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All he needed was quantised oscillators in the walls, the quantisation of any radiation that could be found inside the cavity would follow automatically. This has some relevance for suggesting one reason why all bits of light you might find anywhere (e.g. not just inside a cavity) would still be quantised: If every bit of light (anywhere) has it origin ultimately in a transition that happened in an atom, then the source of all e-m radiation is suitably quantised, so all the radiation you will find will automatically be suitably quantised.
Some e-m radiations come from molecular activities. Some others come from macroscopic mechanical vibration.
Yes, you can derive the blackbody spectrum by assuming radiation is quantised but you just don't have to and historically it does not look like Planck made that assumption. All he needed was quantised oscillators in the walls, the quantisation of any radiation that could be found inside the cavity would follow automatically.
Quote from: hamdani yusuf on 11/06/2023 11:27:45Some e-m radiations come from molecular activities. Some others come from macroscopic mechanical vibration.Has em radiation from a macroscopic vibration ever been detected?
However, what we now assume and may use in a modern derivation for the Blackbody spectrum does NOT change what Planck originally assumed and how he started to explain the spectrum.
Something like this.
I wonder how can anyone disagree with this.
but not every em spectrum is necessarily quantised.
Why does a hydrogen atom have quantised energy?
Quote from: Bored chemist on 12/06/2023 17:29:29Why does a hydrogen atom have quantised energy?It's all down to Heisenberg and Schrodinger.
Quote from: alancalverd on 12/06/2023 22:54:27Quote from: Bored chemist on 12/06/2023 17:29:29Why does a hydrogen atom have quantised energy?It's all down to Heisenberg and Schrodinger.No.Grass was green before either of them was born.
I thought it was something to do with the molecular orbitals
And we model the molecular orbitals as combinations of atomic orbitals.
So we all look forward to your explanation without using anything that Heisenberg, Schrodinger or Pauli wrote
Whatever happened to delocalisation since 1963?
I found at least one statement that was made which isn't necessarily true. In the second video at about 7:00 to 7:30 the narrator discusses the use of a cuboidal shaped cavity for the mathematical model (which is the typical choice). There is a fairly casual statement made that any shaped cavity could have been used, the result would be the same but the maths would just be harder. That is not at all obvious and I don't think it should be stated as established fact.
Incidentally, hot hydrogen atoms do have a strong absorption for red light.It's the hydrogen alpha line looked at from the other point of view.