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  • Are Theoretical Physicists Good Logicians?

    From Pentcho Valev@21:1/5 to All on Wed Aug 10 14:42:49 2022
    Let us see:

    James Hartle, Gravity: An Introduction to Einstein's General Relativity, p. 113: "If we accept the equivalence principle, we must also accept that light falls in a gravitational field with the same acceleration as material bodies." https://www.amazon.com/
    Gravity-Introduction-Einsteins-General-Relativity/dp/0805386629

    Paul A. Tipler, Ralph A. Llewellyn, Modern Physics: "A beam of light will accelerate in a gravitational field as do objects with rest mass. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2." http://web.pdx.edu/~pmoeck/
    books/Tipler_Llewellyn.pdf

    The proposition

    "Light falls in a gravitational field with the same acceleration as material bodies."

    true or false, will be the premise, and there are logical consequences that theoretical physicists may try to deduce. For instance, the following questions can be answered:

    1. Does the Pound-Rebka experiment confirm the premise?

    2. Is there gravitational time dilation?

    3. In the absence of gravitation, does the speed of light vary with the speed of the observer?

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    Pentcho Valev

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  • From Pentcho Valev@21:1/5 to All on Thu Aug 11 07:32:49 2022
    One of the following statements is a valid deduction from Einstein's 1905 two postulates; the other statement is, accordingly, non sequitur (does not logically follow from the postulates):

    (A) The moving clock lags behind the stationary one AS JUDGED FROM THE STATIONARY SYSTEM, and the stationary clock lags behind the moving one AS JUDGED FROM THE MOVING SYSTEM (symmetric time dilation).

    (B) The moving clock lags behind the stationary one AS JUDGED FROM BOTH SYSTEMS (asymmetric time dilation).

    Which statement, (A) or (B), is the valid deduction, theoretical physicists? The "peculiar consequence" in Einstein's text below is equivalent to (A) or to (B)? Is the "peculiar consequence" non sequitur?

    Albert Einstein, On the Electrodynamics of Moving Bodies, 1905: "From this there ensues the following peculiar consequence. If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the
    clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by tv^2/2c^2 (up to magnitudes of fourth and
    higher order), t being the time occupied in the journey from A to B." http://www.fourmilab.ch/etexts/einstein/specrel/www/

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    Pentcho Valev

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