Empirical Earth · Gravity, Buoyancy & the Air

"It's just density and buoyancy" — the gravity substitute

The claim

“It’s all density and buoyancy — no attractive force needed.”

What is measured

Things rise or sink by density, but only because gravity pulls the denser fluid down hardest. Buoyancy is gravity at work, not a rival to it.

What would show this is wrong

dense objects spontaneously rising in still air, or density failing to predict what floats and what sinks.

Sources

  1. H. Cavendish (1798), "Experiments to determine the Density of the Earth." Philosophical Transactions of the Royal Society — torsion-balance measurement of G. CODATA value G = 6.674×10⁻¹¹. Ph link
  2. Tests of General Relativity. Eddington (1919, light bending); Pound & Rebka (1959, redshift, Phys. Rev. Lett.); Touboul et al. / MICROSCOPE (2017, equivalence principle, PRL); Abbott et al. link
  3. Archimedes' principle & buoyancy. Buoyant force F = ρ fluid · V · g; floating/sinking is gravity acting through a density difference, not an alternative to it. Archimedes' principle . link
  4. Katabatic winds: cold, dense air flowing downhill under gravity. Britannica defines a katabatic wind as one that blows down a slope because of gravity : air chilled over high terrain becomes link
  5. Cape Denison — the ‘Home of the Blizzard.’ Guinness World Records notes the fastest katabatic winds occur around coastal Antarctica; at Cape Denison, Commonwealth Bay, Douglas Mawson’s 1911– link
  6. The equivalence principle, tested to 10 −15 . The MICROSCOPE satellite compared the fall of titanium and platinum test masses in orbit and found their accelerations equal to about one part i link
  7. Archimedes, On Floating Bodies (c. 250 BC). The first known work on hydrostatics. Archimedes derives the law of buoyancy and also proves that a fluid settles into a spherical surface about a link
  8. Psyche’s Mars gravity assist, May 2026. On May 15, 2026, NASA’s Psyche spacecraft passed within about 2,864 miles (4,609 kilometers) of Mars and used the planet’s gravity to gain roughly 1,0 link
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