If the transition is instantaneous, the moment the photon appears must be superluminal.
In quantum mechanics, Bohr's semi-classical model, Heisenberg's matrix mechanics, and Schödinger's wave function are all able to support the assumption of energy levels of atoms and coincide with the spectra of atoms. It is the operating mode of most light sources, including lasers. This shows that the body of their theories is all correct. If they are merged into one theory describing the structure image, it must have the characteristics of all three at the same time. Bohr's ∨ Heisenberg's ∨ Schödinger's, will form the final atomic theory*.
The jump of an electron in an atom, whether absorbed or radiated, is in the form of a single photon, and taking the smallest energy unit. For the same energy difference ΔE, jumping chooses a single photon over multiple photons with lower frequency ν, suggesting that a single photon structure has a more reasonable match between atomic orbital structures**.
ΔE=hν ......(1)
ΔE=Em-En ......(2)
It is clear that without information about Em, En at the same time, generating a definite jump frequency ν is impossible. "Rutherford pointed out that Rutherford pointed out that if, as Bohr did, one postulates that the frequency of light ν, which an electron emits in a transition, depends on the difference between the initial energy level and the final energy level, it appears as if the electron must "know" the frequency of light ν. level and the final energy level, it appears as if the electron must "know" to what final energy level it is heading in order to emit light with the right frequency."[1].
Bohr's postulate of Eq. (1)(2) energy level difference is valid [2]. But it does not hold as axiomatic postulate. This is not just because all possible reasons have not been ruled out. For example, one of the most important reasons is that the relationship between the "wave structure" of the electron and the electromagnetic field has not been determined†. Only if this direct relationship is established can the transition process between them be described. It is also required that the wave function and the electromagnetic field are not independent things, and it is required that the wave function is a continuous field distribution, not a probability distribution [5]. More importantly, Eqs. (1)(2) do not fulfill the axiomatic condition of being axiomatic postulate, which is not capable of ignoring the null information‡.
Doing it as a comparison of questions is the same as when we ask how the photon controls its speed [3] and where the photon should reach next. They are both photon behaviors that must rest on a common ground.
Considering the electron transition as a source of light, it is equally consistent with the principle of Special Relativity, and the photons radiated must be at the speed of light c and independent of the speed of the electrons††. However, if the light-emitting process is not continuous, the phenomenon of superluminal speed occurs.
We decompose the light-emitting process into two stages. The first stage, from "nothing" to "something", is the transition stage; the second stage, from something to propagation, is the normal state. According to classical physics, if the light emission is instantaneous, i.e., it does not occupy time and space. Then we can infer that the photon from nothing to something is not a continuous process, but an infinite process, and the speed at which the photon is produced is infinity. We cannot believe that the speed of propagation of light is finite and the speed at which light is produced is infinite. There is no way to bridge from the infinite to the finite, and we believe that this also violates the principle of the constancy of the speed of light.
There is no other choice for the way to solve this problem. The first is to recognize that all light emitting is a transitional "process" that occupies the same time and space, and that this transitional process must also be at the speed of light, regardless of the speed of the source of light (and we consider all forms of light emitting to be sources of light). This is guaranteed by and only by the theory of relativity. SR will match the spacetime measure to the speed of light at any light source speed. Secondly, photons cannot occur in a probabilistic manner, since probability implies independence from spacetime and remains an infinity problem. Third, photons cannot be treated as point particles in this scenario. That is, the photon must be spatially scaled, otherwise the transition process cannot be established. Fourth, in order to establish a continuous process of light emission, the "source" of photons, whether it is an accelerated electron, or the "wave function" of the electron jump, or the positive and negative electron annihilation, are required to be able to, with the help of space and time, continuous transition to photons. This will force us to think about what the wave function is.
Thinking carefully about this question, maybe we can get a sense of the nature of everything, of the extensive and indispensable role of time and space.
Our questions are:
1) Regardless of the solution belonging to which theory, where did the electron get the information about the jump target? Does this mean that the wave function of the electron should span all "orbitals" of the atom at the same time.
2) If the jump is a non-time-consuming process, should it be considered a superluminal phenomenon¶ [4]?
3) If the jump is a non-time consuming process, does it conflict with the Uncertainty Principle [5]?
4) What relationship should the wave function have to the photon to ensure that it produces the right photon?
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Notes:
* Even the theory of the atomic nucleus. After all, when the nucleus is considered as a "black box", it presents only electromagnetic and gravitational fields.
* * It also limits the possibility that the photon is a mixed-wavelength structure. "Bohr noticed that a wave packet of limited extension in space and time can only be built up by the superposition of a number of elementary waves with a large range of wave numbers and frequencies [2].
† For example, there is a direct relationship between the "electron cloud" expressed by the wave function of the hydrogen steady state, and the radiating photons. With this direct relationship, it is possible to determine the frequency information between the transition energy levels.
‡ If a theory considers information as the most fundamental constituent, then it has to be able to answer the questions involved here.
†† Why and how to achieve independence from the speed of light cannot be divorced from SR by its very nature, but additional definitions are needed. See separate topic.
¶ These questions would relate to the questions posed in [3][4][5].
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References:
[1] Faye, J. (2019). "Copenhagen Interpretation of Quantum Mechanics." The Stanford Encyclopedia of Philosophy from .
[2] Bohr, N., H. A. Kramers and J. C. Slater (1924). "LXXVI. The quantum theory of radiation." The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 47(281): 785-802. This was an important paper known as "BSK"; the principle of conservation of energy-momentum was abandoned, and only conservation of energy-momentum in the statistical sense was recognized.
[3] “How does light know its speed?”;
https://www.researchgate.net/post/NO3_How_does_light_know_its_speed;
[4] “Should all light-emitting processes be described by the same equations?”;
https://www.researchgate.net/post/NO11_Should_all_light-emitting_processes_be_described_by_the_same_equations;
[5] “Does Born's statistical interpretation of the wave function conflict with ‘the Uncertainty Principle’?” https://www.researchgate.net/post/NO13_Does_Borns_statistical_interpretation_of_the_wave_function_conflict_with_the_Uncertainty_Principle;