Redshift

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The redshift of a given object is a measure of the amount that the wavelength of its emitted or reflected electromagnetic radiation has increased. This increase in wavelength is due to the relative motion of a source with respect to an observer; a light emitting source moving away from an observer will have its spectrum shifted toward longer (in optical light, redder) wavelengths. In practice this is analogous to the Doppler shifting of sound waves emitted from a moving source. Light emitted from a source moving towards an observer will experience a blueshift. In the case of redshift, however, most of the redshift is believed to be due not to the object moving through space, but to the expansion of space itself.

Support for the Big Bang theory

The Hubble redshift in atomic spectra of distance cosmic objects, discovered by Edwin Hubble around 1929, is claimed as a source of evidence for the Big Bang theory.[1] The redshift, the expanded wavelength of light, suggests that these objects are moving away from Earth due to the expansion of the universe. It also suggests either that the universe is undergoing accelerating expansion for an unknown reason, or that there exists Hubble time dilation causing such an effect in stationary Einstein's universe. The latter effect is expected by observational predictions of Einsteinian gravitation. It also complies with the perfect cosmological principle. This is a phenomenon predicted by the Big Bang theory. However, creationist cosmologies also predict this expansion, so the evidence cannot be used in support of the Big Bang theory over creationist theories.

References

  1. Edwin Hubble (1929). "A relation between distance and radial velocity among extra-galactic nebulae". Proceedings of the National Academy of Sciences 15: 168–173.