[Summary] (Asimov) The Relativity of Wrong

Dated Sep 1, 1989; last modified on Sun, 18 Sep 2022

The Relativity of Wrong. Isaac Asimov. chem.tufts.edu . Sep 1, 1989.

John, when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.

The Flat Earthers

Earth’s curvature is nearly 0.000126 per mile, which is close to zero.

  • Although the theory is wrong, it happens to be nearly right.
    • The ancient’s instruments couldn’t measure this

The Earth is spherical

Aristotle’s observations that were explainable by a spherical Earth:

  • Certain stars disappeared beyond the Southern Hemisphere as one traveled north, and vice versa
  • The earth’s shadow during a lunar eclipse was always the arc of a circle.
  • Ships disappeared beyond the horizon hull-first in whatever direction they were traveling.


  • The sun cast a shadow of different lengths at different latitudes.
    • Estimated circumference of 25,000 miles

The Earth is an oblate spheroid

Early telescopes showed the sun and the moon as perfect circles. However, later on, Jupiter and Saturn were observed to be distinct ellipses.

Isaac Newton:

  • Just as Aristotle had argued, a massive body would form a sphere under gravity

    • But if it’s rotating, the centrifugal effect would lift its substance against gravity
      • This effect would be greater closer to the equator
  • On the spherical earth, the curvature is 8 inches per mile.

    • On the oblate spheroidal, the curvature varies from 7.973 to 8.027 inches to the mile

The Earth is a Bartlett pear

In 1958, the Vanguard I satellite measured local gravitational pull & therefore the earth’s shape.

  • The equatorial bulge south of the equator was slightly bulgier
  • The South Pole sea level was slightly nearer the center of the earth.

The pear-like deviation from oblate-spheroid perfect was a matter of yards rather than miles, and the adjustment of curvature was in the millionths of an inch per mile.

Appreciating the Ancient Theories

Since the refinements in theory grow smaller and smaller, even quite ancient theories must have been sufficiently right to allow advances to be made.

  • Despite Flat Earth, Greeks' concept of latitude and longitude is still useful
  • Despite earth-centric solar system, Sumerians established the regularity of planetary movements.