Obsolete scientific theory

A superseded, or obsolete, scientific theory is a scientific theory that was once widely accepted within the mainstream scientific community but is no longer considered to be an adequate or complete description of reality, or is considered to be 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that were only supported under specific political authorities, such as Lysenkoism, may also be described as obsolete or superseded. 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.

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.

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.

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