Monday, February 13, 2012

Max Planck and Photon

Max Planck and Photon - a truly great man and a rather small thing.

The great man
Max Karl Ernst Ludwig Planck (1858 – 1947) was a German physicist who discovered quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of quantum theory, for which he received the Nobel Prize in Physics in 1918.

Max Planck Institute of Natural Sciences and Astrophysics carries his name.

The small thing, 1900
The central assumption behind his new derivation, presented to the DPG on 14 December 1900, was the supposition, now known as the Planck postulate, that electromagnetic energy could be emitted only in quantized form, in other words, the energy could only be a multiple of an elementary unit

E = hν

where h is Planck's constant, also known as Planck's action quantum (introduced already in 1899), and ν (the Greek letter nu, not the Roman letter v) is the frequency of the radiation. Note that the elementary units of energy discussed here are represented by hν and not simply by h.

Physicists now call these quanta photons,

and a photon of frequency ν will have its own specific and unique energy.

The amplitude of energy at that frequency is then a function of the number of photons of that frequency being produced per unit of time.

An even greater man?
At first Planck considered that quantisation was only "a purely formal assumption ... actually I did not think much about it..."; nowadays this assumption, incompatible with classical physics, is regarded as the birth of quantum physics and the greatest intellectual accomplishment of Planck's career (Ludwig Boltzmann had been discussing in a theoretical paper in 1877 the possibility that the energy states of a physical system could be discrete).

Further interpretation of the implications of Planck's work was advanced by Albert Einstein in 1905 in connection with his work on the photoelectric effect—for this reason, the philosopher and historian of science Thomas Kuhn argued that Einstein should be given credit for quantum theory more so than Planck, since Planck did not understand in a deep sense that he was "introducing the quantum" as a real physical entity.

Be that as it may, it was in recognition of Planck's monumental accomplishment that he was awarded the Nobel Prize in Physics in 1918.

Theological note
Let us keep in mind that neither Max Planck nor Albert Einstein invented photon.

God of Israel created it.

These two great men figured out what that thing called light is using very effectively the brains that God had given them.

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