, or obsolete, scientific theory
is a scientific theory
that was once commonly accepted, but that is no longer considered the most complete description of reality by a mainstream scientific consensus
; or a falsifiable
theory which has been shown to be false. This label does not cover protoscientific
or fringe science
theories with limited support in the scientific community
, nor does it describe theories that were never widely accepted. Some theories which were only supported under specific political authorities, like Lysenkoism
, may also be described as obsolete or superseded.
In some cases, a theory or idea is found to be 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 which retains elements of the earlier theory; in these cases, the older theory is often still useful because it provides a description that is "good enough" for many purposes, is more easily understood than the complete theory, and may 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 which is negligibly small at velocities much lower than that of light. Newtonian physics is so satisfactory for most purposes that many secondary educational systems teach it, but not the "correct" relativity. Another case is the theory that the earth is approximately flat; while clearly wrong for long distances, it was originally a profound insight by primitive people who lived in a landscape with hills, rivers, and valleys; viewing a landscape as flat it is still sufficient for most local maps and surveying.
Karl Popper suggested that a theory should be considered scientific if and only if it can in principle be falsified by experiment; any idea not susceptible to falsification does not belong to science.
Superseded biology theories
Superseded chemistry theories
Superseded physics theories
- *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 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Superseded astronomical and cosmological theories
Superseded geographical and climatological theories
- Flat Earth theory. On length scales much smaller than the radius of the Earth, a flat map projection gives a quite accurate approximation to true distances and sizes, but distortions become increasingly significant over larger distances.
- 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
Superseded economic theories
Superseded psychological theories
Superseded medical theories
Obsolete branches of enquiry
Theories now considered to be approximations
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.