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Hello!
I am currently reading the second edition of Callen's Thermodynamics and an Introduction to Thermostatistics, and I have a question regarding Callen's definition of quasi-static. On page 96, Callen says:
Consider an arbitrary curve drawn on the hypersurface of Fig. 4.3*, from an......

I am a retired Physics prof. and Entrepreneur who has just joined. My work focus was applied physics, plasma and semicondcutor. I am now interested in a much broader field from philosophy to fundamental physics, metaphysics. I was hoping this forum might...

I've been told this is an extension of the Ehrenfest paradox, which is interesting but not explanatory.
Gedankenexperimenten: take any object and rotate it. Lets use a disc for simplicity, but by extension the question applies to any relative motion. The center of the disc is stationary......

Though experiment: imagine yourself floating above one of the poles of the earth. Since I'm in the Northern Hemisphere I will use the North pole. Looking down at Noon Greenwich time, the sun is directly above Greenwich.
Now freeze the tableau and imagine yourself as an infinitely fast......