Ether can be defined from the point of view of Physics, Chemistry and Philosophy. In the first and last fields it has been very controversial to agree on a single definition. Sources define it in the following ways:
- Hypothetical material medium that fills the space. This subtle and invisible fluid was the support of physical waves. The concept of ether was already accepted by the philosophers of classical antiquity, who considered the ether as a certain “primary matter” and identified it with space.
- In classical physics, ether was understood as the homogeneous, mechanical, and elastic medium that filled the absolute Newtonian space. This metaphysicalconception did not withstand experimental testing and was discarded in the theory of relativity .
- In current physics, the notion of ether has been replaced by the representation of a material field, irreducible to a mechanical medium. The doctrine of the field has preserved the rational nucleus of the hypothesis concerning the ether, the idea that it is impossible for absolutely empty space to exist, the idea that space is inseparable from matter.
- From the chemical point of view, any of the organic, volatile and soluble compounds, which have an oxygen atom attached to two hydrocarbon radicals, such as diethyl, is used as an anesthetic: ethyl oxide, a highly volatile liquid. and flammable, with a very strong odor, also called sulfuric ether ( Ethyl ether).
- Some sources use it as a complement in the definitions of ethereal, essence, sky, celestial spaces, celestial vault, etc.