Superseded scientific theories

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Image:Cellarius ptolemaic system c2.jpgA superseded, or obsolete, scientific theory is a scientific theory that was once commonly accepted but (for whatever reason) is no longer considered the most complete description of reality by mainstream science; or a falsifiable theory which has been shown to be false. This label does not cover theories that are yet to gain wide support in the scientific community (protoscience or fringe science). This also does not cover theories that were never widely accepted. Some theories which were only supported under specific political authorities, like Lysenkoism, may also be included.

In some cases, the theory has been completely discarded. In other cases, the theory is still useful because it provides a description that is "good enough" for a particular situation, and is more easily used than the complete theory (often because the complete theory is too mathematically complex to be easily usable). An example of this is the use of Newtonian physics in many mechanical engineering applications, and even in calculating the orbits of satellites, because the deviation from such physics is smaller than other sources of error. Karl Popper suggested that all scientific theories should be falsifiable otherwise they could not be tested by experiment. Anything that cannot be shown by experiment to be false would therefore be an axiom and have an absolute status, beyond any confirmation or refutation.

1 Superseded biology theories
2 Superseded chemistry theories
3 Superseded physics theories
4 Superseded astronomical and cosmological theories
5 Superseded geographical and climatological theories
6 Superseded geological theories
7 Superseded medical theories
8 Obsolete branches of enquiry
9 Approximate theories
10 See also
- 10.1 Lists

[edit] Superseded biology theories

Image:Giraffes, Pengo.jpg

Lamarckism challenged by Darwinian evolution, but revitalised in Neo-Lamarckism - see also epigenetic inheritance
Maternal impression - rendered obsolete by genetic theory, but see fetal origins of adult disease
Miasma theory of disease - rendered obsolete by germ theory of disease
Spontaneous generation (abiogenesis)
Recapitulation theory - or "ontogeny recapitulates phylogeny"

[edit] Superseded chemistry theories

Caloric theory
Phlogiston theory - replaced by Lavoisier's work on oxidation
Part of Dalton's law
Vital essence theory

[edit] Superseded physics theories

Aristotelian theory of gravity - discredited by Galileo
Aether - failed to be detected by the Michelson-Morley experiment, made obsolete by Einstein's work.
Caloric theory - Lavoisier's successor to phlogiston, obsolesced by Rumford's and Joule's work
Plum pudding model of the atom - assuming the protons and electrons were mixed together in a single mass
Emitter theory - another now-obsolete theory of light propagation.
Persistence of vision - is being debated by investigative psychologists

[edit] Superseded astronomical and cosmological theories

Ptolemaic system/Geocentric universe - obsoleted by Copernicus and Galileo
Copernican system - obsoleted by Johannes Kepler and Isaac Newton

[edit] Superseded geographical and climatological theories

Flat 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)

[edit] Superseded geological theories

Continental drift was superseded by plate tectonics
Expanding earth theory replaced by a statist model with Subduction

[edit] Superseded medical theories

Theory of the four bodily humours
Eclecticism (medicine) - medical history - Some say it transformed into homeopathy and pseudoscience.

[edit] Obsolete branches of enquiry

Alchemy, which led to the development of chemistry
Astrology, which led to the development of astronomy
Phrenology, was once widely studied but now considered a pseudoscience
Numerology, as distinct from number theory, now considered a pseudoscience

[edit] Approximate theories

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

Steady State - replaced by an expanding universe model starting with the Big Bang. See also: dark matter.
Atomic theory - Atoms are no longer thought to be indivisible, but are now seen to be composites.
Nuclei disintegrate at high energy.
Heliocentric universe theory - This is still used in the coordinate system of celestial mechanics.
Newtonian mechanics - extended by Theory of Relativity and quantum mechanics. Still useful in engineering and physics at either middling (human) scales or where appreciable fractions of the speed of light need not be considered.
Bohr model of the atom - Allows for exact solution of the hydrogen atom, but larger atoms are not well described.
Newton's sine-square law for the force of a fluid on a body - no longer considered useful at low speeds, though it has found application in hypersonic flow