Outdated scientific theory

The obsolete geocentric model of the universe places Earth in the center.

An outdated scientific theory is a scientific theory that was once commonly accepted but is—for whatever reason—no longer considered the most complete description of reality by established science, or well a verifiable theory that has been proven false. This label does not include theories that have not yet gained wide support in the scientific community—protoscience or fringe science—nor theories that were never widely accepted or were only supported in very specific countries, such as Lysenkoism.

In some cases, the theory has been thrown out completely. In others, the theory remains useful because it provides a description that is "good enough" for a particular situation, and that is easier to use than the full theory—often because the latter is too mathematically complex to be usable. Karl Popper suggested that all scientific theories should be testable or else they could not be tested experimentally. Anything that cannot be proven false experimentally would therefore be an axiom and have absolute status, beyond any refutation.

Obsolete theories

Biology

• Lamarckism—although revitalized as neolamarckism—see also epigenetic heritage
• Myasmatic Theory of Disease—Supplied by Microbial Theory of Disease
• Spontaneous generation (Archebiosis)
• Theory of recapitulation — or "the ontogenia recapituates the phylogenia"

Chemistry

• Caloreal theory
• Theory of the Flogisto — replaced by the works of Lavoisier on oxidation
• Cyclol hypothesis.

Physics

• Theoria aristotelian of gravity — discredited by Galileo, who was then supplanted by Newton and eventually supplanted by Einstein again.
• Theory of the gravitation of Le Sage
• Éter — could not be detected by Michelson and Morley’s experiment; obsolete after Einstein’s work
• Atomic model of Thomson's plum puding that assumed protons and electrons were mixed together in a single mass, was discredited by Rutherford's experiment.
• Traditional coloring model based on the existence of three primary colors (red, yellow and blue), which has been moved by the CMYK (sustrative) and RGB (additional).

Astronomy and cosmology

• Ptolemaic/Geocentric universo — obsolete after Copernicus and Galileo
• Copernican Theory/Heliocentric Unit — obsolete after Johannes Kepler and Isaac Newton

Geography

• Flat Earth Theory
• The open polar sea, an ice-free sea that once was supposed to surround the north pole

Geology

• Plate tectonic replaced:
  • Theory of the expanding Earth, or of the growing Earth (substituted by subduction)
  • Geosinclinal theory
  • The continental drift theory was incorporated and improved by plate tectonics
• Catastrophism was replaced by uniformism largely
• Neptunism replaced by plutonism

Medicine

• Theory of the four bodily humors
• Brain lobotomy
• Eclecticism (medicine) — medical history.

Approximate theories

They are theories that are no longer considered the most complete representation of reality, but are still useful in specific domains. For many theories a more complete model is known, but in practice using a coarser approximation gives good results with much less effort.

• Stationary State — The Big Bang and the Dark Matter threaten to destroy this quiet world view
• Atoms are no longer thought to be indivisible: they are currently seen as compounds.
• The atomic nuclei decay to high energies.
• Heliocentric Theory — Used even in the coordinate system of the celestial mechanics.
• Newtonian Mechanics — Obsolete after the theory of relativity and quantum mechanics, remains useful in engineering and physics at medium scales (human) or when it is not necessary to consider significant fractions of the speed of light.
• Bohr atomic model — It is an exact solution of the hydrogen atom, but it does not describe larger atoms well.
• Newton Square Sin Law for Fluid Force on a Body — It is not considered useful at low speeds, although it has found applications in hypersonic flow.

Theories whose importance was overestimated

• Land Languages—Although temporary connections between earth masses sometimes made migrations possible (such as when the sea level dropped during glaciers), the real division of continents caused by plate tectonics has been more important.