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What does Max Planck mean in this quote?

  1. Sep 6, 2010 #1
    out of "The Origin and Development of the Quantum Theory" given somewhere in the 1920's. If you type the title in google, you can read a html copy

    If you type "max planck history.mcs.st development quantum theory" into google, the 2nd hit is a free html version of the text (it's not long)

    As a fun historical sidenote, the following quote seems amusing in hindsight:
  2. jcsd
  3. Sep 7, 2010 #2
    He means that his constant is the same for all observers in the universe.

    Planck liked the idea that alien intelligences anywhere in the universe would all agree on the value of this fundamental constant, there's an entertaining essay which highlights Planck's obsession with Absolutes by J Heilbron in the collection "Quantum Theory at the Crossroads" (Evans & Thorndike, Spinger 2007)
  4. Sep 7, 2010 #3
    Hm, but the way he says it, it's like he's implying relativity made us believe our physical constants were less "constant" than we thought, but isn't it quite the opposite? The theory of relativity says all constans in the laws are constant (unlike the speed of light was thought to be before the theory of relativity)

    Then again it does make me think: imagine you're looking at an object passing you and thus being contracted length-wise: if you were to measure his "planck's constant", would you get the same as "your own" constant?
  5. Sep 7, 2010 #4
    That's an issue with theories predicting a minimal length scale (eg planck length), since then, as you point out, you have to specify which reference frame the length is defined in. (You can cheat and propose it as a separate postulate, eg Doubly special relativity)

    But I think Planck was just proud that he had discovered a universal invariant constant just like the speed of light (and perhaps the Gravitational Constant) which seemed to fix some properties of the microscopic in exact discretised quantities, at a time when relativity of the observer was such an important new idea in macroscopic physics.
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