Thermal radiation

Question

I've read previous answers to this question and still feel it's not answered. Wikipedia, in the first paragraph of its article on thermal radiation, states its origin is from oscillating electric dipoles, and/or accelerating or decelerating charges. Applying this to a monoatomic non-ionized material, does the mechanism of oscillation/acceleration occur independently of electronic transitions between orbital levels in an atom? This goes to the discrete/continuous spectrum question.

Answer 1

Oscillation and acceleration of charges is a pre-quantum-theoretical concept that is part of explanation of any EM radiation, not just the thermal one.

This mechanism is not really considered too often in the standard quantum theory of radiation, where the electronic transitions are often talked about.

In this theory all is very mathematical, focused on psi functions rather than on what the particles are really doing and the theory is devoid of clear 3D model of what is happening. One cannot easily trace and observe electrons in the calculation to be oscillating and accelerating. The changes in atoms/molecules should be continuous due to Schroedinger's equation, but are almost always conceptually simplified into discrete level transitions.

But oscillations and accelerated motion of charges are, in a way, displayed in the solutions of the Schroedinger's equation for some situations like when atom/molecule interacts with external laser light. In the simplified language the atom/molecule undergoes 'electronic transitions', but such changes can be mathematically described by oscillating psi functions that change in time from one eigenfunction to another eigenfunction.

So oscillation/acceleration of charges is an idea that is coming from a different direction than electronic transitions, but at the level of Schr. equation, it actually can be identified with oscillating solutions of the Schr. equation. Most often this is too much work and people use simplified terminology and calculation scheme - the golden rule - to treat the processes as discrete transitions.