Estimating Acoustic Peak Positions
in the Cosmic Microwave Background
估算宇宙微波背景輻射
功率譜中的聲學峰位置

Frank Wang  ·  LaGuardia Community College, CUNY

European Journal of Physics   2026
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From a window overlooking Central Park, a mathematician in New York City looks up — past the treetops, past the skyline — at the oldest light in the universe. 從一扇俯瞰中央公園的窗口,一位紐約的數學家抬起頭——越過樹梢,越過天際線——望向宇宙中最古老的光。

He found a simple formula that textbooks had overlooked — and it matches satellite data within 3%. 他找到了一個被教科書忽略的簡潔公式——與衛星數據的吻合度在 3% 以內。

The Oldest Light 最古老的光

The cosmic microwave background (CMB) is relic radiation from the early universe — a snapshot of the moment when light first traveled freely through space. 宇宙微波背景輻射(CMB)是早期宇宙的遺跡輻射——記錄了光第一次在空間中自由傳播的那個瞬間。

t = 0   THE BIG BANG t = 0   大爆炸
The universe begins as a hot, dense plasma of photons, electrons, and protons. 宇宙以高溫、緻密的光子、電子和質子等離子體的狀態開始。
t = 370,000 years   DECOUPLING t = 370,000 年   退耦
Temperature drops to ~3000 K. Atoms form. Light is released and begins its journey across the cosmos. 溫度降至約 3000 K。原子形成。光被釋放,開始穿越宇宙的旅程。
1965   DISCOVERY 1965   發現
Penzias and Wilson detect the CMB — a uniform 2.7 K glow filling the sky in every direction. 彭齊亞斯和威爾遜偵測到 CMB——一道均勻的 2.7 K 微光充滿天空的每個方向。
1992   COBE 1992   COBE 衛星
NASA's COBE satellite detects tiny temperature fluctuations: 1 part in 100,000. The seeds of all cosmic structure. NASA 的 COBE 衛星偵測到微小的溫度波動:十萬分之一。所有宇宙結構的種子。
2018   PLANCK 2018   普朗克衛星
ESA's Planck mission delivers the most precise map of CMB anisotropies — revealing seven acoustic peaks. 歐洲太空總署的普朗克衛星交出最精確的 CMB 各向異性地圖——揭示了七個聲學峰。
2026   THIS PAPER 2026   本論文
Frank Wang proposes a simple formula that estimates all seven peak positions within 3% accuracy. 王教授提出一個簡潔公式,以 3% 以內的精確度估算全部七個峰的位置。

The Power Spectrum 功率譜

When we decompose CMB temperature variations by angular scale, a remarkable pattern of peaks and troughs emerges — acoustic oscillations frozen at the moment of decoupling. 當我們按角尺度分解 CMB 的溫度變化,一組引人注目的峰谷模式浮現——聲學振盪凍結在退耦的那一刻。

Planck 2018 peaks 普朗克 2018 觀測峰 Wang formula: (n−¼)π/θ* 王氏公式:(n−¼)π/θ*

Hover over a peak to compare observed and predicted positions. 將滑鼠移到峰上,可比較觀測值與預測值。

The Overlooked Shift 被忽略的偏移

Existing formulas predict peaks at ln ≈ nπ/θ*, but these systematically miss the observed positions. The first peak is predicted at ℓ = 309 — the actual value is 221. 現有公式預測峰值在 ln ≈ nπ/θ*,但系統性地偏離觀測位置。第一個峰被預測在 ℓ = 309——實際值是 221。

Wang's insight: the power spectrum C is an integral over wave numbers. The extremum of an integral need not coincide with the extremum of its integrand. This is first-year calculus — hiding in plain sight. 王教授的洞見:功率譜 C 是對波數的積分。積分的極值不一定與被積函數的極值重合。這是大一微積分——就藏在眾目睽睽之下。

The peaks of the integral (bottom) are shifted left by π/4 compared to the integrand (top).
This quarter-period shift is the origin of the n − ¼ correction.
積分的峰(下方)比被積函數的峰(上方)向左偏移了 π/4
這個四分之一週期的偏移,就是 n − ¼ 修正的來源。

A Simple Correction 一個簡單的修正

Replace n with n − ¼ in the peak formula, and use the angular acoustic scale θ* = 1/96.35 computed from published cosmological parameters: 在峰值公式中把 n 替換為 n − ¼,並使用從已發表的宇宙學參數計算出的角聲學尺度 θ* = 1/96.35:

n  ≈  (n14)πθ*
Peak n峰 n 1234567
Planck 2018 220.6538.1809.81147.81446.817792075
Formula公式 227.0529.7832.41135.11437.817402043
Error誤差 +2.9%−1.6%+2.8%−1.1%−0.6%−2.2%−1.5%

Cosmic Scales 宇宙的尺度

From six cosmological parameters and the Friedmann equation — numerically integrated with Mathematica — the paper computes these characteristic distances: 從六個宇宙學參數和弗里德曼方程式——用 Mathematica 數值積分——論文計算出以下特徵距離:

Age of the universe, t0 宇宙的年齡,t0 13.79 billion years 137.9 億年
Radius of the observable universe, η0 可觀測宇宙的半徑,η0 46.13 billion light-years 461.3 億光年 The particle horizon — the maximum distance from which light could have reached us 粒子視界——光能抵達我們的最遠距離
Physical time at decoupling, t* 退耦時的物理時間,t* 370,800 years 370,800 年 Often rounded to 380,000 in popular accounts — the paper corrects this 通俗文章常四捨五入為 380,000 年——本文修正了這個數值
Sound horizon at decoupling, r* 退耦時的聲學視界,r* 469,300 light-years 469,300 光年 The fundamental ruler — 143.9 Megaparsecs — imprinted in the CMB 基本標尺——143.9 百萬秒差距——刻印在 CMB 中
Angular acoustic scale, θ* 角聲學尺度,θ* 0.5947° ≈ 1/96.35 About the apparent diameter of the full Moon — the key parameter in the peak formula 約等於滿月的視直徑——峰值公式中的關鍵參數

Published in the European Journal of Physics 發表於歐洲物理期刊

DOI: 10.1088/1361-6404/ae5902

Frank Wang  ·  Department of Mathematics, LaGuardia Community College, CUNY

Numerical computations performed with Mathematica. 數值計算使用 Mathematica 完成。

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