Superseded scientific theory
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A superseded, or obsolete, scientific theory is a scientific theory that was once widely used, but due to emergence of more accurate present theory is no longer as popular as it used to be. 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 may be included (like flat Earth model or Lysenkoism) or may not be included (like the model of a geocentric universe).
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). Example of this is the use of Newtonian physics in many mechanical engineering applications, and even in calculating the orbits of satellites, and the use of Conservation of mass in chemistry; in both cases, the error due to these simplifying assumptions 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.
Superseded biology theories
- Lamarckism - but revitalised in Neo-Lamarckism - see also epigenetic inheritance
- Maternal impression - rendered obsolete by genetic theory
- Miasma theory of disease - rendered obsolete by germ theory of disease
- Spontaneous generation (Aristotelian abiogenesis)
- Recapitulation theory - or "ontogeny recapitulates phylogeny"
- Vitalism - replaced by reductionism and germ theory
Superseded chemistry theories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Superseded physics theories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.
- 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.
- John Dalton's model that atoms are tiny spheres with hooks that allow them to combine. (Note that otherwise Dalton's atomic theory was quite accurate.)
- Plum pudding model of the atom, by J. J. Thomson - assuming the protons and electrons were mixed together in a single mass.
- Ernest Rutherford's model of the atom (electrons can be in any orbit about the nucleus).
- Neils Bohr's model of the atom (was accurate for the hydrogen atom only).
See also: Gravity, Alternative theories
Superseded astronomical and cosmological theories
- Ptolemaic system/Geocentric universe - obsoleted by Copernicus and Galileo
- Copernican system - obsoleted by Johannes Kepler and Isaac Newton
- Steady state theory - superseded by the big bang model
Superseded geographical and climatological theories
- Flat Earth theory
- The Open Polar Sea, an ice-free sea once supposed to surround the North Pole. Note, however, that global warming has left the North Pole itself free of ice in a number of recent years, and is expected to permanently open the Northwest Passage later in the 21st century.
- 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
Superseded medical theories
- Theory of the four bodily humours
- Eclecticism (medicine) - medical history - Some say it transformed into homeopathy and pseudoscience.
Superseded psychological theories
- Persistence of vision - to a fairly good level it is rejected by investigative psychologists.
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.
- Atomic theory - Atoms are no longer thought to be indivisible, but are now seen to be composites.
- Nuclei disintegrate at high energy.
- The Heliocentric Model and Geocentric Model are still used as computational instruments in celestial mechanics.
- Newtonian mechanics - superseded 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
- Flat Earth. Most ordinary people navigating short distances (hundreds of miles/km) assume the Earth is flat (for example, assuming that all north-south streets in an inner city are parallel). This also extends to assumptions such as that after walking 3 miles west and 4 north, it is 5 miles directly back to the starting point — on a round Earth, it is actually very slightly less.
See also
Lists
- List of alternative, speculative and disputed theories
- List of discredited substances
- List of famous discoveries
- List of famous experimentsde:Überholte Theorien
es:Teoría científica obsoleta sv:Förlegad vetenskaplig teori