SUPERSEDED SCIENTIFIC THEORIES

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The obsolete Geocentric model of the universe places the Earth at the centre.
A 'superseded', or 'obsolete, scientific theory' is a scientific theory that was once commonly accepted but (for whatever reason) is no longer considered the most complete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.

Contents
Superseded biology theories
Superseded chemistry theories
Superseded physics theories
Superseded astronomical and cosmological theories
Superseded geographical and climatological theories
Superseded geological theories
Superseded medical theories
Obsolete branches of enquiry
Approximate theories
See also
Lists

Superseded biology theories


Giraffes are often invoked in explanations of Lamarck's superseded theory of evolution. In Lamarckism, a giraffe is able to lengthen its neck over its life time, for example by stretching to reach higher leaves, and subsequently have an offspring with a longer neck. The theory has been superseded by the understanding of natural selection as the primary mechanism of evolution.


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 (commonly occurring abiogenesis) superseded by "Omne vivum ex ovo" (life comes from life)

Recapitulation theory - or "ontogeny recapitulates phylogeny"

Superseded chemistry theories



Caloric theory

Phlogiston theory - replaced by Lavoisier's work on oxidation

★ Part of Dalton's law

Vital essence theory

Superseded physics theories



Aristotelian theory of gravity - discredited by Galileo

Ether - 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

Emitter theory - another now-obsolete theory of light propagation.

Persistence of vision - is being debated by investigative psychologists.

★ Progression of atomic theory
:
Plum pudding model of the atom - assuming the protons and electrons were mixed together in a single mass
:
Rutherford solar system model of the atom with an impenetrable nucleus orbitted by electrons.
:
Bohr model with quantized orbits
:
Electron cloud model following the invention of Quantum Mechanics in 1925 and the eventual atomic orbital models derived from the quantum mechanical solution to the hydrogen atom.

Superseded astronomical and cosmological theories



Ptolemaic system/Geocentric universe - obsoleted by Copernicus and Galileo

Copernican system - obsoleted by Johannes Kepler and Isaac Newton

Newtonian gravity - obsoleted by general relativity

Superseded geographical and climatological theories



Flat Earth theory

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)

Superseded geological theories



Continental drift was superseded by plate tectonics

Expanding earth theory replaced by a ''statist'' model with Subduction

Catastrophism was replaced by Uniformitarianism

Superseded medical theories



★ Theory of the four bodily humours

Eclecticism (medicine) - medical history - Some say it transformed into homeopathy and pseudoscience.

Physiognomy, related to phrenology, was the study of one's physical appearance in relation to one's inner character.

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

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.

Classical electrodynamics - approximation to quantum electrodynamics

Bohr model of the atom - extended by the quantum mechanical model of the atom.

★ 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

See also



Science

Philosophy of science

Scientific theory

Falsifiability - Karl Popper

Paradigm shift

Creation-evolution controversy
Lists


List of pseudoscientific theories

List of minority-opinion scientific theories

List of discredited substances

List of famous discoveries

List of famous experiments

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