May I know why is there a need to quantize photon? can't scientist single them out?
This is a very strange question.
You seem to forget history. We don't have the "need" to do anything. We only had to do something based on what Mother Nature tells us. Einstein just simply didn't wake up one day and said "I think, today, I'll just quantize photons for the hell of it".
I could easily ask you why do we need to describe light as a wave? Why do we need to quantize the electronic charge? Why do we need to have mass on fundamental particles, etc.. etc...
Pardon me please, I'm just recently exposed to this module and have absolutely no background knowledge of physics at all. I'm really confused about these new terms(or scientific jargons).
So Einstein didn't need, then preferably I can rephrase my question to : Why did he say photon come in packets or quantized them?
Because by doing that, which was inspired by Planck's Blackbody explanation, he could explain the photoelectric effect that could not be explained at that time via Maxwell Equations.
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