Changes

| quote = In the early years of the nineteenth century, the English polymath Thomas Young demonstrated that light behaves like a wave. ...Light, they argued, is both like a wave and like a particle, and what is more, it is like wave and like a particle on the level of individual photons themselves.}}</ref>  The ''luminiferous aether'' (or '''''ether''''') is defined to be whatever medium transmits the light waves.

| quote = In the early years of the nineteenth century, the English polymath Thomas Young demonstrated that light behaves like a wave. ...Light, they argued, is both like a wave and like a particle, and what is more, it is like wave and like a particle on the level of individual photons themselves.}}</ref>  The ''luminiferous aether'' (or '''''ether''''') is defined to be whatever medium transmits the light waves.

The [[Michelson-Morley experiment]] in 1887 failed to detect any motion of the Earth relative to the aether. [[Henri Poincaré]] conjectured that the aether may be unobservable, and invented special [[relativity]] based on the notion that the aether may be superfluous. [[Albert Einstein]] published conflicting opinions on whether the aether exists. According to R.Humphreys Einstein’s theories of special and general relativity not only stem from Maxwell’s work which required existence of ether as one of its postulates, but at bottom they only make sense if space (and time) is some kind of “stuff”. Humphreys portrays Einstein as recanting in 1920 his 1905 denial of the 19th-century idea of an “ether” meant to propagate light waves.<ref name="Humphreys"/>  

The [[Michelson-Morley experiment]] in 1887 failed to detect any motion of the Earth relative to the aether. [[Henri Poincaré]] conjectured that the aether may be unobservable, and invented special [[relativity]] based on the notion that the aether may be superfluous. [[Albert Einstein]] published conflicting opinions on whether the aether exists. According to R.Humphreys Einstein’s theories of special and general relativity not only stem from Maxwell’s work which required existence of ether as one of its postulates, but at bottom they only make sense if space (and time) is some kind of “stuff”. Humphreys portrays Einstein as recanting in 1920 his 1905 denial of the 19th century idea of an “ether” meant to propagate light waves.<ref name="Humphreys"/>  

[[Quantum electrodynamics]] (QED) teaches that when light goes through a [[vacuum]], it is really going through a sea of virtual particles. Cosmologists say that the vacuum is really filled with ''dark energy'', and it is unknown whether that has any relation to the aether concept. According to these theories, there is no such thing as empty space. The aether describes space when it is as empty as possible.  

[[Quantum electrodynamics]] (QED) teaches that when light goes through a [[vacuum]], it is really going through a sea of virtual particles. Cosmologists say that the vacuum is really filled with ''dark energy'', and it is unknown whether that has any relation to the aether concept. According to these theories, there is no such thing as empty space. The aether describes space when it is as empty as possible.