’s work on convergent evolution—where eyes, for instance, evolved independently multiple times—suggests that the possibility-space of viable structures may be more constrained than assumed. He uses this dual explanation as an analogical lens for the cousinly kinship between science and theology.

Common Ancestry: Science Born from Christian Thought

The first explanation traces modern science to its birthplace within medieval Christian intellectual culture. The doctrine of creation—a freely created yet orderly world—encouraged the expectation of deep, discoverable order that required observation and experiment, not pure reason alone. This theory-experiment synthesis, pioneered by Galileo, drove the scientific revolution. Early scientists like Galileo and Newton saw no conflict between the “two books” of Scripture and Nature. The parting of ways came in the mid-18th century when triumphalist claims for the sufficiency of scientific method alone displaced theology, though notable scientists like Faraday, Maxwell, and Kelvin remained devout.

Deep Underlying Forms: The Logos Doctrine

The second explanation appeals to the Logos doctrine as the deep structure linking science and theology. John’s Gospel identifies the Word (Logos)—through whom all things were made—with the incarnate Christ. Colossians 1:16–17 identifies Christ as the one through whom all things are created and in whom they cohere. The Logos also enlightens everyone (John 1:9), which Polkinghorne connects to the philosophical endorsement of critical realism. The cousinly relationships explored throughout the book derive from the universe being a true cosmos created through the divine Word.

Implications and Conclusion

Because the cosmos originates in the divine Logos, religious believers should welcome all truth including scientific truth, and scientists pursuing understanding to its fullest will find themselves drawn toward religious belief—the search for the Logos. Polkinghorne concludes that the cousinly relationships between science and theology find their “most profound understanding in terms of that true Theory of Everything which is trinitarian theology.” The deep rational order and relationality manifest in the physical world reflect the character of the trinitarian God whose deepest reality is perichoretic love.