{
  "slug": "the-proton-that-stayed-small",
  "title": "The Proton That Stayed Small",
  "href": "/strata/the-proton-that-stayed-small/",
  "field": "atomic physics and precision spectroscopy",
  "claim": {
    "statement": "we find rₚ = 0.84184(67) fm, which differs by 5.0 standard deviations from the CODATA value of 0.8768(69) fm.",
    "claimants": "Randolf Pohl, Aldo Antognini, François Nez, Fernando D. Amaro, François Biraben, João M. R. Cardoso, Daniel S. Covita, Andreas Dax, Satish Dhawan, Luis M. P. Fernandes, Adolf Giesen, Thomas Graf, Theodor W. Hänsch, Paul Indelicato, Lucile Julien, Cheng-Yang Kao, Paul Knowles, Eric-Olivier Le Bigot, Yi-Wei Liu, José A. M. Lopes, Livia Ludhova, Cristina M. B. Monteiro, Françoise Mulhauser, Tobias Nebel, Paul Rabinowitz, Joaquim M. F. dos Santos, Lukas A. Schaller, Karsten Schuhmann, Catherine Schwob, David Taqqu, João F. C. A. Veloso and Franz Kottmann",
    "citation": "Randolf Pohl, Aldo Antognini, François Nez, Fernando D. Amaro, François Biraben, João M. R. Cardoso, Daniel S. Covita, Andreas Dax, Satish Dhawan, Luis M. P. Fernandes, Adolf Giesen, Thomas Graf, Theodor W. Hänsch, Paul Indelicato, Lucile Julien, Cheng-Yang Kao, Paul Knowles, Eric-Olivier Le Bigot, Yi-Wei Liu, José A. M. Lopes, Livia Ludhova, Cristina M. B. Monteiro, Françoise Mulhauser, Tobias Nebel, Paul Rabinowitz, Joaquim M. F. dos Santos, Lukas A. Schaller, Karsten Schuhmann, Catherine Schwob, David Taqqu, João F. C. A. Veloso and Franz Kottmann. The size of the proton. Nature 466, issue 7303, 213-216 (8 July 2010). DOI: 10.1038/nature09250.",
    "year": 2010,
    "headline_as_printed": "rₚ = 0.84184(67) fm, differing by 5.0 standard deviations from 0.8768(69) fm."
  },
  "records": [
    {
      "file": "data/claim-2010.json",
      "role": "claimant-data",
      "name": "Historical transition energy and equation coefficients",
      "url": "https://www.nature.com/articles/nature09250",
      "licence": "Original attributed transcription of factual published numbers. Source article: copyright 2010 Macmillan Publishers Limited, all rights reserved; no publisher PDF or figure redistributed.",
      "licence_url": "https://www.nature.com/articles/nature09250",
      "retrieved": "2026-09-22",
      "sha256": "9f1695112356952ffcaf6ff352705d1d52e9da9e34fe181900b25e1ee62a8731",
      "units": 1
    },
    {
      "file": "data/control-2026.json",
      "role": "control-data",
      "name": "Published corrected component frequencies, correction and uncertainty inputs",
      "url": "https://www.nature.com/articles/s41586-026-10124-3",
      "licence": "CC BY 4.0, attributed numerical transcription or unchanged source file; changes described in NOTICE.txt.",
      "licence_url": "https://www.nature.com/articles/s41586-026-10124-3",
      "retrieved": "2026-09-22",
      "sha256": "656a76d571ea694c55be35604e8a304b4538a5b2dbe0a761656baf2c56e72520",
      "units": 2
    },
    {
      "file": "data/constants-2022.json",
      "role": "reference",
      "name": "CODATA 2022 numerical constants",
      "url": "https://physics.nist.gov/cuu/pdf/JPCRD2022CODATA.pdf",
      "licence": "Original attributed numerical transcription. Source publication prints copyright 2025 U.S. Secretary of Commerce on behalf of the United States, all rights reserved; no PDF redistributed.",
      "licence_url": "https://physics.nist.gov/cuu/pdf/JPCRD2022CODATA.pdf",
      "retrieved": "2026-09-22",
      "sha256": "6e45420715d20737861344c8a1baac4ac5f4670c9cf7e3c3e986ce56b5e4d66e",
      "units": 5
    },
    {
      "file": "data/context.json",
      "role": "reference",
      "name": "Independent result and dated contextual facts",
      "url": "https://journals.aps.org/prl/abstract/10.1103/lgl2-6cb8",
      "licence": "Factual result and bibliographic transcription only. Bullis publisher: copyright 2026 APS. CODATA publication retains its stated rights. Miller preprint linked, not redistributed.",
      "licence_url": "https://journals.aps.org/prl/abstract/10.1103/lgl2-6cb8",
      "retrieved": "2026-09-22",
      "sha256": "bee39d730b60f92dc5dc278463b81686ddbf158b394a6feb2797daf605eaef13",
      "units": 3,
      "source_urls": [
        "https://journals.aps.org/prl/abstract/10.1103/lgl2-6cb8",
        "https://physics.nist.gov/cuu/pdf/JPCRD2022CODATA.pdf",
        "https://arxiv.org/abs/2604.15546v2"
      ]
    },
    {
      "file": "data/rydberg.json",
      "role": "reference",
      "name": "Published Rydberg constants paired with proton radii (CODATA 2006, 2026 Garching, 2026 Bullis, CODATA 2022)",
      "url": "https://arxiv.org/abs/0801.0028",
      "licence": "Factual numerical transcription with attribution. CODATA 2006 (Rev. Mod. Phys., read in arXiv:0801.0028v1) and CODATA 2022 retain their stated rights; Bullis copyright 2026 APS; the Garching values are from a CC BY 4.0 article. No source file is redistributed.",
      "licence_url": "https://arxiv.org/abs/0801.0028",
      "retrieved": "2026-09-22",
      "sha256": "0ede1e9e7e7d7453b274585eeba3cb38ddc837164f6beae68f338cf122e0c59a",
      "units": 4,
      "source_urls": [
        "https://arxiv.org/abs/0801.0028",
        "https://www.nature.com/articles/s41586-026-10124-3",
        "https://journals.aps.org/prl/abstract/10.1103/lgl2-6cb8",
        "https://physics.nist.gov/cuu/pdf/JPCRD2022CODATA.pdf"
      ]
    },
    {
      "file": "data/single-scan.json",
      "role": "control-data",
      "name": "Corrected fitted frequencies for the illustrated scan, selected worksheet",
      "url": "https://media.springernature.com/original/springer-static/esm/art%3A10.1038%2Fs41586-026-10124-3/MediaObjects/41586_2026_10124_MOESM4_ESM.xlsx",
      "licence": "CC BY 4.0, attributed numerical transcription or unchanged source file; changes described in NOTICE.txt.",
      "licence_url": "https://www.nature.com/articles/s41586-026-10124-3",
      "retrieved": "2026-09-22",
      "sha256": "9aa7df1d666d186a64d04778f15dd354033dffa08589e68b679f4e4cd9aab4c8",
      "units": 16
    },
    {
      "file": "data/comparison.csv",
      "role": "reference",
      "name": "Unchanged Figure 1 radius comparison inventory",
      "url": "https://media.springernature.com/original/springer-static/esm/art%3A10.1038%2Fs41586-026-10124-3/MediaObjects/41586_2026_10124_MOESM3_ESM.csv",
      "licence": "CC BY 4.0, attributed numerical transcription or unchanged source file; changes described in NOTICE.txt.",
      "licence_url": "https://www.nature.com/articles/s41586-026-10124-3",
      "retrieved": "2026-09-22",
      "sha256": "fb66207047dcabf2c7895e28095f9021ac30878fccbf4b4c8f72280957eadc09",
      "units": 10
    }
  ],
  "anchor": {
    "what": "Invert the published measured muonic transition energy with the 2010 equation using the shared radius-inversion backend.",
    "expected": "0.84184 ± 0.00067 fm",
    "computed": "0.84183113 fm; ± 0.00067073 fm; 5.044 σ",
    "agrees": true,
    "tolerance": "Centre 0.000030 fm; uncertainty 0.000015 fm; discrepancy 0.05 σ. Independent half-last-unit variations in printed coefficients, energy and uncertainties justify these bounds."
  },
  "control": {
    "name": "Electronic 2S-6P centroid constrained by measured 1S-2S, with a declared leading finite-size response",
    "citation": "Lothar Maisenbacher, Vitaly Wirthl, Arthur Matveev, Alexey Grinin, Randolf Pohl, Theodor W. Hänsch and Thomas Udem, Sub-part-per-trillion test of the Standard Model with atomic hydrogen. Nature 650, 845-851 (11 February 2026). DOI: 10.1038/s41586-026-10124-3.",
    "computed": "730,690,248,610.79 kHz; 0.8406 ± 0.00145 fm",
    "as_printed": "730,690,248,610.79 kHz; 0.8406 ± 0.0015 fm"
  },
  "power": {
    "grade": "A-injection",
    "planted": "Actual 2010 radius contrast 0.8768 → 0.84184 fm: a copy of both measured component frequencies is reset by +13.1 kHz to the old radius, then −12.6 kHz is added to both frequency fields of that copy.",
    "recovered": "The unmodified control returns 0.8418 fm ± 0.0015 fm (squared-radius change −0.0601 fm², centroid moved −12.6 kHz). Read off its output, the planted copy sits 24.6 σ from the old-radius centroid in the control's own uncertainty; the old-radius copy sits 0.0 σ and is not flagged. Against the uncertain CODATA 2006 radius the planted result differs by 4.958 σ.",
    "verdict": "the control COULD have confirmed the claim",
    "scope": "Grade A injection at the published-frequency level. It trusts the reported frequency uncertainties and corrections. It does not test photon detection, scan selection, technical noise or the completeness of the systematic budget."
  },
  "null_through_claimant_method": {
    "applicable": false,
    "what": "This page does not implement the original photon-count likelihood or resonance search. White noise passed through a radius inversion would not test how often that procedure finds a false resonance.",
    "result": "Not run: the original resonance-search pipeline is outside this measurement-level reconstruction."
  },
  "verdict": {
    "category": "VINDICATED",
    "as_of": "2026-09-22",
    "sources": [
      "Lothar Maisenbacher, Vitaly Wirthl, Arthur Matveev, Alexey Grinin, Randolf Pohl, Theodor W. Hänsch and Thomas Udem, Sub-part-per-trillion test of the Standard Model with atomic hydrogen. Nature 650, 845-851 (11 February 2026). DOI: 10.1038/s41586-026-10124-3.",
      "R. G. Bullis, W. L. Tavis, M. R. Weiss, J. Orellana Cisneros, A. J. Cheeseman, U. D. Jentschura and D. C. Yost, Precision Spectroscopy of 2S-nS Transitions in Atomic Hydrogen: A Determination of the Proton Charge Radius. Physical Review Letters 136, 123001 (23 March 2026). DOI: 10.1103/lgl2-6cb8."
    ],
    "scope": "VINDICATED applies to the small-radius scale, independently supported by electronic hydrogen. It does not preserve every digit of the original theory, establish a new force, or settle every scattering analysis.",
    "would_change": "A verified correction that moves these electronic frequency determinations back to the former large radius, or independent measurements with controlled uncertainties establishing a reproducible difference between muonic and electronic radii, would change this verdict."
  },
  "decided_by": "independent-replication",
  "years_to_decision": 16,
  "choices": [
    {
      "id": "state",
      "label": "Observation state",
      "options": [
        "measured",
        "baseline",
        "planted"
      ],
      "default": "measured",
      "affects": [
        "component frequencies",
        "centroid",
        "inferred radius",
        "historical disagreement"
      ],
      "inert": false
    },
    {
      "id": "comparator",
      "label": "Historical comparator",
      "options": [
        "2006",
        "2014"
      ],
      "default": "2006",
      "affects": [
        "comparison radius",
        "comparison uncertainty",
        "historical disagreement"
      ],
      "inert": false
    },
    {
      "id": "shared",
      "label": "Shared frequency shift in kHz",
      "options": [
        -15,
        0,
        15
      ],
      "default": 0,
      "affects": [
        "centroid",
        "inferred radius"
      ],
      "inert": false
    },
    {
      "id": "difference",
      "label": "Difference frequency shift in kHz",
      "options": [
        -5,
        0,
        5
      ],
      "default": 0,
      "affects": [
        "fine-structure residual"
      ],
      "inert": false
    },
    {
      "id": "subset",
      "label": "Single-scan velocity groups",
      "options": [
        "all",
        "slow",
        "fast"
      ],
      "default": "all",
      "affects": [
        "intercept",
        "intercept uncertainty",
        "subset sensitivity"
      ],
      "inert": false
    },
    {
      "id": "scale",
      "label": "Inflation of the published centroid measurement uncertainty",
      "options": [
        1,
        8,
        9,
        20
      ],
      "default": 1,
      "affects": [
        "planted separation",
        "power verdict"
      ],
      "inert": false
    }
  ],
  "headline": "Ordinary hydrogen puts the proton at 0.8406 fm. Planted with the 2010 contrast, its control lands 24.6 of its own standard uncertainties from the old radius, a sensitivity margin that falls to 4.96 σ once the old value’s uncertainty is counted, while its fine-structure check stays blind to the same shift.",
  "novelty": "we searched the Artificial Wasteland built index, the Nature source-data records and web searches for proton-radius interactive fine-structure and power-injection tools on 2026-09-22 and did not find an interactive reconstruction that places the 2010 radius contrast in the blind direction of the 2026 fine-structure check while also showing the radius-sensitive centroid.",
  "ledger": {
    "claim_reproduced": {
      "value": true,
      "assertion": "anchor:shared-inversion-and-corrupted-energy"
    },
    "control_computed": {
      "value": true,
      "assertion": "control:components-centroid-radius"
    },
    "control_can_confirm": {
      "value": true,
      "assertion": "power:frequency-edits-same-control"
    },
    "rendered_figures_asserted": {
      "value": true,
      "assertion": "surface:published-static-and-browser-readouts"
    },
    "choices_are_live": {
      "value": true,
      "assertion": "choices:all-parameters-and-blind-outputs"
    },
    "planted_fault_caught": {
      "value": true,
      "assertion": "fault:one-component-before-inference"
    },
    "refusal_asserted": {
      "value": true,
      "assertion": "refusal:radius-domain-and-invalid-observations"
    },
    "provenance_pinned": {
      "value": true,
      "assertion": "provenance:sha256-frozen-bytes"
    },
    "verdict_dated": {
      "value": true,
      "assertion": "verdict:scope-date-two-experiments"
    }
  },
  "surface": {
    "static_visible_sha256": "9a914f9467c7e4bdd241e62d306858e9fcb20f5ec2efa70c05e30bbf86423053",
    "interface_sha256": {
      "report.js": "7a835da13b09aa3c89e446230ca105c20f4290678462134dfaeea5175642ae25",
      "render.js": "f87fc92886140780547240e56d5099418c8c35f5f9d8e070728455bbe659be95",
      "page.js": "746037c9515b2612387753e31395f8fcf876be64f13f0fdd79d3e6c376bda189"
    }
  },
  "research_files": [
    {
      "file": "data/figure2-source.xlsx",
      "url": "https://media.springernature.com/original/springer-static/esm/art%3A10.1038%2Fs41586-026-10124-3/MediaObjects/41586_2026_10124_MOESM4_ESM.xlsx",
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}