Historically, science incorporated various aether theories to explain the transmission medium.

These theories were developed from the 16th until the 19th century in connection with the aether theories.

Hence these theories resemble the 19th century aether theories in name only.

The assorted aether theories embody the various conceptions of this "medium" and "substance".

They emphasize that the negative results of those tests are also consistent with aether theories in which moving bodies are subject to time dilation.

Aethyr is a concept of a formless and invisible medium or substance that pervades the cosmos - compare & contrast with Aether theories.

With the 18th century physics developments some physical models known as "aether theories" made use of a similar concept as an explanation for the propagation of electromagnetic or gravitational forces.

These aether theories are considered to be scientifically obsolete, as the development of special relativity showed that Maxwell's equations do not require the aether for the transmission of these forces.

In order for these results to be consistent with an aether, it had to be assumed that the aether was dragged along with the earth to a much greater extent than aether theories typically predicted.

In addition, the various number of aether theories in classical physics which supposed a "fifth element", such as the Luminiferous aether, was nullified by the Michelson-Morley experiment in an attempt to detect the motion of earth through the aether.

What is now often called Lorentz Ether theory ("LET") has its roots in Hendrik Lorentz's "Theory of electrons", which was the final point in the development of the classical aether theories at the end of the 19th and at the beginning of the 20th century.

The majority of modern physicists, in spite of acknowledging the phenomena known as vacuum energy and the existence of other unsolved problems in physics that are unexplained by current standard theories, continue to maintain that there is no need to imagine that a medium for propagation of electromagnetic waves exists (see also aether theories).

In order to explain the Michelson-Morely experiment (1887), which apparently contradicted both Fresnel's and Lorentz's immobile aether theories, and apparently confirmed Stokes' complete aether drag, Lorentz theorized (1892) that objects undergo "length contraction" by a factor of in the direction of their motion through the aether.