aether

Examples of aether in the following topics:

• Back to Maxwell's Equations

  • Maxwell's and his contemporaries spoke of light traveling through some medium known as the aether.
  • Michelson and Morley attempted to measure the motion of the Earth through the aether, but failed.
  • Lorentz proposed that to understand the null result of the experiment objects moving through the aether contract by γ−1 = $\sqrt{1-v^2/c^2}$where γ is the Lorentz factor.
  • Einstein's insight was that if the speed of light was the same for everyone moving uniformly, one would get the apparent "Lorentz" contraction without needing the aether through which light propagates or for the aether to contract objects.
  • The aether was originally proposed by Aristotle and experiments agreed with it for about 2,200 years, so throwing it away was a big deal.

• Length Contraction

  • Let's look at the results with the aether again.If we have a rod of length $L_0$ in the primed frame what it is length in the unprimed frame.

• The Michelson Interferometer

  • The best known application of the Michelson Interferometer is the Michelson-Morley experiment—a failed attempt to demonstrate the effect of the hypothetical "aether wind" on the speed of light.
  • Their experiment left theories of light based on the existence of a luminiferous aether without experimental support, and served ultimately as an inspiration for special relativity.

• Einstein's Postulates

  • Physicists assumed that there exists a stationary medium for the propagation of light, which they called "luminiferous aether. " In 1887, Michelson and Morley attempted to detect the relative motion of the Earth through the stationary luminiferous aether, but their negative results implied the speed of light c is independent of the motion of the source relative to the observer.

• Simultaneity

  • However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable frame of reference, and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers.
  • In 1905, Albert Einstein abandoned the (classical) aether and emphasized the significance of relativity of simultaneity to our understanding of space and time.

• The Speed of Light

  • This invariance of the speed of light was postulated by Einstein in 1905 after being motivated by Maxwell's theory of electromagnetism and the lack of evidence for "luminiferous aether"; it has since been consistently confirmed by many experiments.