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It's a blog! Mainly of book reviews.

Ack-Ack Macaque

Progress:
249/792 pages

Introduction to Topology

Progress:
10/224 pages

Isaac Newton

Progress:
20/289 pages

Basics of Plasma Astrophysics

Progress:
58/250 pages

Ursula K. Le Guin: The Complete Orsinia: Malafrena / Stories and Songs (The Library of America)

Progress:
454/700 pages

A Student's Guide to Lagrangians and Hamiltonians

Progress:
7/180 pages

Complete Poems, 1904-1962

Progress:
232/1102 pages

The Complete Plays and Poems

Gravitation (Physics Series)

Progress:
48/1215 pages

I Am a Cat

Progress:
410/638 pages

Interesting errors and confusions in Chapter 3:Conservation of energy: Heisenberg states that initially this was believed to be true only statistically for quantum systems but in fact turned out to be exactly true always. This is not correct; conservation of energy can only be said to hold to the accuracy given by - fanfare! - The Heisenberg Uncertainty Principle! One of the bizarre consequences of this is the phenomenon of quantum tunneling, which was unknown at the time of publication.

Heisenberg states that quantum mechanical experiments consist of three parts, an initial set up in terms of classical physics, an unobservable part only describable in terms of what we would now call the probability wave-function, and a measurement only describable in terms of classical physics. Only the middle part of this is correct; it is entirely possible to describe an experimental set-up in quantum terms and also the measurement of the result in quantum terms, too. (The middle bit is indeed not describable in any normal sense.) Take the photon double-slit experiment. The emission of the photons can be described quantum mechanically *but so can their reception at the detector* if you use photo-multiplier detectors, for example.

Ah! I hear you cry, but the *real observation* is by the human eye, when the flash from the photo-multiplier hits the retina!

Sorry - the optic nerve is a receptor of quanta, too. The whole system is describable quantum mechanically.

Heisenberg then goes on to more or less follow my argument in a vague way. (It's enormously easier to make it precise in the light of half a century's technological advances.)

And here's something really important that we agree on. The *human observer* is not in any way an *essential* part of the system. The idea that the entire universe stopped being just a cloud of probabilities the day a sufficiently astute observer appeared is not in any way required by or implicit in the Copenhagen Interpretation.

...and we're only about 1/6th the way through...

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