3.2. Detailed Derivation of the Revised Radiation Energy Density Formula
Based on the revised classical electrodynamics theory [
3,
4], the physical essence of radiation within a blackbody cavity is the transition radiation of numerous "electron-nucleus bound systems" excited thermally at different frequencies. The specific derivation process is as follows:
Step 1: General Expression for Electron Transition Power
According to revised classical electrodynamics [
3], when an electron accelerates and completes one revolution around the nucleus, it radiates an amount of energy
ε. Therefore, within a time interval Δ
t, if
k units of energy ε are radiated, the total radiated energy is ΔE
= kε, and the radiation power can be expressed as:
The frequency
ν of this radiation satisfies
ν=
k/Δ
t. The radiation power can thus be expressed as a function of frequency
ν:
This equation indicates that the radiation power P is directly proportional to the radiation frequency ν, with the proportionality constant being ε.
Step 2: Statistical Weight of Radiation Processes at Different Frequencies under Thermal Equilibrium
In a blackbody cavity at thermal equilibrium, there exists a vast number of microscopic systems capable of radiating. To sustain a radiation process of frequency ν, the energy that must be transferred within a time Δt is:
To simplify subsequent calculations, we take the unit observation time Δt=1s. Then, εΔt=h, ν=k/Δt=k and ΔE==hν. That is, the total energy required to generate a radiation process of frequency ν is ΔE == hν.
In a thermal equilibrium state, there exists competition among radiation processes of different frequencies within the system: radiation processes with higher energy require overcoming higher thermal energy barriers and thus have lower probabilities of being thermally excited. This probability follows the Boltzmann distribution, whose core physical meaning is that "in a thermal equilibrium system, the occupation probability of a physical state is exponentially related to the energy of that state", with the specific form given by:
Here, k is the energy count number (corresponding to the radiation frequency ν = k), and Prob (k) represents the "probability weight for the radiation process with frequency ν = k to be excited under thermal equilibrium". The larger k is (indicating higher frequency and higher energy), the smaller the probability weight, which fully aligns with the physical intuition of thermal statistics.
Note on Discrete Summation and Continuous Frequency
Physically, the radiation frequency ν is a continuous variable. In the following statistical summation, we discretize the continuous frequency ν into a sequence νk=k/Δt, where k= 0, 1, 2, ..., and take the unit observation time Δt = 1 s. This treatment is based on two points:
(1)The numerical value of the minimum energy unit ε is extremely small (ε = h≈ 6.626×10-34 J), making the error introduced by the frequency resolution ν = 1 Hz negligible in macroscopic statistics.
(2)Using discrete summation allows for a clearer presentation of the physical picture where energy transfer is measured in units of ε, and facilitates subsequent asymptotic analysis. In situations requiring strict continuous treatment, the summation can be replaced by an integral over ν, with the energy term in the integrand being E = hν.
Step 3: Calculation of Average Radiation Power
Considering all possible radiation processes at frequencies ν (
corresponding to all positive integers k), the average radiation power of the system when in the corresponding state can be calculated via statistical summation:
where
v=εk
(numerically equal).
Step 4:Asymptotic Behavior Analysis (Low and High Frequency Limits)
For ease of analysis, let x=kε/kBT=/kBT.
Low-frequency region (
x ≪ 1): Here,
kε ≪
kBT, meaning the energy of the radiation process is much smaller than the thermal energy. Consequently, radiation processes of all frequencies can be sufficiently excited, and the probability weight exp(-
kε/(
kBT)) ≈ 1. The summation can be approximated as a continuous integral, ultimately yielding the classical statistical average power:
This is consistent with the low-frequency behavior of the Rayleigh-Jeans formula, reflecting the applicability of classical statistics.
High-frequency region (
x ≫ 1): Here,
kε ≫
kBT, meaning the energy of the radiation process is much greater than the thermal energy. Only radiation processes near
k≈
k0=k
BT/
ε (the characteristic count number corresponding to thermal energy) have a non-negligible excitation probability. Processes far from
k0 (
k>
k0) contribute negligibly due to the exponential decay of the probability weight exp (-
kε/(
kBT)). Consequently, the average power exhibits exponential decay:
This behavior directly suppresses the energy divergence in the high-frequency region, thereby successfully eliminating the ultraviolet catastrophe.
Step 5: Unified Expression and Energy Density Formula
Integrating the above limiting behaviors, the average power can be expressed piecewise as:
Classical electromagnetic theory gives the mode density per unit volume per unit frequency interval as:
. Substituting the average power yields the revised radiation energy density formula:
This formula is consistent with the Rayleigh-Jeans formula in the low-frequency region, naturally exhibits exponential decay in the high-frequency region, thereby successfully eliminating the ultraviolet catastrophe, and is in complete agreement with experimental observations.
3.3. Detailed Derivation and Physical Meaning of High-Frequency Asymptotic Behavior
Step 1: Specific Expression in the High-Frequency Region
When
, from Eq. (3.7) we obtain:
Step 2: Define Temperature-Dependent Constant
Then Eq. (3.8) can be written as:
Step 3: Limiting Behavior Analysis
As ν→∞, the exponential term
decays much faster than the polynomial term
grows, therefore:
Step 4: Explanation of Physical Mechanism
The physical root cause of the exponential decay in the high-frequency region lies in:
Thermal Power Threshold Effect: When , the energy ΔE = hν required to generate radiation at this frequency is much greater than the thermal energy kBT, causing its thermal excitation probability ∝exp(−hν/kBT) to decay exponentially.
Energy-Time Constraint Mechanism: The minimum time to complete one electromagnetic oscillation is Δtmin=1/ν, and the minimum energy transfer unit is ε. Therefore, the theoretical maximum power is:
Even given this power upper limit, the actual average power is still suppressed by the thermal excitation probability, manifesting as .
Step 5: Elimination of the Ultraviolet Catastrophe
The classical Rayleigh-Jeans formula assumes all modes equally share energy kBT, i.e., , leading to divergence of the high-frequency integral.
In the revised model, in the high-frequency region
, where exponential decay dominates, ensuring:
The ultraviolet catastrophe is naturally eliminated.
3.4. Unified Explanation of Blackbody Radiation Phenomena by the Revised Model
The revised formula (3.7) naturally reduces to the Rayleigh-Jeans form in the low-frequency region (hν≪kBT), consistent with low-frequency experimental data. In the high-frequency region (hν≫kBT), it exhibits exponential decay, successfully eliminating the ultraviolet catastrophe. More importantly, this formula originates from a self-consistent classical physics framework and provides a unified explanation for the complete phenomenology of blackbody radiation without introducing any non-classical assumptions.
Starting from the revised formula, the empirical Wien's displacement law and the Stefan-Boltzmann law can be further derived. The physical mechanism of Wien's displacement law (the peak frequency νmax is proportional to temperature T) is clear and intuitive in this model: it stems from the competitive balance between the radiated power P=εν and the thermal energy kBT. When the temperature T increases, the thermal excitation energy strengthens, enabling the support of higher-frequency (higher-power) radiation processes, which shifts the spectral peak toward higher frequencies. The Stefan-Boltzmann law (the total radiant exitance M(T)∝T4) is a natural outcome derived first by integrating the energy density spectrum to obtain the total energy density , and then applying the classical radiation propagation relation M(T)=U(T) . Since the dimensional chain of all physical quantities in this model—the mode density , the average power , and the energy density u(ν,T)—is strictly self-consistent, this integration has a clear physical meaning. The resulting T4 law is an inevitable manifestation of continuous energy transfer modulated by thermal statistics.
3.5. Fundamental Differences from Planck's Approach: A Comprehensive Analysis from Formula to Laws
The standard form of Planck's blackbody radiation formula is:
Although Planck's blackbody radiation formula (3.11) can mathematically fit experimental data and derive the same empirical laws, its entire theoretical system—from basic assumptions to law derivation—exhibits a series of fundamental differences from the revised model presented in this paper, revealing deep-seated defects in its physical self-consistency.
3.5.1. Fundamental Differences in Physical Construction Pathways and Core Parameters
Although mathematically similar in the high-frequency region, the revised model and Planck's formula exhibit a series of irreconcilable, principled differences in their physical construction pathways, core parameters, and basic assumptions, analyzed in detail below.
(1) Drastically Different Physical Pictures and Radiation Mechanisms
The revised model, based on revised classical electrodynamics, presents a physical picture where numerous "electron-nucleus bound systems" within the blackbody cavity undergo thermal excitation, causing electrons to perform variable-speed (accelerating/decelerating) spiral motion. The continuous change in the electron's motion frequency leads to continuous energy radiation. Radiation is directly and continuously linked to changes in the electron's motion state. In contrast, the Planck model assumes the blackbody cavity walls consist of many independent "harmonic oscillators". Radiation originates from transitions between discrete energy levels of these oscillators, with energy exchange occurring instantaneously in integer multiples of the energy quantum hν, a process that is inherently non-continuous.
(2) Opposing Physical Natures of Core Parameters
In the revised model, the key introduced parameter ε is a minimum energy unit of measurement. Its numerical value equals the Planck constant h, but its physical essence is a unit of energy (J). Its role is analogous to "liters" or "seconds", used to measure the magnitude of a continuous energy flow, without altering the intrinsic continuity of the energy transfer process. In Planck's theory, the Planck constant h is the quantum of action, having the dimension of action (J·s). Its product with frequency, hν, is endowed with a new physical meaning – an indivisible discrete energy packet – implying that energy itself is assumed to be a granular physical entity.
(3) Fundamental Disagreement on the Physical Meaning of Key Variables (k vs. n)
This distinction lies at the core of the divergence between the two theories. In the derivation of the revised model, the key variable k is a positive integer with a clear physical meaning: it represents the number of energy measurement units ε transferred in a radiation process of frequency ν within a unit observation time (Δt = 1 s), satisfying the relation ν = k. Therefore, k is an indicator describing the "intensity of the radiation process", and it corresponds one-to-one with the radiation frequency. In Planck's derivation, the key variable n is the "quantum number", indicating that the oscillator's energy is an integer multiple of its ground state energy hν, i.e., En = n hν. n is a quantum number identifying the "energy level state of the oscillator". The former (k) describes the measurement outcome of a dynamic process, while the latter (n) describes the discrete state of a static system.
(4) Essentially Opposed Origins of "Quantization"
This directly leads to completely different explanations for the origin of "quantization" phenomena. In the revised model, the appearance of energy in "packets" stems from the discreteness of measurement and process: Energy transfer is continuous, but because changes in electron frequency occur in units (Hz) as the minimum increment, statistically, energy accumulation and release naturally appear discrete based on the minimum measurement unit ε. This is akin to measuring a continuous water flow with a fixed-capacity bucket; the continuity of the flow remains unchanged. Conversely, Planck's theory attributes "quantization" to the discreteness of energy itself, positing that energy is physically indivisible and infinite, with its fundamental unit being hν. This constitutes a complete overturning of the classical concept of energy continuity.
(5) Differences in Statistical Objects and Derivation Goals
Consequently, the objects over which the two theories perform mathematical summation (or integration) are also different. The revised model performs statistics on all possible radiation processes at different frequencies ν (i.e., all possible k values), aiming to calculate the average power ⟨P⟩ of these processes under thermal equilibrium. The Planck model, however, performs statistics on all possible discrete energy levels n of harmonic oscillators at the same fixed frequency ν, aiming to calculate that oscillator's average energy . The former directly handles the frequency spectrum, while the latter first handles the single-frequency energy distribution before extrapolating to the spectrum.
(6) Compatibility with the Classical Physics Framework
The ultimate manifestation of all the above differences is the fundamentally different relationship each theory has with classical physics. The entire construction of the revised model is completed within the classical physics framework (revised electrodynamics, Newtonian mechanics, continuous energy view, classical statistics) and is fully compatible with classical physics. It demonstrates that so-called "quantization" phenomena are statistical manifestations of classical laws under specific constraints. Planck's energy quantization hypothesis, from its inception, was fundamentally in conflict with classical physics. It forcibly broke the classical understanding of continuous energy change, thereby ushering in the era of quantum theory, which diverged from classical physics.
To clearly summarize these fundamental differences, a comparison table is provided below (
Table 2):
The construction pathway of the revised model can be clearly described as based on statistics of classical continuous energy transfer:
When measured per unit time (1 s), ν =
k, the radiation energy density formula can be written as:
Here, ε appears as an energy unit of measurement, used to measure the energy flow in the continuous radiation process.
3.5.2. Fundamental Differences in Theoretical Structural Self-Consistency: Physical Applicability of Mode Density
The construction logic of the revised model is internally self-consistent. Its core physical picture is that radiation processes at various frequencies ν are directly generated within the blackbody cavity. The mode density formula here describes the distribution weight of radiation processes at different frequencies, and its physical meaning (frequency distribution) perfectly matches the statistical object (processes at different frequencies). Therefore, the energy density formula is seamlessly connected in theoretical structure.
The construction of Planck's formula, however, exhibits a significant logical discontinuity. Its core step is calculating the average energy of a harmonic oscillator at a fixed frequency ν, which belongs to statistics of "different energy states at the same frequency". Yet, he subsequently multiplies this average energy directly by the classical formula , which describes the distribution of electromagnetic modes at different frequencies, to obtain the total energy density . This essentially forcibly "grafts" two physical quantities with drastically different physical premises: stems from the quantum hypothesis of "single-frequency energy level distribution", while stems from the classical electromagnetic theory of "multi-frequency mode distribution". Although this grafting mathematically yields a result matching experiments, there is an inherent inconsistency in the connection of physical concepts. This defect further indicates that Planck's formula resembles more of a "hybrid model" constructed to fit data, rather than an inevitable result derived from a unified, self-consistent first-principles physics.
3.5.3. Re-Examining Theoretical Foundations from Empirical Laws: Analysis of the Derivations of Wien's Displacement Law and the Stefan-Boltzmann Law
The derivations of Wien's displacement law and the Stefan-Boltzmann law further highlight the relative strengths and weaknesses of the two theories at their foundations.
Difference in the Physical Interpretation of Wien's Displacement Law:
In Planck's theory, this law is interpreted as follows: an increase in temperature makes it easier for harmonic oscillators to occupy higher energy levels (increasing n), and higher energy levels correspond to larger energy quanta hν, thus shifting the radiation peak toward higher frequencies. This interpretation entirely depends on the core assumption that "the same frequency ν corresponds to multiple discrete energy levels n hν". However, as discussed earlier, this assumption contradicts the fundamental physical fact revealed by our model—that "frequency ν uniquely determines the radiated power P = ε ν". It lacks support from microscopic motion mechanisms and appears more like a mathematical construct introduced to explain the phenomenon.
In the revised model, the physical interpretation of this law is direct and natural: the peak position is determined by the balance between energy supply and demand. High-frequency radiation requires higher power (P = ε ν), and only sufficiently high temperature (thermal energy kBT) can effectively excite it. The physical picture is clear and requires no additional assumptions.
Dimensional and Logical Pitfalls in the Derivation of the Stefan-Boltzmann Law:
Planck's theory requires integrating over the entire frequency domain. However, since the core component of , , has the dimension of momentum density (energy flux density) [ML−1T−1], the physical meaning of the integral ∫u(ν,T)dν is essentially ambiguous—it sums terms that are dimensionally inconsistent. Although mathematically, using the known integral yields a neat T⁴law, the appearance of the π4 factor in the constant σ within this framework is merely a mathematical coincidence lacking direct physical explanation.
In the revised model, since the dimensional self-consistency of is maintained throughout ([L−3T]⋅[ML2T−3]=[ML−1T−2]), the integration of this expression has a clear physical meaning: "summing the radiated energy of all frequencies per unit volume". The resulting T⁴law and its constant are natural products of the combination of classical mode distribution and the thermal statistics of continuous energy transfer. The entire derivation chain is logically rigorous and its physical interpretation is clear.
Conclusive Comparison: Planck's approach, by introducing the non-classical hypothesis of "energy discretization" and relying on mathematical constructs with dimensional and conceptual leaps, "calculates" the correct blackbody radiation formula and its corollaries, but its theoretical foundation contains inherent contradictions that cannot be reconciled. In contrast, the revised model presented in this paper demonstrates that, without breaking the continuity and self-consistency of classical physics, it is sufficient to self-consistently derive all laws of blackbody radiation—including the elimination of the ultraviolet catastrophe, Wien's displacement law, and the Stefan-Boltzmann law—merely by clarifying the electron motion-radiation mechanism and adopting dimensionally strict, logically consistent statistical methods. This not only fulfills Planck's unfulfilled wish for a classical explanation but also offers a new and more solid understanding of the essence of the "quantization" concept and its relationship with classical physics.