Empirical Earth · Rotation & How We Measure It

Michelson — aether, light-speed & Earth's rotation

The claim

“Michelson-Morley’s null result proves a stationary Earth.”

What is measured

Ring-laser gyroscopes sense Earth’s rotation directly at ~15°/hour via the Sagnac effect. It is the same technology that keeps aircraft and phones level.

What would show this is wrong

a ring-laser or interferometer Sagnac signal absent at the latitude-scaled rotation rate.

Sources

  1. Michelson-Morley experiment (1887). A. A. Michelson & E. W. Morley, "On the Relative Motion of the Earth and the Luminiferous Ether," American Journal of Science 34 (1887); preceded by Miche link
  2. Michelson-Gale-Pearson experiment (1925). A. A. Michelson & H. G. Gale, "The Effect of the Earth's Rotation on the Velocity of Light," I & II, Astrophysical Journal 61 (1925) — 1.9 km ring, link
  3. Michelson's speed-of-light measurements & the Pasadena Base. A. A. Michelson, Mount Wilson ↔ Lookout Mountain (~35 km), 1924–26, c ≈ 299,796 km/s; U.S. Coast & Geodetic Survey geodetic basel link
  4. Aberration of light. James Bradley discovered stellar aberration in 1727 — a ~20.5″ annual shift of every star caused by Earth's ~30 km/s orbital velocity combined with the finite speed of l link
  5. Ring-laser gyroscopes & the Wettzell “G” ring. Ring-laser gyroscopes use the Sagnac effect to measure absolute rotation; the 4-meter “G” ring laser at the Geodetic Observatory Wettzell monit link
  6. Modern Michelson–Morley: the isotropy of the speed of light. Laser and optical-cavity versions (Brillet & Hall 1979 onward) bound any direction-dependence of the speed of light; a 2015 rotat link
  7. The Sagnac effect (1913). Georges Sagnac showed that a rotating ring interferometer shifts its fringes in proportion to enclosed area × rotation rate — the basis of the Michelson–Gale–Pearso link
  8. Dayton Miller’s reported ether drift. Dayton C. Miller (1866–1941), an American physicist, repeated the Michelson interferometer experiment for years at Cleveland and on Mount Wilson. He rep link
The full entry, with the working →

This is one card from Empirical Earth, a free reference that states each flat-Earth claim at its strongest and then answers it with sourced measurements. Nothing is for sale and there are no advertisements.