Superseded scientific theories

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A superseded, or obsolete, scientific theory is a scientific theory that mainstream scientific consensus once commonly accepted but now no longer considers the most complete description of reality, or simply false. This label does not cover protoscientific or fringe science theories with limited support in the scientific community. Also, it does not mean theories that were never widely accepted. Some theories that were only supported under specific political authorities, such as Lysenkoism, may also be described as obsolete or superseded.

In some cases a theory or idea is found baseless and is simply discarded. For example, the phlogiston theory was entirely replaced by the quite different concept of energy and related laws. In other cases an existing theory is replaced by a new theory that retains significant elements of the earlier theory; in these cases, the older theory is often still useful for many purposes, and may be more easily understood than the complete theory and lead to simpler calculations. An example of this is the use of Newtonian physics, which differs from the currently accepted relativistic physics by a factor that is negligibly small at velocities much lower than that of light. All of Newtonian physics is so satisfactory for most purposes that it is more widely used except at velocities that are a significant fraction of the speed of light, and simpler Newtonian but not relativistic mechanics is usually taught in schools. Another case is the theory that the earth is approximately flat; while it has for centuries been known to be wrong for long distances, considering part of the earth's surface as flat is usually sufficient for many maps covering areas that are not extremely large, and surveying.

The obsolete Geocentric model of the universe places the Earth at the centre.

Superseded theories[edit]

Biology[edit]

Chemistry[edit]

  • Caloric theory - the theory that a self-repelling fluid called "caloric" was the substance of heat. Rendered obsolete by the mechanical theory of heat.
  • Classical elements - All matter was once thought to be composed of various combinations of classical elements (most famously air, earth, fire, and water). This was finally refuted by Antoine Lavoisier's publication of Elements of Chemistry, which contained the first modern list of chemical elements, in 1789.
  • Phlogiston theory – The theory that combustible goods contain a substance called "phlogiston" which entered air upon combustion. Replaced by Lavoisier's work on oxidation
  • Points two and three of Dalton's Atomic Theory
  • Vitalism - See section on biology.

Physics[edit]

  • Democritus, the originator of atomic theory, held that everything is composed of atoms, which are indestructible
  • John Dalton's model of the atom, which held that atoms are indivisible and indestructible (superseded by nuclear physics) and that all atoms of a given element are identical in mass (superseded by discovery of atomic isotopes).[1]
  • Plum pudding model of the atom—assuming the protons and electrons were mixed together in a single mass
  • Rutherford model of the atom with an impenetrable nucleus orbited by electrons
  • Bohr model with quantized orbits
  • Electron cloud model following the development of quantum mechanics in 1925 and the eventual atomic orbital models derived from the quantum mechanical solution to the hydrogen atom

Astronomy and cosmology[edit]

Geography and climate[edit]

  • Flat Earth theory. On length scales much smaller than the radius of the Earth, a flat map projection gives a quite accurate and practically useful approximation to true distances and sizes, but departures from flatness become increasingly significant over larger distances.
  • Terra Australis
  • Hollow Earth theory
  • The Open Polar Sea, an ice-free sea once supposed to surround the North Pole
  • Rain follows the plow – the theory that human settlement increases rainfall in arid regions (only true to the extent that crop fields evapotranspirate more than barren wilderness)
  • Island of California – the theory that California was not part of mainland North America but rather a large island

Geology[edit]

Psychology[edit]

Medicine[edit]

Obsolete branches of enquiry[edit]

Theories now considered incomplete[edit]

Here are theories that are no longer considered the most complete representation of reality, but are still useful in particular domains or under certain conditions. For some theories a more complete model is known, but in practical use the coarser approximation provides good results with much less calculation.

See also[edit]

Lists

References[edit]

  1. ^ De Leon, Professor N. "Dalton's Atomic Theory". Chemistry 101 Class Notes. Indiana University Northwest. Retrieved 26 August 2013. 
  2. ^ Crain, Stephen and Diane C. Lillo-Martin (1999). An Introduction to Linguistic Theory and Language Acquisition. Oxford: Blackwell. 
  3. ^ Aerodynamics: Selected Topics in the Light of Their Historical Development,book by Theodore Von Karman, 1954, Dover Publications, p10 and following pages Detailed discussion of Newton's sine-square law, invalidity in the general case and applicability at high supersonic speeds.