Did Planck view light as a particle or a wave?

[6021023]

Did Planck think that light was a particle or a wave?

 

[alxm]

AFAIK Planck, like all his contemporaries, believed light was an electromagnetic wave (which it really is, the way it's seen now is that it's just that electromagnetic waves in general don't behave quite like how we thought).

Now, the thing about Planck's radiation law is that it implies light was emitted in discrete quanta of energy (c.f. the $$h\nu$$ term in Planck's law with the $$\Delta E$$ in the Boltzmann distribution).

But (as opposed to how it often gets described) Planck did not actually put any deeper import on that fact. He didn't really assume there were photons, or that energy/light was quantized (rather that, the 'oscillators' as he called atoms/molecules, emitted light in quanta).

There's an http://physicsworld.com/cws/article/print/373" here that attempts to set the record straight on Planck's contributions.

 

[dmtr]

Did Planck think that light was a particle or a wave?

I think it was Einstein, who realized that light was made out of particles.

From the http://en.wikipedia.org/wiki/Planck%27s_law:

Planck made this quantization assumption five years before Albert Einstein hypothesized the existence of photons as a means of explaining the photoelectric effect. At the time, Planck believed that the quantization applied only to the tiny oscillators that were thought to exist in the walls of the cavity (what we now know to be atoms), and made no assumption that light itself propagates in discrete bundles or packets of energy. Moreover, Planck did not attribute any physical significance to this assumption, but rather believed that it was merely a mathematical device that enabled him to derive a single expression for the black body spectrum that matched the empirical data at all wavelengths.