ChandlerWobble

Chandler wobble: data tests, and what they overturned

Reconciled 2026-10-23. The argument these tests support: cw_synchronized_wobble.md. Every number here is produced by a script in this directory (listed at the end). §8 records the claims made earlier in this work that the tests withdrew.

1. The two data sets

Raw IERS polar motion. These are the IERS Rapid Service daily x and y (USNO finals2000A.all, measured rows only, 1973.0–2026.8), averaged into 0.05-yr bins. fetch_eop.py downloads them to data/, which is not in the repository. Polar motion is analysed as the complex series p = x − iy, in which the CW turns prograde (positive frequency). Two other sources could not be used: the IERS datacenter rejected scripted downloads, and the Paris Observatory server (C01, C04) timed out. So nothing before 1973 has been checked against raw data.

../cw.dat. This is a processed x-pole series, 1935–2018.6 at 0.05 yr, of unknown provenance. Over 1973–2018 it equals −0.334 x + 0.05 y (r = −0.967 with x alone), but with signs of further processing:

2. The 1 ∓ CW side peaks of cw.dat are products of its processing (cw_sidebands.py, cw_eop_closure.py, cw_peaks.py)

What cw.dat shows. Peaks at 0.157 and 1.844 /yr, about 0.06–0.08 of the CW in amplitude, with phase closure D₁ = φ(f+1) + φ(f−1) − 2φ(f) = 16° ± 19°. That is the signature of amplitude modulation (0°), not phase modulation (180°), and the same in both halves of the record. Read as Earth physics, it would mean a ±14% annual swing in the wobble’s amplitude.

Raw polar motion does not have them. Amplitudes are relative to the CW line:

window raw p, upper sideband (+1.843) raw x, upper / lower cw.dat, upper / lower
1973–1990 0.010 0.011 / 0.001 0.064 / 0.064
1990–2026 0.0003 0.004 / 0.038 0.032 / 0.048
1973–2018.6 0.005 0.009 / 0.016 0.033 / 0.055

The raw phase closures are noise (spreads of 70–160°). The upper sideband sits in a clean part of the raw spectrum, and there it is 6–100 times weaker in amplitude than in cw.dat. Line by line over 1973–2018, cw.dat ÷ (−0.334 × raw x):

CW annual semiannual 2 − CW 1 − CW 1 + CW 2 + CW 1.5 3.0
1.00 1.10 0.10 0.98 3.44 4.11 3.73 3.18 5.41

No fixed (time-invariant) filter jumps from a gain of 1 to 3.4–4.1 at selected lines. Some multiplicative step is involved.

The mechanism: multiplicative cross-terms from a calendar-locked gain. Multiplying a series that contains the CW by anything with an annual period puts equal lines at f_CW ± 1 with closure 0°, the observed signature. A semiannual factor adds 2 ± CW; annual × semiannual adds 3.0. Two candidate products were tested by regression on raw x and y. The table gives line power left over, relative to the CW:

model regressed onto cw.dat 0.157 1.843 3.0
cw.dat itself 2.2 × 10⁻³ 5.6 × 10⁻⁴ 7.5 × 10⁻⁴
a·x + b·y + trend 1.8 × 10⁻³ 4.5 × 10⁻⁴ 7.9 × 10⁻⁴
+ x², y², xy (squared amplitude) 1.7 × 10⁻³ 3.1 × 10⁻⁴ 7.7 × 10⁻⁴
+ seasonal gain on x, y (4 terms) 6.5 × 10⁻⁵ 5.7 × 10⁻⁴ 7.4 × 10⁻⁴
+ annual and semiannual gain (8 terms) 5.7 × 10⁻⁵ 5.6 × 10⁻⁴ 2.2 × 10⁻⁴

Consequence. The --amp-step option of ../cw.py (annual rescaling of the wobble, s = 0.25) reproduces cw.dat, not the Earth. Raw data limit any annual amplitude modulation of the CW to about 1% since 1990. The 2021 satellite result (../ChandlerWobbleForcing.pdf) appears to rest on a similar processed series. Before 1973 is untested.

3. Every peak (cw_peaks.py)

Every local maximum of the cw.dat periodogram above 3 × 10⁻⁴ of the CW power, matched to n₁·CW + n₂ and to the lunar alias lines, and checked against raw p:

peak (/yr) power / CW raw p, prograde / retrograde share left after a·x + b·y (1973–2018) identification verdict
0.843 1 1 / 10⁻⁵ 0.2% CW: draconic B² alias 0.8440 Earth, phase-locked
1.000 0.32 0.39 / 9 × 10⁻⁴ 1.5% annual wobble Earth
0.737–0.748 5.7 × 10⁻³ 1.2 × 10⁻² / 2 × 10⁻⁵ 0.5% Mm: 14 − anomalistic = 0.7448 (tropical B² 0.7365 is 0.008 away) Earth, stationary line (§4)
0.817 0.064 (beside the CW) not resolved — — slow modulation of the CW (§4)
0.940, 0.680 2 × 10⁻³ – 8 × 10⁻³ similar, prograde 3–12% — Earth: broadened CW band
2.0 removed in cw.dat 2.5 mas, steady — semiannual (comb) Earth
0.157, 1.844 4.5 × 10⁻³, 3.7 × 10⁻³ ≤ 2 × 10⁻⁴ 80% 1 ∓ CW processing (§2)
1.524, 2.984 ~10⁻³ ≤ 4 × 10⁻⁵ 50–100% 3CW − 1; 3 processing
1.7–5 (about 30 peaks) 3 × 10⁻⁴ – 1.3 × 10⁻³ 10⁻⁶ – 10⁻⁵ — none cw.dat noise floor, ~100× raw

4. Phase stability: which lines are forced (cw_peaks.py)

A forced line keeps its absolute phase from window to window; a noise peak, or a sidelobe of a changing CW, does not. This is raw p in four 13.5-yr windows, with amplitudes in mas:

line 1973–86 1986–2000 2000–13 2013–27 phase spread p (random phases) best-fit frequency
CW 0.8440 156 177 109 35 ±18° 0.002 0.8435
Mm 0.7448 18 24 26 18 ±34° 0.017 0.7478
tropical B² 0.7365 15 19 20 16 ±54° 0.065 0.7480 (the same peak)
Mm2 0.5105 3 3 7 1 ±141° 0.73 0.494
14 − tropical 0.6317 4 4 8 6 ±135° 0.68 0.621
2 − CW 1.1560 2 1 14 7 ±104° 0.41 1.163
1.1848 3 4 6 4 ±86° 0.25 1.165
semiannual 2.0 3 4 3 1 ±22° 0.005 2.000

The 0.817 /yr feature was once a candidate for the free mode, but its phase is steady. This is cw.dat in windows long enough to separate it from the CW:

windows 0.817 amplitude / CW 0.817 phase 0.871 phase closure with the CW (AM = 0°)
1935–77 / 1977–2018 0.31 / 0.35 48° / 61° (±6°) −149° / −154° 24° / 48°
1935–63 / 1963–91 / 1991–2018 0.45 / 0.13 / 0.42 42° / 26° / 74° (±27°) −146° / −105° / 157° 23° / 42° / 18°

A noise-driven free mode would wander. This feature holds its phase and closes with the CW like amplitude modulation, so it reads as a slow (~37-yr) modulation of the forced CW. With only two or three independent windows, that reading is suggestive.

5. Joint chance of the two locks (cw_joint_lock.py)

Both lines are named in advance from the alias rule, so there is no look-elsewhere penalty. The null model is a free wobble (432.3 d) excited by white noise, with a small white floor, analysed in the same four windows (40,000 runs per Q):

null model CW lock Mm lock both locks both + Mm amplitude steady
Q = 50 0.080 0.018 0.0014 ~5 × 10⁻⁵ (2 hits)
Q = 85 0.157 0.018 0.0024 ~1.5 × 10⁻⁴ (6 hits)
Q = 150 0.282 0.017 0.0050 ~1 × 10⁻⁴ (4 hits)

The amplitude criterion uses the observed value as its threshold, and the last column rests on few hits. With three 18-yr windows the CW lock alone has p ≈ 0.05.

6. Line strengths and the bandpass (cw_bandpass.py)

The device has to produce each line at its observed strength:

7. Open checks

8. Claims withdrawn during this work

earlier claim status where
The 1 ∓ CW satellites are amplitude-modulation products of the Earth’s wobble; they measure a ±14% N/S balance, largest in early December withdrawn: they come from cw.dat’s processing §2
--amp-step 0.25 makes the model match the observed sidebands it matches cw.dat, not the Earth; default 0 §2
The 0.737 peak is the tropical B² alias and is not a forced line corrected: it is a stationary Mm line at 0.7448 §4
Mm is 15× too strong for the distance modulation resolved: an artifact of fixing f₀ = 432 d, Q = 85 and sharp pulses §6, lead §3
The natural period is ≈ 450 d, with 0.817 as the free mode and a 37-yr free/forced beat withdrawn: with pulse shape free, f₀ ≈ 425–440 d; 0.817 is phase-steady §4, lead §3
Low Q (single digits) is allowed once the wobble is forced bounded: Q ≳ 30, set by the 2 − CW line lead §3
CW counter-torque from a finite-difference inverse corrected: computed exactly in the frequency domain cw_counter_torque.py
The peak near 1.16 /yr is the draconic comb partner 2 − CW (1.1560) re-identified: it is F − M on the annual harmonic, 1 + (F − M) = 1.1668 ≈ 7/6, phase-steady (±31°); 2 − CW wanders cw_suppression.md §6.2
The Kittel (nanomagnet) mode as the working analog kept only as a mathematical identity; rotating machinery is the analog lead §1, cw_magnetized_spheroid.md

Scripts

script what outputs
fetch_eop.py download raw IERS polar motion data/finals2000A.all
cw_sidebands.py cw.dat sideband phase closure (the original AM reading) cw_spheroid_sidebands.png, cw_sidebands.json
cw_eop_closure.py raw IERS against cw.dat: closures, sense test, line gains, seasonal residual cw_eop_closure.png, .json
cw_peaks.py every peak; processing models; phase stability; blog lines; the 0.817 feature cw_peaks.png, .json
cw_joint_lock.py joint chance of the CW and Mm locks; Mm strength under fixed resonance cw_joint_lock.json
cw_bandpass.py free bandpass fitted to the line set cw_bandpass.png, .json