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By the late nineteenth century, however, a handful of experimental anomalies remained that could not be explained by the simple wave theory.
One of these anomalies involved a controversy over the speed of light.
The speed of light and other EMR predicted by Maxwell's equations did not appear unless the equations were modified in a way first suggested by FitzGerald and Lorentz ( see history of special relativity ), or else otherwise it would depend on the speed of observer relative to the " medium " ( called luminiferous aether ) which supposedly " carried " the electromagnetic wave ( in a manner analogous to the way air carries sound waves ).
Experiments failed to find any observer effect, however.
In 1905, Albert Einstein proposed that space and time appeared to be velocity-changeable entities, not only for light propagation, but all other processes and laws as well.
These changes then automatically accounted for the constancy of the speed of light and all electromagnetic radiation, from the viewpoints of all observers — even those in relative motion.

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