Halton Arp: Difference between revisions

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→‎Quasars and redshifts: removed no-longer-working link to "Quasar#redshift controversy"
(→‎Quasars and redshifts: removed no-longer-working link to "Quasar#redshift controversy")
==Quasars and redshifts==
{{main|Quasar|Quasar#Redshift controversy}}
During the 1950s bright radio sources, now known as [[quasar]]s, had been discovered that did not appear to have an optical counterpart. In 1960 one of these sources, [[3C 48]], was found to be associated with what appeared to be a small blue star. When the [[spectrum]] of the star was measured, it contained unidentifiable [[spectral line]]s that defied all attempts at explanation; [[John Gatenby Bolton]]'s suggestion that these were highly [[redshifted]] sources was not widely accepted. In 1963 [[Maarten Schmidt]] found a visible companion to the quasar [[3C 273]]. Using the [[Hale telescope]], Schmidt found the same odd spectra, but was able to demonstrate that it could be explained as the spectrum of hydrogen, shifted by a very large 15.8% If this was due to the physical motion of the "star", it would represent a speed of 47,000&nbsp;km/s, far beyond the speed of any known star and defying an obvious explanation. Schmidt noted that redshift is also associated with the expansion of the universe, as codified in [[Hubble's law]]. If the measured redshift was due to expansion, then the object in question would have to be very far away, and therefore have an extraordinarily high [[luminosity]], equally beyond any object seen to date. This extreme luminosity would also explain the large radio signal. Schmidt concluded quasars are very distant, very luminous objects.<ref name="schmidt1963">{{cite journal