Forbidden Transitions Indicates That Low-Energy Light Is Not a Particle — A Reinterpretation of Light Based on Natural Quantum Theory

Lei Yian

I. Introduction: An Overlooked Fact

In the standard narratives of quantum mechanics and quantum electrodynamics (QED), light is regarded as discrete particles — photons.Every atomic transition is described as "emitting one photon";every absorption as "absorbing one photon."

However, a large number of so-called "forbidden transitions" exist in nature —transitions labeled in quantum selection rules as "having extremely low or even zero probability."Yet they do occur and are clearly observed in extremely rarefied spaces (such as interstellar media and plasma halos).

This is a profound yet overlooked clue:

If light were truly particles, these "forbidden transitions" should not exist at all.

II. What Are Forbidden Transitions?

Taking hydrogen atoms and hydrogen-like ions as examples, common transitions follow the following dipole moment selection rules:

Δl = ±1, Δm = 0, ±1

In other words, photons (as spin-1 particles) can only carry one unit of angular momentum.Therefore, transitions such as 2s→1s are regarded as "forbidden,"as they require the emission of two photons to conserve angular momentum.

Nevertheless, astrophysical observations have long confirmed:

In rarefied ionized hydrogen gas, the radiation from 2s→1s transitions does exist;

with a lifetime as long as approximately 0.12 seconds, it can stably emit light.

Such radiation has been widely verified in fields such as nebular spectral lines, plasma radiation, and laser cooling.In other words, the so-called "forbidden" is merely a man-made definition —nature does not prohibit it.

III. The Logical Dilemma of the Photon Theory

Under the photon model, the following must hold:

A single photon carries ℏ of angular momentum;

Each transition must conserve energy and angular momentum;

The quantum numbers of the initial and final states of the atom determine whether "one photon can be emitted."

This gives rise to a logical problem:

If only one photon can be emitted, but the transition requires the conservation of two units of angular momentum, it is impossible;

If two-photon simultaneous emission is allowed, it means a single transition needs to emit two "particles" at the same time;

Yet photons have no mutual interaction in a vacuum — how can they be generated simultaneously, synchronously, and share energy?

This forces QED to adopt an extremely complex second-order perturbation theory to "allow" such transitions —i.e., through virtual particle mediation, vacuum fluctuations, and Feynman diagram corrections, making the transition "non-zero probability."

However, the essence of this explanation is piling patches on a wrong model.Physically, the fundamental problem lies in:

If light is an indivisible particle, the occurrence of any "forbidden transition" is a counterproof to the particle model.

IV. The Perspective of Natural Quantum Theory: Light Is a Continuous Field, and Emission Is a Relaxation Process

Natural Quantum Theory (NQT) redefines light and radiation:

Light is a continuous electromagnetic field, not a stream of discrete particles;

A "transition" is not an instantaneous jump, but a relaxation process in which the field structure of a charged system transitions from one steady-state vibration mode to another;

The release of radiant energy is a continuous fluctuating energy redistribution, not a particle emission event.

In this picture:

The so-called "forbidden transitions" are merely slow relaxations that can still occur through higher-order field modes (such as quadrupole and magnetic dipole) when the dipole moment term is approximated to zero;

The light field is no longer confined to carrying "one unit of angular momentum," as the real rotation modes of the electromagnetic field have a continuous angular momentum distribution;

Therefore, there is no "forbidden," only low radiation efficiency.

This is fully consistent with astronomical observations:Rarefied plasmas in the universe can maintain excited states for a long time and release energy through these slow field modes.

V. Low-Energy Light: The Limit of Waves, Not Particles

The light emitted by forbidden transitions is usually extremely low in energy and very long in wavelength.This precisely indicates:

Light behaves more like a continuous wave than a particle in the low-energy region.

If light were particles, low energy would mean low-frequency sparse emission,and particles should be independent of each other without coherent superposition.But the actual situation is the opposite:These low-energy radiations exhibit high coherence in space, long-term persistence, and full consistency with the electromagnetic wave equation.

Experimentally, all "single-photon experiments" in the low-energy region cannot verify the independent existence of photons;on the contrary, interference fringes still exist when the light intensity is extremely weak.

This shows:

The essence of light is the continuous fluctuation of the field;

The so-called "particle nature of photons" is only a discrete mapping of emission events;

Light itself is not discrete.

VI. The Philosophical Significance of Forbidden Transitions: Nature Does Not Need "Mysterious Particles"

The fact revealed by "forbidden transitions" is extremely profound:Nature has never truly "quantized" light.

The so-called "quantization" is only a reflection of the spectral structure in discrete energy level systems.

The nature of the light field is continuous,and the discreteness of energy comes from the modal structure of the emitter.

This means:

The "photon" is not a fundamental particle, but a discrete count of the energy units of the field under an artificial measurement framework;

The radiation behavior in the low-energy light region cannot be explained by the "single-particle" picture, but fully conforms to the relaxation dynamics of continuous waves;

The existence of "forbidden transitions" is an experimental self-negation of the photon theory.

VII. Conclusion: The End of Particles, the Return of Fields

The century-old "photon belief" has promoted technological revolutions,but in terms of understanding, it has also created artificial confusion:"Forbidden transitions cannot occur, yet they do";"Photons are discrete, yet they can interfere";"The vacuum has no energy, yet it can be polarized."

The ultimate cause of these contradictionsis that we mistake the mathematical structure of the frequency spectrum for physical reality,and the discreteness of emission events for the discreteness of the field itself.

Natural Quantum Theory tells us:

Light is not a particle,but nature’s field;

Radiation is not an instantaneous jump,but a continuous flow of energy.

Forbidden transitions existbecause nature has never prohibited the relaxation and release of energy —what is prohibited is only our narrow interpretation.

Nature is not quantized; it is merely continuous, elegant, and misunderstood.