Physics & Philosophy – Sir James Jeans (1943)


Physics & Philosophy – Sir James Jeans (1943)


Title: Physics & Philosophy

Author: Sir James Jeans

Publisher: Cambridge University Press, 1943. 3rd printing.

Condition: Hardcover, no dust jacket. Good. Some wear to cover, minor foxing to edges. Inscription to ffep. Text clean, binding tight. 222pp.

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About the book:


  1. What are Physics and Philosophy?
  2. How do we know? (Descartes to Kant; Eddington)
  3. The two voices of Science and Philosophy (Plato to present)
  4. The Passing of the Mechanical Age (Newton to Einstein)
  5. The New Physics (Planck, Rutherford, Bohr)
  6. From Appearance to Reality (Bohr, Heisenberg, de Broglie, Schrodinger, Dirac)
  7. Some Problems of Philosophy
  8. Index

About the author (from Wikipedia):

Sir James Hopwood Jeans  (11 September 1877 – 16 September 1946) was an English physicist, astronomer and mathematician.

One of Jeans’ major discoveries, named Jeans length, is a critical radius of an interstellar cloud in space. It depends on the temperature, and density of the cloud, and the mass of the particles composing the cloud. A cloud that is smaller than its Jeans length will not have sufficient gravity to overcome the repulsive gas pressure forces and condense to form a star, whereas a cloud that is larger than its Jeans length will collapse.

Jeans came up with another version of this equation, called Jeans mass or Jeans instability, that solves for the critical mass a cloud must attain before being able to collapse.

Jeans also helped to discover the Rayleigh–Jeans law, which relates the energy density of black-body radiation to the temperature of the emission source.

“The stream of knowledge is heading towards a non-mechanical reality; the Universe begins to look more like a great thought than like a great machine. Mind no longer appears to be an accidental intruder into the realm of matter… we ought rather hail it as the creator and governor of the realm of matter.” from The Mysterious Universe

What remains is in any case very different from the full-blooded matter and the forbidding materialism of the Victorian scientist. His objective and material universe is proved to consist of little more than constructs of our own minds. To this extent, then, modern physics has moved in the direction of philosophic idealism. Mind and matter, if not proved to be of similar nature, are at least found to be ingredients of one single system. There is no longer room for the kind of dualism which has haunted philosophy since the days of Descartes. —Addressing the British Association in 1934.