Rejected for a long time before being accepted

Some notable scientific hypotheses had been rejected for a long time before being accepted.

  • Heliocentrism
  • Atomism
  • Meteorites as Extraterrestrial Rocks
  • Geological Catastrophes
  • Continental Drift
  • Genes
  • Lichens as Alga-Fungus Symbioses
  • Endosymbiosis
  • Transposons: “Jumping Genes”
  • Chemiosmotic Biological Energy Metabolism
  • Dorsoventral Inversion of Chordates

Their later acceptance was usually the result of later discoveries, sometimes decades or centuries later.

These later discoveries often included resolutions of the difficulties that many of the theories’ critics had pointed out, though not always. Critics of heliocentrism pointed out that stars ought to have parallaxes, and heliocentrists responded by proposing that the stars are very far away, which seemed rather implausible. At least since the late 17th century, heliocentrism was widely accepted, but parallaxes of stars were not successfully measured until 1838, when three astronomers published parallax measurements of three stars. The nearest one of these was nearly 300,000 times farther from the Sun than the Earth is, thus vindicating the great-distance hypothesis.

The acceptance of some of the theories involved conceptual reorganizations, like with continental drift. Instead of continents plowing through oceanic crust, continents drift along with nearby oceanic crust, which gets created and destroyed. Chemiosmotic energy metabolism was another: instead of some chemical intermediate, it is a physical intermediate: hydrogen ions being pumped across a membrane and then returning.

There are sometimes weird ones. In the late 19th cy., the particle theory of light seemed conclusively refuted with the success of the wave theory. But around the turn of the 20th cy., physicists discovered some effects that implied that light also has particle properties, like the photoelectric effect. This was part of the discovery of quantum mechanics, and that discovery also involved discovering that matter particles, like electrons, have wave properties. Wave-particle duality has been well-established for some decades, though with macroscopic entities being mostly particlelike or mostly wavelike.

Finally, in no case was a theory ever accepted by its advocates whining about how closed-minded the mainstream scientific community is. Pseudoscientists and crackpots never tire of whining about that, almost as if that somehow proves the truth of their theories. But as Bertrand Russell had noted, “There are infinite possibilities of error, and more cranks take up unfashionable errors than unfashionable truths.”