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Robert "The Bobby Yaga" McNees @mcnees.bsky.social · 14/12/2024

The results of Planck’s December 14th lecture were submitted to Annalen der Physik a few weeks later, on January 7th, and published not long after that. An English translation can be found in Dirk ter Haar’s “The Old Quantum Theory,” but the version I’ve linked in the past has gone offline. (12/n)

The title and intro read:

On the Theory of the Energy Distribution Law of the Normal Spectrum
M. Planck
Berlin
(Received 1900)

English translation from "The Old Quantum Theory," ed. by D. ter Haar, Pergamon Press, 1967 p. 82

GENTLEMEN: when some weeks ago I had the honour to draw your at- tention to a new formula which seemed to me to be suited to express the law of the distribution of radiation energy over the whole range of the normal spectrum , I mentioned already then that in my opinion the usefulness of this equation was not based only on the apparently close agreement of the few numbers, which I could then communicate, with the available ex- perimental data, but mainly on the simple structure of the formula and especially on the fact that it gave a very simple logarithmic expression for the dependence of the entropy of an irradiated monochromatic vibrating resonator on its vibrational energyà This formula seemed to promise in any case the possibility of a general interpretation much rather than other equa- tions which have been proposed, apart from Wien's formula which, however, was not confirmed by experiment.

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Robert "The Bobby Yaga" McNees @mcnees.bsky.social · 14/12/2024

Something that isn’t as widely known, is that “h” is not the only fundamental constant that was introduced during Planck’s presentation to the German Physical Society #OTD in 1900. (13/n)

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Robert "The Bobby Yaga" McNees @mcnees.bsky.social · 14/12/2024

Planck was investigating emission and absorption by blackbodies, so he needed a way to relate energies and temperatures. Thus, he had to introduce what we now refer to as “Boltzmann’s constant.” 🧪 ⚛️ 🎢 (14/n)

$The passage reads: After the stationary energy distribution is thus determined using a con- stant h, we can find the corresponding temperature 0 in degrees absolute^{2} using a second constant of nature k = 1.346 × 10⁻⁶ erg • degree⁻¹ through the equation \frac{1}{\vartheta} = k \frac{d \ln R_0}{d E_0} The product k In• R_0 is the entropy of the system of resonators; it is the sum of the entropy of all separate resonators.$

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