Empirical Earth · Gravity, Buoyancy & the Air

The vacuum chamber — everything falls together

In a vacuum a feather and a bowling ball fall together at 9.81 m/s²; with no fluid present, buoyancy cannot act — so it is a consequence of gravity, not a replacement.

The claim

“Gravity isn’t real — things fall by density and buoyancy, not a pulling force.”

What is true

Density and buoyancy do decide what rises and what sinks. A cork comes up and a stone goes down for exactly the reason the claim gives.

What is measured

Remove the air and a feather and a bowling ball fall together, at 9.81 m/s² on Earth and ~1.62 m/s² on the Moon. With no fluid present, density and buoyancy have nothing to act on, yet everything still falls. Buoyancy is a result of gravity, not a substitute for it.

What would show this is wrong

any object that refuses to fall, or two objects of different density falling at measurably different rates, inside a hard vacuum.

Sources

  1. Falling in a vacuum — NASA’s largest vacuum chamber. In NASA’s Space Power Facility (about 30.5 × 37.2 m, the world’s largest vacuum chamber), a bowling ball and a feather dropped together s link
  2. Apollo 15 hammer–feather drop. On 2 August 1971, Commander David Scott dropped a geological hammer and a falcon feather on the airless Moon; both struck the surface together, confirming Gali link
  3. The equivalence principle tested to 1 part in 10 15 . The MICROSCOPE satellite (CNES/ESA) compared the free-fall of platinum and titanium test masses in Earth orbit; its 2022 final results f link
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