Book Review: The Character of Physical Law

ByGeorges Lteif

I. About This Book

Title

The Character of Physical Law

Author

Richard D. Feynman

First Published

1965

Edition

First

Pages

168

II. Who Should Read “The Character of Physical Law“

The Character of Physical Law is a popular science book for the busy. Deeply insightful, brilliant, and wastes no time on side stories, anecdotes, or unrelated topics.

It is also very different from most other popular science books that abound in bookstores. It has a very familiar storyline that starts on the shores of ancient Greece and goes all the way through Galileo and Newton’s time, then into the modern age of physics, where we find Relativity Theory and Quantum Mechanics. The Character of Physical Law is a book about the common principles of all physical laws, what makes them what they are, how they are discovered, and their relationship with mathematics and nature.

The Character of Physical Law is highly recommended for all popular science readers.

III. What Topics Does “The Character of Physical Law” Cover?

There is also a rhythm and a pattern between the phenomena of nature which is not apparent to the eye, but only to the eye of analysis; and it is these rhythms and patterns which we call Physical Laws. What I want to discuss in this series of lectures is the general characteristic of these Physcial Laws; this is another level, if you will, of higher generality than the laws themselves.

— Richard Feynman, The Character of Physical Law

The Character of Physical Law consists of seven lectures that Dr Feynman gave at Cornell University in 1964.

  • Lecture 1 –The Law of Gravitation, an Example of Physical Law.
  • This first chapter takes the reader on the journey of discovery of the Law of Gravity, from Kepler to Galileo, Newton, and Einstein. You might think you have heard this story many times, but here, it’s different. It deviates significantly from the most popular science writers’ descriptive approach, as it does not enunciate a principle and tries to explain it using logic or experimental data. Feynman’s text places the reader in the scientist’s mind and walks them on the journey of discovery.
  • Lecture 2 — The Relation of Mathematics to Physics.
  • Probably the most novel, insightful, and brilliant of all seven chapters, this one discusses how mathematics relates to physics and reality. Countless famous science writers took a shot at this particular question, but I think Feynman’s explanation was the most lucid. Here, Feynman explains two ways of finding new laws. The first, which he calls the Greek method, is where we always start from axioms and make our way through to theorems – safe but tedious. The second is what he calls the Babylonian method, which refers to how Babylonians taught science by having students go through many examples until they discovered the general rule.
  • Feynman believes the Babylonian method offers more paths from one theorem to another instead of the more restrictive path that always starts with the axioms.
  • Lecture 3 — The Great Conservation Principles.
  • This chapter discusses conservation laws, which are conventional topics, although this time illustrated in Feynman’s style. It explains the utility of conservation laws like energy, charge, or momentum conservation.
  • Lecture 4 — Symmetry in Physical Laws.
  • Yet another tour de force, explaining why spacetime is not space and time but a single whole. It also explains why translational symmetry in spacetime is between left and right and past and future. In this chapter, Feynman covers all sorts of symmetries: translational, rotational, matter and antimatter, and reflectional symmetry, which appears to be crucial for the development of life as we know it.
  • Lecture 5 — The Distinction of Past and Future.
  • This is the famous discussion on entropy and the second law of thermodynamics, although the word entropy appears only once in the chapter. One crucial idea described in this chapter, which, like many others, was masterly, was the notion of energy useability in contrast to availability and how it relates to temperature and irreversibility in some physical processes.
  • Lecture 6 — Probability and Uncertainty, The Quantum Mechanical View of Nature.
  • Having read QED Feynman’s famous lectures on Quantum Electro-Dynamics, I found this one to have quite similar content and style. It primarily focuses on the double-slit experiment, the go-to experiment for introducing quantum mechanics.
  • Lecture 7 — Seeking New Laws.
  • This chapter deals with how scientists discover new laws and is one of the most beautiful in the series. It explains how scientists solve complex problems, where the methodology is not always as organized and solid as we think. Complex problem-solving at one time was about marrying observation with theory (that gave us Newton’s Law of Gravity), at other points was resolving paradoxes (Einstein’s Special Theory of Relativity), or now filling gaps in the theory when, for example, we observe new, unexpected particles in high energy accelerators.

IV. Themes

Central Themes of “Feynman Lectures on Computation”

  • Physical Law
  • Scientific Discovery
  • The Law of Gravitation
  • Symmetry in Physics
  • Double Split Experiment
  • Crash investigation
  • The Nature of Spacetime
  • Quantum Mechanics
  • Mathematics and Physics
  • Conservation Principles
  • Einstein, Newton, Kepler, Galileo, Bohr

V. Feynman’s Writing Style

Imagine an enormous […] checkerboard. The actual operation of any one step is not mathematical – or it is very simple in its mathematics. But you could imagine on an enormous board, with lots and lots of pieces, some analysis of the best moves […] might be made by a deep kind of reasoning. […] That then becomes mathematics, involving abstract reasoning.

— Richard Feynman, The Character of Physical Law

Feynman is famous not only for his contributions to science, which led to his 1965 Nobel Prize win jointly with Julian Schwinger and Shin’ichirō Tomonaga, but also for being an exceptionally talented teacher and popularising science.

The Character of Physical Law was delivered in the same style as Feynman’s other lectures. Lucid, bright, engaging, and insightful, it demonstrates Feynman’s unique capability of explaining a complicated topic to a mathematical non-expert.

Unlike many other popular science books, where the author is either not thoroughly familiar with the topic or has a dry style, leaving the reader wanting more, Feynman’s lecture does not shy away from difficult questions, such as the question of “spooky action at a distance.”

This lecture was created in Feynman’s style. It focuses solely on physics and is, therefore, quite enjoyable for the busy reader.

VI. Accessibility of The Character of Physical Law

The text contains very few equations familiar to most people (such as Newton’s law of gravitational attraction). It also has numerous diagrams that work nicely with the text.

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