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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeJul 5th 2012

    started an entry Planck’s constant with a remark on its meaning from the point of view of geometric quantization (and nothing else, so far).

    • CommentRowNumber2.
    • CommentAuthorUrs
    • CommentTimeMar 29th 2014

    Added Planck constant – Basic definition, just for fun. (And also since it’s a point rarely made explicit, simple as it is.)

    • CommentRowNumber3.
    • CommentAuthorTodd_Trimble
    • CommentTimeMar 29th 2014
    • (edited Mar 30th 2014)

    Am a little surprised that nothing (or barely anything) was said about the dimension of hh as a physical unit, as measured in (kg)m 2s 1(kg)m^2 s^{-1} or whatever. Is that considered too low-level?

    • CommentRowNumber4.
    • CommentAuthorUrs
    • CommentTimeMar 30th 2014

    It’s not too low level, no. Please add it if you have energy.

    • CommentRowNumber5.
    • CommentAuthorTodd_Trimble
    • CommentTimeApr 1st 2014

    Well, I had the time and energy (measured in joule-seconds?) to put in a little something about Planck’s constant as a physical constant, but it might be considered embarrassingly low-level. In which case, please feel free to jazz it up to suit taste.

    • CommentRowNumber6.
    • CommentAuthorThomas Holder
    • CommentTimeApr 1st 2014

    Mentioning the Planck scale there would give a peg to hang on a funny observation of John L. Bell in some version of ch.1. of his primer of infinitesimal analysis, namely that the infinitesimal neighborhood of 0 is akin to the Planck scale in that there the order-theoretic structure of the smooth line breaks down. I wonder whether more could be made of this observation. Unfortunately, I can’t give a more precise reference here, because I have this version in electronic form only, and it isn’t contained in the first print edition nor can I find a corresponding text on his homepage.

    • CommentRowNumber7.
    • CommentAuthorUrs
    • CommentTimeApr 1st 2014

    Thanks, Todd.

    I have moved your addition up to the top. Then I added an Idea-section which points to the various subsections.

    Will have to create an entry physical unit now.

    • CommentRowNumber8.
    • CommentAuthorUrs
    • CommentTimeJan 26th 2019
    • (edited Jan 26th 2019)

    added a brief History-comment just so as to link back to entries such a black body radiation and ultraviolet catastrophe

    diff, v15, current

    • CommentRowNumber9.
    • CommentAuthorTobyBartels
    • CommentTimeAug 12th 2020

    Names for \hbar

    diff, v17, current

  1. I updated the value of the constant to take into account new SI definitions. The kilogram is now defined in terms of hh, hence hh’s value is fixed exactly.

    diff, v18, current

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