Hi all, I've just started reading upon quantum physics and came across Max Planck. I believe he was the one to state that the oscillating atoms or molecules that emit radiation could only occupy quantum states, whereby photons with energy according to E=hf are emitted when an atom changes from one quantised energy state to another. But, if Einstein has simply extended Planck's concept of quantization, are there differences between Einstein's and Planck's hypotheses? Is it that Einstein extended Planck's concept to electromagnetic waves, primarily to light, as a stream of photon? Or, are there no differences? Also, if we have come to model light as a stream of photons, would this support the particle nature of light? If so, photons are considered to be particles, right? Thank you, all!