Planck Arriving at a Relation Between Energy and Frequency with h

[coca-cola]

Hello,

I have recently been reading some texts focusing on modern physics. Both include sections on Planck and how he arrived at the conclusion that energy is not continuous. However I am confused as to what conditions inspired him to make this leap. I am aware of the Ultraviolet Catastrophe, but is that what led Planck to his epiphany or was it some other conflict in his work?

Thanks!

 

[UltrafastPED]

Here is a good summary: http://physics.about.com/od/quantumphysics/a/blackbody.htm

 

[Jano L.]

Both include sections on Planck and how he arrived at the conclusion that energy is not continuous.

Beware, that is not what Planck thought! True, in his first papers he used integer numbers to calculate energy changes, similarly to some Boltzmann's statistical calculations. But then it was just a mathematical assumption that allowed them to do calculations.

Planck did not believe that the radiation was really made of such quanta, because that would contradict the EM theory. In his later work on the thermal radiation he was able to decrease the role of the quanta of energy only to the process of emission by the matter, all else remaining continuous as ever.

See the paper

Stephen G. Brush, Cautious revolutionaries: Maxwell, Planck, Hubble, Am. J. Phys. 70, 119 (2002)

http://dx.doi.org/10.1119/1.1427310

From the paper:

͓Emphasis As the historian of science Olivier Darrigol points out, the
last sentence ‘‘leaves no reason for doubt’’: ‘‘the energy of a
single resonator was not thought to be restricted to multiples
of ␧.’’22 Planck was not actually proposing quantization of
the resonator energies as a physical hypothesis, but only as a
mathematical approximation to allow the use of a combina-
torial formula for W: the number of ways of distributing
something must be an integer. This approximation allowed
him to derive the empirically correct distribution function for
blackbody radiation and, along with it, the new fundamental
constant h; but it did not directly establish the validity of a
quantum hypothesis.

The great place to learn about Planck's actual thinking on this problem is also his book

M. Planck, The theory of heat radiation, P. Blakiston's Son & Co., 1914

Only in his later years, it seems he became more favorable of the idea of real existence of quanta of radiation.