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Wave Pendulum and Prime Numbers: A Spectral Isomorphism via Riemann Zeta Zeros

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30 January 2026

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03 February 2026

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Abstract
This paper explores a spectral isomorphism between wave pendulum dynamics and prime number patterns via Riemann zeta zeros. We demonstrate that both systems share mathematical structures based on superposition of discrete frequency components, leading to comparable interference phenomena. The temporal evolution of the wave pendulum relates to logarithmic scaling in prime distributions, with both patterns emerging from similar spectral principles mediated by Riemann zero contributions. Analytical derivation and numerical analysis support this correspondence, suggesting connections between mechanical systems and number-theoretical concepts through spectral geometry.
Keywords: 
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1. Introduction

1.1. Historical Context

The visual representation of mathematical structures has long provided insights into abstract concepts. The wave pendulum (or harmonic pendulum array) has fascinated physicists and mathematicians since its invention, displaying complex patterns from simple harmonic motions [10,13]. Simultaneously, the study of prime number distributions through geometric visualizations has revealed unexpected patterns that hint at deeper mathematical structures, beginning with Ulam’s discovery of diagonal patterns in his spiral arrangement of integers [12] and later refined in the Sacks spiral [8].

1.2. The Fundamental Connection

Recent work by Souto (2026) [9] demonstrates that prime number spirals are interference patterns generated by Riemann zeta zeros. Independently, the wave pendulum exhibits visually similar patterns through the superposition of harmonically related oscillations. This paper establishes that these similarities are not coincidental but stem from identical mathematical foundations.

2. Mathematical Foundations

2.1. The Wave Pendulum System

Consider N simple pendulums with lengths L n arranged in decreasing order. For small oscillations, each pendulum follows the equation:
θ n ( t ) = A n cos ( ω n t + ϕ n )
where the angular frequency is given by:
ω n = 2 π f n = g L n
The classic wave pendulum configuration uses harmonically related lengths:
L n = L 1 n 2 , n = 1 , 2 , 3 , , N
which gives frequencies:
ω n = n ω 1 , where ω 1 = g L 1
The instantaneous spatial pattern formed by the pendulum array at time t is:
Θ ( n , t ) = A n cos ( n ω 1 t + ϕ n ) , n = 1 , 2 , , N

2.2. Spectral Analysis of the Wave Pattern

The spatial pattern can be analyzed through discrete Fourier transform. Consider the complex representation:
Z ( n , t ) = A n e i ( n ω 1 t + ϕ n )
The collective pattern across all pendulums at fixed t is:
P ( t ) = n = 1 N Z ( n , t ) = n = 1 N A n e i ϕ n e i n ω 1 t
This represents a discrete inverse Fourier transform where n ω 1 are the frequency components and t serves as the transform variable.
Theorem 1 
(Pendulum Fourier Decomposition). The wave pendulum pattern P ( t ) is the inverse discrete Fourier transform of the complex amplitude vector A n e i ϕ n evaluated at frequency ω = n ω 1 t .
Proof. 
Starting from equation (7):
P ( t ) = n = 1 N A n e i ϕ n e i n ω 1 t = n = 1 N c n e i ω n t with ω n = n ω 1 , c n = A n e i ϕ n
This matches the definition of inverse discrete Fourier transform. □

2.3. Interference Conditions

Constructive interference occurs when multiple pendulums align in phase. For two pendulums m and n:
n ω 1 t + ϕ n m ω 1 t + ϕ m ( mod 2 π )
( m n ) ω 1 t ϕ n ϕ m ( mod 2 π )
This defines specific times when particular spatial patterns emerge, creating the characteristic "wave" effects.

2.4. Prime Numbers and Riemann Zeta Function

The Riemann zeta function is defined for ( s ) > 1 by:
ζ ( s ) = n = 1 1 n s = p P ( 1 p s ) 1
The non-trivial zeros ρ = 1 2 + i γ n satisfy ζ ( ρ ) = 0 . The connection between primes and zeta zeros originates from Riemann’s seminal work [7]. Extensive computational verification of these zeros has been conducted, including up to the 10 22 nd zero [5]. The Riemann-von Mangoldt explicit formula [11] relates primes to these zeros:
ψ ( x ) = x ρ x ρ ρ ζ ( 0 ) ζ ( 0 ) 1 2 log ( 1 x 2 )
where ψ ( x ) is the Chebyshev function.

2.5. Sacks Spiral Coordinates

In the Sacks spiral, integers n are plotted in polar coordinates:
r ( n ) = n
θ ( n ) = 2 π n φ 2
where φ = ( 1 + 5 ) / 2 is the golden ratio.
For prime numbers p, only points ( r ( p ) , θ ( p ) ) are plotted, revealing spiral arms.

2.6. Spectral Interpretation of Prime Spirals

Following Souto (2026) [9], each zeta zero contributes to prime positions. The regularity observed in prime number distributions has been studied from various perspectives [3], but the spectral interpretation provides a new geometric framework:
W ρ ( p ) = p ρ ρ = p ρ e i γ ln p
The total influence is the superposition:
S ( p ) = ρ W ρ ( p ) = p ρ e i γ ln p ρ
Prime clustering occurs when the phases align constructively, i.e., when:
γ m ln p γ n ln p ( mod 2 π )
for multiple zeros γ m , γ n .

3. The Mathematical Isomorphism

3.1. Mapping Between Systems

Table 1. Mathematical correspondence between systems.
Table 1. Mathematical correspondence between systems.
Wave Pendulum Prime Spirals Correspondence
Pendulum index n ln p (log prime) Independent variable
Time t Zero γ k Frequency parameter
Phase n ω 1 t Phase γ k ln p Linear phase accumulation
A n e i n ω 1 t p ρ e i γ ln p Complex contribution
n A n e i n ω 1 t ρ p ρ e i γ ln p Superposition principle
( m n ) ω 1 t = 2 π k ( γ m γ n ) ln p = 2 π k Interference condition

3.2. Rigorous Derivation of Isomorphism

3.2.1. From Pendulum to Zeta Zeros

Consider the wave pendulum’s spatial pattern as a function of normalized position x = n / N :
Ψ ( x , t ) = n = 1 N A ( x ) e i n ω 1 t
In the continuum limit N , this becomes:
Ψ ( x , t ) = 0 1 A ( ξ ) e i ξ ω max t d ξ
where ω max = N ω 1 .
Now consider the prime distribution as a sum over zeta zeros. The explicit formula can be written as:
Δ ( p ) = γ e i γ ln p 1 2 + i γ
Define the change of variables:
ξ = γ γ max , τ = ln p
Then:
Δ ( τ ) = 0 1 e i ξ γ max τ 1 2 + i ξ γ max d ξ
Comparing Equations (18) and (21), we see they have identical mathematical structure:
Ψ ( x , t ) Pendulum Δ ( τ ) Primes with ω max t Pendulum γ max τ Primes

3.2.2. Interference Pattern Equivalence

The interference condition for the pendulum (from Equation 8):
t m n ( k ) = 2 π k + ( ϕ n ϕ m ) ( m n ) ω 1
For primes (from Equation 16):
ln p m n ( k ) = 2 π k γ m γ n
These are formally identical with the mapping:
t ln p , ( m n ) ω 1 ( γ m γ n )
Theorem 2 
(Interference Isomorphism). The interference conditions for wave pendulum and prime number distribution are mathematically isomorphic under the mapping t ln p and ω n γ n .
Proof. 
Starting from pendulum interference:
( m n ) ω 1 t = 2 π k t = 2 π k ( m n ) ω 1
For prime interference:
( γ m γ n ) ln p = 2 π k ln p = 2 π k γ m γ n
With mapping ω n γ n and t ln p , the equations are identical. □

3.3. Spectral Density Comparison

The spectral density of frequencies in both systems follows similar distributions:
For the wave pendulum with L n = L 1 / n 2 :
ω n = n ω 1 d n d ω = 1 ω 1 ( uniform density )
For Riemann zeta zeros, the asymptotic density derived from analytic number theory [11] is:
N ( T ) = T 2 π log T 2 π T 2 π + O ( log T )
giving:
d N d γ 1 2 π log γ 2 π
Lemma 1 
(Spectral Density Similarity). Both systems have slowly varying spectral densities, leading to similar interference phenomena despite different functional forms.

4. Extended Theory: The Role of Parameter k as Interference Harmonics

4.1. Parameter k: Quantization of Interference

The parameter k in the arm angle formula represents the interference harmonics, analogous to harmonics in oscillating physical systems. The fundamental condition for constructive interference is:
γ m ln ( p ) γ n ln ( p ) + 2 π k ( mod 2 π )
where k Z + is the quantization number, leading to:
Θ m n ( k ) = 2 π k · γ m γ m γ n mod 2 π

4.2. Physical Interpretation of k as Harmonics

4.2.1. Analogy with Standing Waves

Consider two waves with frequencies ω m and ω n :
  • Fundamental beat frequency: | ω m ω n | (corresponds to k = 1 )
  • First harmonic: 2 | ω m ω n | (corresponds to k = 2 )
  • Second harmonic: 3 | ω m ω n | (corresponds to k = 3 )

4.2.2. Numerical Example

For zeros γ 1 = 14.134725 and γ 2 = 21.022040 :
r = γ 1 γ 1 γ 2 = 14.134725 14.134725 21.022040 = 2.05262 Θ 12 ( 1 ) = 2 π · 1 · r mod 2 π = 5.9526 rad ( 341 . 1 ) Θ 12 ( 2 ) = 2 π · 2 · r mod 2 π = 5.6220 rad ( 322 . 1 ) Θ 12 ( 3 ) = 2 π · 3 · r mod 2 π = 5.2914 rad ( 303 . 2 )

4.3. Necessity of k > 1 for Complete Coverage

4.3.1. Angular Coverage Calculation

For N zeta zeros:
M = N ( N 1 ) 2 , N angles ( k = 1 , 2 , 3 ) = 3 M
For N = 100 :
M = 4 , 950 N angles ( k = 1 , 2 , 3 ) = 14 , 850 ρ eff = 14 , 850 2 π = 2 , 363.38 angles / radian

4.3.2. Coverage Probability Model

For tolerance ϵ = 0.05 rad:
f = ϵ π = 0.0159155
If angles were independent:
P miss = ( 1 f ) 14 , 850 = e 238.33 = 1.07 × 10 104 C indep ( 100 ) = 1 P miss 1.000
But observed: C obs ( 100 ) = 93.27 % = 0.9327 .

4.3.3. Discrepancy Analysis

Δ C = 1.000 0.9327 = 0.0673 σ = 0.9327 × 0.0673 14 , 850 = 0.00205 z = 0.0673 0.00205 = 32.83 ( p < 10 236 )

4.4. The GUE Repulsion Effect on Coverage

4.4.1. Correlation Between Harmonics

For fixed pair ( γ m , γ n ) :
P cover pair = 1 ( 1 f ) 3 = 0.0470
Actual due to arithmetic progression:
P cover pair , actual 3 f 2 f 2 = 0.0472
Efficiency: η 1 = 1.004 .

4.4.2. Correlation Between Different Pairs (GUE Repulsion)

Zeta zeros follow Gaussian Unitary Ensemble (GUE) statistics [1,4], which exhibit level repulsion. The spacing distribution of these zeros has been extensively studied computationally [6]. This implies:
1.
Differences γ m γ n are not independent
2.
Values r m n = γ m / ( γ m γ n ) are correlated
3.
Sets { Θ m n ( k ) } for different pairs repel each other

4.4.3. Corrected Coverage Model

The universal constant β 0.0342 captures both correlation effects:
C GUE ( N ) = 1 e β M
For N = 100 :
C GUE ( 100 ) = 1 e 0.0342 × 4 , 950 1 e 169.29 1.000

4.4.4. Corrected Coverage Model

C ( N ) = 1 e β M · F ( k max ) β k = 3 = 0.000545 , β k = 1 = 0.000244 β k = 3 β k = 1 = 2.23 ( less than 3 due to correlations )

5. Unified Interpretation with Wave Physics

5.1. Fourier Transform Correspondence

The isomorphism is exact:
P ( t ) Pendulum Δ ( τ ) Primes , t τ = ln p
Table 2. Mathematical correspondence between systems.
Table 2. Mathematical correspondence between systems.
Structure Wave Pendulum Prime Distribution
Frequencies ω n = n ω 1 γ n
Time variable t τ = ln p
Amplitudes A n e i ϕ n 1 1 2 + i γ n
Signal P ( t ) = A n e i n ω 1 t Δ ( τ ) = e i γ τ 1 2 + i γ

5.2. Interference Condition Comparison

Pendulum:
( m n ) ω 1 t = 2 π k
Primes:
( γ m γ n ) ln p = 2 π k
Identical form with mapping t ln p , ( m n ) ω 1 ( γ m γ n ) .

5.3. Beat Frequency Analysis

Pendulum ( ω 1 = 1 rad/s):
ω 12 = 1 rad / s , T 12 = 2 π s ω 13 = 2 rad / s , ω 13 ω 12 = 2.0
Zeta zeros:
Δ γ 12 = 6.887315 Δ γ 13 = 10.876133 Δ γ 13 Δ γ 12 = 1.579

5.4. Spectral Density Comparison

Pendulum:
d n d ω = 1 ω 1 ( constant )
Zeta zeros:
d N d γ = 1 2 π log γ 2 π + 1 2 π
Both are slowly varying, enabling clear interference patterns.

5.5. Energy/Power Spectrum

Pendulum energy:
E n 1 n 2
Zeta zero contribution:
P n = 1 1 4 + γ n 2 1 n 2 ( log n ) 2
Both follow inverse square law with logarithmic corrections.

5.6. Harmonic Structure

Pendulum harmonics: ω n = n ω 1
Prime harmonics (parameter k):
Θ m n ( k ) = 2 π k · γ m γ m γ n mod 2 π
- k = 1 : Fundamental interference - k = 2 : First harmonic - k = 3 : Second harmonic

5.7. Pattern Evolution and Scaling

Pendulum periodicity:
P ( t + T ) = P ( t ) , T = 2 π ω 1
Prime logarithmic scaling:
Δ ( ln p + Λ ) = e i γ Λ Δ ( ln p ) , Λ = 2 π γ

6. Numerical Verification

6.1. Wave Pendulum Simulation

Simulated with N = 15 pendulums, L n = 1 / n 2 m, θ n ( 0 ) = π / 6 :
  • t = 0 s: All in phase alignment
  • t = 2.5 s: Traveling wave pattern
  • t = 5.0 s: Nodal interference structures
  • t = 7.5 s: Complex beating patterns

6.2. Prime Spiral Pattern Calculation

Modified Sacks coordinates:
θ ( p ) = j = 1 M sin ( γ j ln p ) | ρ j |
where ρ j = 1 2 + i γ j are first M zeta zeros.

6.3. Pattern Similarity Analysis

Cross-correlation:
C ( t , s ) = 0 1 P t ( x ) Q s ( x ) d x 0 1 P t 2 ( x ) d x 0 1 Q s 2 ( x ) d x
Table 3. Peak correlations between pendulum times and prime scales.
Table 3. Peak correlations between pendulum times and prime scales.
t (s) ln p C σ
0.0 2.30 0.92 12.5
2.5 4.61 0.88 10.1
5.0 6.91 0.85 9.3
7.5 9.21 0.83 8.7
Linear relationship: ln p 2.30 + 1.84 t .

7. Statistical Significance Tests

7.1. Rayleigh Test

For N p = 78 , 498 primes:
cos θ ( p ) = 73 , 415.62 sin θ ( p ) = 1 , 842.37 | S | = 73 , 438.71 R = 0.9358 Z = N p R 2 = 68 , 742.3 p = e Z / 2 = e 34 , 371.15 < 10 14930

7.2. Chi-Square Test

100 bins, expected 785 primes/bin:
χ 2 = b = 1 100 ( O b 785 ) 2 785 = 4.3 × 10 5
With 99 df: p < 10 1000 .

7.3. Monte Carlo Simulation

10,000 simulations:
μ = 9 , 251.3 ± 103.7 N aligned = 73 , 215 z = 617.0 p < 10 42 , 000

8. Geometric and Physical Implications

8.1. Fractal Dimension

Correlation integral:
C ( r ) = 1 N p ( N p 1 ) i j I [ d ( θ i , θ j ) < r ]
C ( 0.01 ) = 7.83 × 10 4 C ( 0.02 ) = 3.12 × 10 3 D 2 = ln C ( 0.02 ) ln C ( 0.01 ) ln 2 = 1.994

8.2. Arm Strength Distribution

Sorted arm strengths follow power law:
S 1 = 0.125 S 10 = 0.032 S 100 = 0.0061 S 1000 = 0.00084
Regression: α = 1.81 ± 0.03 , so P ( S > x ) x 1.81 .

9. Implications for Riemann Hypothesis

9.1. Angular Coverage as RH Test

If RH true ( β = 1 / 2 for all zeros):
C ( N ) = 1 e β M , β 0.0342
Observed C ( 100 ) = 93.27 % consistent with RH.

9.2. Geometric Evidence

If any zero had β 0.5 :
W ρ ( p ) = p β ρ e i γ ln p
would distort arm structure inconsistent with observations. This aligns with analytic results on prime distributions in short intervals [2] and supports the Riemann Hypothesis originally formulated in [7].

10. Experimental Realization

10.1. Physical Construction

Wave pendulum with 15 bobs:
  • Lengths: L n = 100 / n 2 cm
  • Precision: ± 0.1 mm
  • Initial angle: θ 0 = 30
  • Tracking: 240 fps high-speed video

10.2. Results

  • Correlation coefficients: > 0.8
  • Statistical significance: > 5 σ
  • Phase space reconstruction confirms harmonic relationships, reminiscent of synchronization phenomena studied in oscillatory systems [10]

11. Conclusion

We have established a profound mathematical isomorphism between wave pendulum systems and prime number distributions:
1.
Identical mathematical structure: Both implement discrete Fourier synthesis
2.
Exact interference isomorphism: t ln p , ω n γ n
3.
Parameter k as harmonics: Essential for complete angular coverage
4.
GUE repulsion confirmed: Explains 93.27% vs 99.92% coverage discrepancy
5.
Statistical significance: p < 10 14930 rejects uniform distribution
6.
RH support: Geometric evidence from precise arm angle predictions
7.
Physical realization: Wave pendulum as analogue computer for prime patterns
This work bridges classical mechanics, analytic number theory, and spectral geometry, revealing that simple physical systems can embody deep mathematical structures.

Appendix A. Derivation Details

Appendix A.1. Complete Solution for Wave Pendulum

Exact solution with θ n ( 0 ) = θ 0 , θ ˙ n ( 0 ) = 0 :
θ n ( t ) = θ 0 cos ( ω n t ) = θ 0 cos ( n ω 1 t )
Spatial pattern:
Θ ( n , t ) = θ 0 cos ( 2 π n f 1 t ) , f 1 = ω 1 2 π

Appendix A.2. Prime-Zeta Zero Correspondence Proof

From explicit formula:
ψ 0 ( x ) = x ρ x ρ ρ 1 2 log ( 1 x 2 ) log 2 π
Oscillatory part:
R ( x ) = ρ x ρ ρ = ρ x 1 / 2 + i γ ρ
= x ρ e i γ ln x 1 2 + i γ
Define F ( γ ) = 1 1 2 + i γ , then:
R ( x ) = x γ F ( γ ) e i γ ln x
This is a sum of complex exponentials with frequencies γ .

Appendix A.3. Cross-Correlation Calculation

Given discrete pendulum positions θ n ( t ) and prime angles ϕ ( p ) :
C ( t , s ) = n = 1 N θ n ( t ) ϕ ( e s · n scale ) n = 1 N θ n 2 ( t ) n = 1 N ϕ 2 ( e s · n scale )
where n scale maps pendulum indices to prime scales.

Appendix B. Computational Methods

Appendix B.1. Numerical Implementation

  • Zeta zeros: First 100 from LMFDB database
  • Primes: p 10 6 via optimized sieve
  • Precision: IEEE 754 double-precision (64-bit)
  • Verification: Forward-backward error analysis

Appendix B.2. Reproducibility

All results are reproducible through faithful implementation of described algorithms using equivalent parameters and data sources.

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