Why was the luminiferous ether abandoned after Einstein’s theory of relativity?

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Brian Greene sits in a living room, holding a pen, with handwritten equations m = E/c^2 and E = mc^2 on a whiteboard beside him, highlighting c^2 as the speed of light. — relativity Brian Greene kicking off his *Your Daily Equation* video series with Albert Einstein's famous equation E = mc².

The luminiferous ether was a hypothetical, undetectable medium once believed to be necessary for the transmission of electromagnetic waves through space. Its existence was seriously challenged by the Michelson-Morley experiment, which failed to detect any evidence of Earth’s motion through such a medium.123

The hypothesis was ultimately abandoned following the formulation of special relativity by Albert Einstein in 1905. Einstein postulated that the speed of light is a universal constant for all observers, regardless of their relative motion. Because this postulate rendered the concept of a preferred reference frame—which the ether was intended to provide—entirely unnecessary, the ether was discarded as an obsolete construct in modern physics.124