why was Planck`s theory of balckbody radiation considered to be revolutionary?

Answer 1

It wasn't initially.

It was a trick to make a classical theory of blackbody radiation work better. Wein's law worked well for low frequencies, but was disastrous for high frequencies predicting that a body would emit higher and higher energies the higher the frequency.

Planck found that he could get a better fit with experiment by assuming that the energy of the particles emitting light was restricted to resonance of a fundamental oscillator frequency. This was close to Weins trick - treating black bodies as calssical cavity resonators - and Planck regarded it simply as a bit of mathematically trickery that made the results work.

However, with the proposal by Einstein 5 years later that light was actually emitted in packets in order to explain the photoelectric effect (Planck still assumed light was emitted continuously), it formed the basis of quantum mechanics.

Answer 2

Before his theory, it was felt that energy was transmitted evenly across the spectrum. This ran into trouble when it was realized that the visible spectrum formed a small part of the overall and if the old theory was followed logically, the enegy would escape almost instantly, mostly in non-visible portions of the spectrum. His theory accounted for the different behavior by declaring that no energy could be transmitted (or absorbed) until a whole quanta was accumulated and the size of the quanta depended on the wave length.

Answer 3

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