{"product_id":"massratio-proton-electron","title":"Massratio – Proton-to-Electron Mass Ratio \/ 1836.15 Physics Sticker","description":"\u003cp\u003eMassratio is a stone proton giant of The SI Guard with a tiny electron sprite, balanced on a long lever.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eThe proton is about 1836 times heavier than the electron. This dimensionless ratio sets why atoms have a tiny heavy nucleus with a light electron cloud, why nuclei barely move in chemistry (the Born–Oppenheimer approximation), and the ratio of vibrational to electronic energies in molecules. It is measured with Penning-trap mass comparisons and precision spectroscopy of molecular hydrogen ions such as HD⁺.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eμ = m\u003csub\u003ep\u003c\/sub\u003e\/m\u003csub\u003ee\u003c\/sub\u003e = 1836.152 673 426(32)\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eμ: proton-to-electron mass ratio (dimensionless)\u003c\/li\u003e\n\u003cli\u003em\u003csub\u003ep\u003c\/sub\u003e: proton rest mass, measured\u003c\/li\u003e\n\u003cli\u003em\u003csub\u003ee\u003c\/sub\u003e: electron rest mass, measured\u003c\/li\u003e\n\u003cli\u003e(32): standard uncertainty in the last two digits, about 1.7 × 10⁻¹¹ relative\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eValue: CODATA 2022 (NIST). μ is measured, not fixed by the 2019 SI. Astronomers compare molecular lines in distant gas clouds with lab values to test whether μ changes over cosmic time; no change has been found within their limits.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The proton's mass is not the sum of its three quarks. The Higgs-given masses of the up and down quarks supply only about 1% of it; the rest is the energy of the strong interaction (QCD) inside the proton. The electron's mass, by contrast, comes directly from its coupling to the Higgs field.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003eThe stone giant holds the short arm of the lever while the electron sprite sits far out on the glowing ice-blue end. Printed text: \u003cstrong\u003eMASSRATIO\u003c\/strong\u003e with the line \u003cstrong\u003emp\/me = 1836.15\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50963709132903,"sku":"21958700876220678481","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50963709165671,"sku":"32618302860978082942","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50963709198439,"sku":"13760541172625756137","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50963709231207,"sku":"12912935050089786607","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/8130008875844456380_1200.jpg?v=1793664978","url":"https:\/\/pixelatedphysics.com\/zh-hans\/products\/massratio-proton-electron","provider":"Pixelated Physics","version":"1.0","type":"link"}