Everyone is taught the answer is no. In a vacuum, that answer is exact in the ordinary test-body model. In air, keep shape and size fixed and the heavier body really does arrive first. The air pushes equally hard on both equal silhouettes; the heavier one has more weight with which to ignore it.
The tower below is a stage, not a claim that Galileo performed the legendary Pisa drop. Press Pisa + air. Two 10 cm spheres leave together. Then remove the air and watch a nearly five-metre separation become zero.
model time: 3.393 s
iron, 4.12 kg
3.393 s
terminal 133.7 m/s
oak, 0.37 kg
3.570 s
terminal 40.1 m/s
gap when winner lands
4.925 m
246.3 finger-breadths
selected world
air
g = 9.80665 m/s²
Same diameter, different mass: the iron sphere wins by 0.178 s.
The air does not know the mass
For the equal-sized spheres, area and drag coefficient are pinned. The bench solves the quadratic-drag equation live:
dv/dt = g - (rho Cd A / 2m)v² vt = sqrt(2mg / rho Cd A)
With fixed Cd A, terminal velocity grows as the square root of mass. That is the regime your eyes usually see. It is not a general licence to compare arbitrary objects: a light dart can beat a heavy parachute. Small dust and droplets can also live in a different, Stokes-drag regime.
The second fall
In Two New Sciences, Galileo asks us to imagine a 100-pound and a 1-pound body falling through 100 braccia. He says the lighter trails by only two finger-breadths when the larger lands.
Press Galileo's claim + air. Treat both as iron spheres, take the pound as the modern avoirdupois pound of 453.59 g, convert 100 braccia to a declared 57 m, and take one finger-breadth as a declared 2 cm. The same model returns 0.942 m, or 47.1 finger-breadths. His claimed 4 cm is smaller by a factor of 23.5.
This is not a reconstructed experiment. Sphere sizes, the braccio conversion, constant Cd = 0.47, and still sea-level air are model choices. Adler and Coulter's 1978 analysis likewise found the famous small separation doubtful. The bench's exact 0.942 m belongs to the assumptions printed here, not to their paper.
The check
Pisa model preset
rho = 1.225 kg/m³ Cd = 0.47 diameter = 0.100 m m = 4.12, 0.37 kg height = 55.86 m
The analytic solution gives terminal speeds 133.679 and 40.060 m/s, landing times 3.39251 and 3.57014 s, and a 4.92519 m gap.
Remove the medium
t = sqrt(2h/g)
At 55.86 m, both read 3.375244 s and the gap is 0.000 m. At 1.6 m with lunar g = 1.62 m/s², both read 1.405457 s.
Free choices and uncertainties: constant density, still air, no buoyancy, spin, wind, or release error; spherical bodies; fixed drag coefficient; material masses rounded as supplied; 453.59 g per pound; 57 m per 100 braccia; 2 cm per finger-breadth. The 4.925 m result is a model output, not a Pisa measurement. NASA's stated 0.03 kg feather mass appears rounded and is not needed to obtain the vacuum equality.
The equality underneath
NASA reports that David Scott released a 1.32 kg hammer and its stated 0.03 kg falcon feather together from approximately 1.6 m on 2 August 1971. In the Moon's near-vacuum they arrived together within the accuracy of the release. The preset computes a model time; it does not pretend NASA measured 1.405457 seconds.
A pedantic, separate-drop footnote: in a two-body calculation the Earth moves toward the dropped object, so a 4.12 kg object's relative acceleration differs from a test particle's by about m/MEarth = 6.9 x 10-25. This is not composition-dependent falling. MICROSCOPE found no such equivalence-principle violation, reporting eta(Ti,Pt) = [-1.5 +/- 2.3(stat) +/- 1.5(syst)] x 10-15.
The claims record8 claims re-read against their sources, 27 September 2026
Written 2026-07-23. Claims re-read against their sources on 2026-09-27: 8 checked, 7 confirmed, 0 wrong, 1 unverifiable. By claims audit 2026-09-27 (outside audit agent; record backfilled from its report by a second agent).
Control-sample audit (research/claims-audit/PREREG.md), 2026-09-27, findings condensed in
research/claims-audit/findings/r3.md. Reader check: none possible; the named verifier is 404 at both
/checks/ paths and absent from the manifest. The repository copy passes 26/0, and the model redone
by hand matches (gap 4.92519 m, Galileo gap 0.94184 m, factor 23.55). The layer was classified
reader-side; git shows no change to it since the audit.
Claims
CONFIRMED Apollo 15: 1.32 kg hammer, 0.03 kg falcon feather, about 1.6 m, "Within the accuracy of the simultaneous release" https://science.nasa.gov/resource/the-apollo-15-hammer-feather-drop/ : matches; the date (2 Aug 1971, EVA-3) is correct though the page does not state it
UNVERIFIABLE Adler and Coulter "likewise found the famous small separation doubtful" https://api.crossref.org/works/10.1119/1.11165 (abstract only; AIP paywall) : the abstract says "it is doubtful if Galileo could have obtained the results claimed in the legend", which concerns the Pisa legend, not specifically the two-finger figure
What was done
[declined] NOT ADDRESSED: MED the placard names research/do-heavier-objects-fall-faster/verify-do-heavier-objects-fall-faster.mjs and says the check reads what the reader is reading, but a stranger cannot get the file (404 at both /checks/ paths); publish it via scripts/publish-checks.mjs.
[declined] NOT ADDRESSED: MINOR/MED the dek (src/content/strata/do-heavier-objects-fall-faster.md:4, repeated in the meta description and ld+json) says Galileo's number is wrong "by a factor of twenty", while the body says 23.5 and the recomputation gives 23.55.
[declined] MINOR the galileo preset uses the avoirdupois pound (45.359237 kg per 100 lb), not declared among the free choices; with the Florentine libbra the factor becomes 25.9: left as is, a minor undisclosed model choice.
[declined] MINOR paraphrase: in Crew and de Salvio the 100 lb and 100 cubit setup is Galileo quoting Aristotle, with two finger-breadths given as an experimental result: left as is, a minor paraphrase.
[declined] MINOR the delft preset calls both balls lead, though 10 kg and 1 kg at 10 cm give densities of about 19,100 and 1,910 kg/m3, and Stevin's balls differed in size: left as is, minor, a label on a preset.
[declined] MINOR Adler and Coulter's doubt is about the Pisa legend, not clearly the two-finger figure: left as is; the full text is paywalled, so the report could not show the page wrong (the UNVERIFIABLE line).
The assay office: what a record is, and every layer re-read so far.