The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by Edwin Hubble in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>Edwin Hubble (1929). [http://www.pnas.org/cgi/reprint/15/3/168/ "A relation between distance and radial velocity among extra-galactic nebulae"]. Proceedings of the National Academy of Sciences 15: 168–173.</ref> 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 that the universe is undergoing accelerating expansion for an unknown reason. | The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by Edwin Hubble in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>Edwin Hubble (1929). [http://www.pnas.org/cgi/reprint/15/3/168/ "A relation between distance and radial velocity among extra-galactic nebulae"]. Proceedings of the National Academy of Sciences 15: 168–173.</ref> 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 that the universe is undergoing accelerating expansion for an unknown reason. |