The Nature of the Physical World

Summary

The Nature of the Physical World is Arthur Eddington's account, for general readers, of what relativity, thermodynamics and quantum theory had done to the picture of the physical world, and of what that picture leaves room for in human experience. It is substantially the Gifford Lectures he gave at the University of Edinburgh from January to March 1927, published in 1928 by Cambridge University Press and Macmillan. The library stores no text of the book and gives no quotations: although the work is now in the public domain in the United States, no verified transcription has been attached here, so the record describes it in its own words. The Introduction sets out Eddington's famous two tables: the familiar table of everyday life, solid, coloured and substantial, and the scientific table, mostly empty space sparsely scattered with electric charges moving at great speed. Physics, he argues, now deals only with the second, a world of symbols. Chapters I to III explain the downfall of classical physics, the special theory of relativity, and the relativity of simultaneity, with examples such as the shrinking of a moving rod and the slower clocks of a fast traveller. Chapter IV, The Running-Down of the Universe, gives the second law of thermodynamics the supreme place among the laws of nature, illustrates entropy as a measure of random shuffling, and introduces the phrase time's arrow for the one-way direction that entropy gives to time; it also offers the image of monkeys at typewriters to show how improbable an un-shuffling would be. Chapter V asks how the sense of becoming in consciousness relates to this arrow. Chapters VI and VII present Einstein's law of gravitation and its explanation as the curvature of space-time, and Chapter VIII considers man's place among the stars and the vastness of the universe. Chapters IX to XI explain the old and new quantum theory, Heisenberg's uncertainty principle and the building of the world out of relations. The last chapters turn to philosophy. Pointer Readings argues that physical science knows only the readings of instruments and their mathematical relations, not the intrinsic nature of what is measured; Reality suggests that the stuff of the world may be mind-stuff, known to us directly only in our own consciousness; Causation argues that the new indeterminism removes the physical objection to free will; and Science and Mysticism defends religious experience as a legitimate approach to an aspect of reality that physics, by its method, leaves out. The book was a best-seller and helped shape public discussion of science and religion between the wars.

Plot or Argument

• Introduction: The two tables

  The everyday table and the scientific table are contrasted; physics describes a shadow world of symbols rather than the familiar world.

• Chapters I-III: Classical physics overturned, relativity and time

  The failure of the ether and of absolute simultaneity, the Fitzgerald contraction, and the relative measurement of time and space by different observers.

• Chapters IV-V: Entropy, time's arrow and becoming

  The second law of thermodynamics as the supreme law, entropy as shuffling, the arrow of time, the running-down of the universe, and the consciousness of becoming.

• Chapters VI-VIII: Gravitation and man's place

  Einstein's law of gravitation, its explanation by the curvature of space-time, and the scale of the stellar universe.

• Chapters IX-XI: Quantum theory and world building

  Planck's quantum, Bohr's atom, the new quantum mechanics of Heisenberg and Schrodinger, the uncertainty principle, and how physics builds a world from relations.

• Chapters XII-XIII: Pointer readings and reality

  Science knows only measurements and their structure; the intrinsic nature of the world may be akin to mind.

• Chapters XIV-XV and Conclusion: Causation and mysticism

  Indeterminism and free will; the place of religious and mystical experience beside physical science; a closing summary of the argument.

Characters

• Albert Einstein, physicist

  Author of the special and general theories of relativity expounded in the early chapters.

• Werner Heisenberg, physicist

  Founder of matrix mechanics whose uncertainty principle Eddington explains.

• Niels Bohr, physicist

  Author of the quantum model of the atom discussed in the quantum chapters.

• Erwin Schrodinger, physicist

  Creator of wave mechanics, presented as part of the new quantum theory.

Lessons

• What physics measures

  Eddington's two tables and his chapter on pointer readings argue that physics describes the measurable structure of things, not what they are in themselves. This does not make science false; it marks its boundary. The lesson is to distinguish what a method can know from what it cannot.

  • In what sense is the scientific table real, and in what sense is the everyday table real?
  • What does Eddington mean by saying that science deals with pointer readings?
  • Does knowing the limits of a method make its results more or less trustworthy?

• The arrow of time

  In Chapter IV Eddington finds the direction of time not in the laws of motion, which run equally well backward, but in the growth of entropy. A shuffled pack does not unshuffle itself. He coined the phrase time's arrow for this one-way direction, and the idea remains central to physics and its philosophy.

  • Why can the laws of mechanics not tell past from future?
  • How does the shuffling of a pack of cards illustrate entropy?

• Freedom and the new physics

  Eddington argues in Chapter XIV that quantum indeterminism removes the claim that physics proves every human act predetermined. He does not say physics proves freedom, only that it no longer forbids it. Philosophers and scientists have disputed whether chance at the atomic level bears on human choice at all.

  • What did classical determinism seem to imply about human choice?
  • Is a choice made by chance any freer than one fixed by causes?
  • Why might Eddington's critics say he moved too quickly from physics to freedom?

• Science and the spiritual world

  In Science and Mysticism, Eddington, a Quaker, holds that the methods of physics are designed to leave out the inner life, and so cannot pronounce against religious experience. He presents mystical insight as a different approach to reality, not a rival theory of atoms. Readers have found the argument either liberating or too modest.

  • Why does Eddington think physics cannot be the whole account of reality?
  • What kind of evidence does he think religious experience provides?

Context

Between 1900 and 1927 physics passed through the quantum hypothesis, special and general relativity, Bohr's atom and, in 1925-27, the new quantum mechanics of Heisenberg, Schrodinger and Dirac, ending with the uncertainty principle of 1927. Eddington, already the leading British interpreter of relativity, gave his Gifford Lectures in the very months these results were being absorbed. The Gifford Lectures, founded by Lord Gifford's bequest, were devoted to natural theology, which encouraged him to draw out the philosophical and religious implications.

Composition

The lectures were delivered at the University of Edinburgh from January to March 1927; Eddington revised them for publication, adding material on the new quantum theory, and signed the preface in August 1928. The book appeared in 1928 from Cambridge University Press in Britain and Macmillan in New York, and went through many reprintings.

Reception

The book sold widely and, with James Jeans's popular works, made the new physics a public subject. Some reviewers and philosophers welcomed its idealist and religious conclusions; others, notably L. Susan Stebbing in Philosophy and the Physicists (1937), argued that Eddington drew philosophical conclusions his physics did not support, especially in the two tables and the argument from indeterminism to freedom. Its phrase time's arrow passed into general scientific use.

Comparisons

• einstein-relativity

  Einstein's own popular exposition of relativity covers the ground of Eddington's early chapters; Eddington adds thermodynamics, quantum theory and philosophy.

• heisenberg-physics-and-philosophy

  Both are Gifford Lectures by physicists drawing out the meaning of quantum theory; Heisenberg speaks as a founder of the Copenhagen view three decades later.

• poincare-science-and-hypothesis

  Poincare argued that science knows the relations between things, not the things themselves, a view close to Eddington's chapter on pointer readings.

• schrodinger-what-is-life

  Another physicist addressing a general audience, Schrodinger also uses entropy and ends with reflections on mind and self.

Quotes

For Students

A reading companion for classical Christian high school students. See the student guide.

Reading Guide

Watch for

• The two tables in the Introduction, and how the image returns in the later philosophical chapters.
• The illustration of a shuffled pack of cards and the phrase time's arrow in Chapter IV.
• How Chapter XII limits physics to pointer readings and their mathematical relations.
• The move in Chapter XIV from atomic indeterminacy to human freedom.
• Eddington's account of religious experience in Chapter XV.

Key terms and names

The two tables

Eddington's opening contrast between the solid table of experience and the mostly empty table of physics.

Entropy

A measure of the random element or shuffledness of a system, which the second law says always tends to increase.

Time's arrow

Eddington's phrase for the one-way direction of time, which he finds in the increase of entropy.

Pointer readings

The positions of needles on instruments; Eddington argues that all physical knowledge reduces to them and their relations.

Mind-stuff

Eddington's name for the unknown intrinsic nature of the world, which he suggests is akin to consciousness.

Gifford Lectures

Lectures on natural theology at Scottish universities, endowed by Lord Gifford; this book is Eddington's 1927 series.

Seminar Questions

1. Comprehension What are the two tables, and how do they differ?
2. Comprehension Why does Eddington give the second law of thermodynamics the supreme place among the laws of nature?
3. Comprehension What does Eddington claim the uncertainty principle changes about the old argument against free will?
4. Interpretation If physics knows only pointer readings, what does Eddington think fills in the rest of reality?
5. Interpretation Is Eddington right that the method of physics leaves out the inner life by design? What would follow if he is?
6. Interpretation Stebbing objected that the everyday table is not an illusion. How might Eddington answer her?
7. Big Question Can science and religious experience be two approaches to one reality, or must one finally absorb the other?

Faith Connections

• 2 Corinthians 4:18 (Scripture)

  The things which are seen are temporal, but the things which are not seen are eternal: Eddington's claim that physics gives the measurable structure of things but not their inner nature leaves room for the unseen.

• Psalm 102:25-27 (Scripture)

  The heavens shall wax old as doth a garment: the psalmist's contrast between a perishing creation and the unchanging God meets Eddington's running-down universe in Chapter IV.

• Augustine, Confessions XI (Church Fathers)

  Augustine's inquiry into what time is, and how the mind measures past, present and future, is an ancient companion to Eddington's chapters on time and becoming.

Logic and Rhetoric

Central argument: Physics describes the world only as structure revealed in measurements. Our one direct acquaintance with the inner nature of anything is our own consciousness. Therefore it is reasonable to think the underlying stuff of the world is akin to mind, and physics, by its method, cannot rule out freedom or religious experience. The new indeterminism removes even the old physical argument against free will.

Rhetorical device: extended analogy. The two tables of the Introduction turn an abstract claim about the limits of physics into a concrete everyday picture, which the later chapters on pointer readings and reality develop.

Debate: Resolved: that the discoveries of modern physics make belief in free will more reasonable than classical physics did.

Writing Prompts

Essay: Explain Eddington's argument from entropy to time's arrow in Chapter IV, and argue whether it shows that the direction of time is a physical fact or a fact about our knowledge.

Comparison with Physics and Philosophy: Eddington and Heisenberg both gave Gifford Lectures on the meaning of quantum theory. Compare how each uses the uncertainty principle and what each concludes about reality.

Medical Lens

The book contains no medicine, but its later chapters bear on the mind-body problem as it stood for psychiatrists and physiologists of the interwar period. Eddington argues that physics knows matter only as structure and that consciousness is the one place where we meet the intrinsic nature of anything; he also discusses whether the indeterminacy of atomic events could matter for processes in the brain. These are philosophical proposals, and their bearing on neuroscience was disputed at the time and since.

• Chapter XIII (Reality)

  Eddington proposes that the stuff of the world is of a mental character, known directly only in consciousness.

  Mind Body
• Chapter XIV (Causation)

  Discussion of indeterminism, the brain and free will.

  Mind Body

Creative Prompts

• Classroom

  Describe the desk in front of you twice, once as an ordinary person and once as a physicist, in the manner of Eddington's two tables.

• Essay

  Does the quantum uncertainty Eddington describes in Chapter XIV help the case for free will? Present his argument and the strongest objection.

• Dialogue

  Write a conversation between Eddington and L. Susan Stebbing about whether the everyday table is real.

Further Reading

• Space, Time and Gravitation, Arthur Eddington

• The Mysterious Universe, James Jeans

• Philosophy and the Physicists, L. Susan Stebbing

• Science and the Modern World, Alfred North Whitehead