{
  "name": "Brownian spread of spheres in water at 20 °C, and a non-motile E. coli",
  "desc": "Stokes–Einstein diffusion coefficients for smooth spheres 0.2–100 µm across in water at 20 °C, with the root-mean-square spread along one axis in 1 s and 60 s and the time to spread each sphere's own diameter, plus the diffusion constant stated for a non-swimming E. coli; one claim per row, with its basis and source",
  "lic": "CC BY 4.0",
  "lic_url": "https://creativecommons.org/licenses/by/4.0/",
  "by": "Ants, Cells & Atoms",
  "url": "https://antscellsandatoms.com/scale/brownian-motion/",
  "from": [
    "CODATA 2022 Boltzmann constant",
    "media/water-properties.csv (shared file; viscosity of water at 20 °C, IAPWS R12-08)",
    "media/diffusion-distance.csv (shared file; the 1 µm sphere row, checked to match)",
    "Lauga & Powers 2009 (E. coli value)",
    "Pearle et al. 2010 (pollen grain and amyloplast sizes)",
    "Perrin 1913 (mean square spread 2Dt)"
  ],
  "how": "Compiled by Ants, Cells & Atoms from the data listed",
  "data_by": [
    "CODATA 2022 recommended values, NIST Standard Reference Database 121: Boltzmann constant 1.380649e-23 J/K (exact), https://physics.nist.gov/cgi-bin/cuu/Value?k, retrieved 2026-10-25",
    "Viscosity of liquid water at 20 °C, 1.0016 mPa·s: International Association for the Properties of Water and Steam, IAPWS R12-08 (2008), https://iapws.org/technical-guidance/release/viscosity; value computed 2026-10-24 (shared file water-properties.csv)",
    "Lauga E, Powers TR 2009, Reports on Progress in Physics 72:096601 (preprint arXiv:0812.2887), https://doi.org/10.1088/0034-4885/72/9/096601: diffusion constant of a non-motile E. coli about 0.1 µm²/s; read 2026-10-25",
    "Pearle P, Collett B, Bart K, Bilderback D, Newman D, Samuels S 2010, American Journal of Physics 78:1278 (preprint arXiv:1008.0039), https://doi.org/10.1119/1.3475685: Clarkia pollen about 100 µm across, amyloplast and spherosome sizes, the rough 0.2 µm visibility estimate at 370 times; read 2026-10-25",
    "Perrin J 1913, Les Atomes (Paris: Félix Alcan), chapter IV, public domain (author died 1942), https://fr.wikisource.org/wiki/Les_Atomes/IV: mean square spread 2Dt; 500 displacements of grains 0.367 µm in radius, e = 7.84 µm in 30 s; viscosity 0.01 poise and N = 68.8e22 for series VII; read 2026-10-25",
    "Picoplankton class limits 0.2–2 µm: Hirata T et al. 2011, Biogeosciences 8:311, CC BY 3.0, https://doi.org/10.5194/bg-8-311-2011, restating Sieburth, Smetacek & Lenz 1978 (shared file plankton-size-classes.csv), retrieved 2026-10-24"
  ]
}