What is the cosmological red shift? I've seen it before and couldn't figure out what exactly it was. All I know is that it has something to do with the effects of gravity and how it relates to photon frequency.
The theory of general relativity holds that light moving through strong gravitational fields experiences a red- or blueshift. This is known as the Einstein shift. The effect is very small but measurable on Earth using the Mossbauer effect. However it is significant near a black hole and as an object approaches the event horizon, the red shift becomes infinite. It is also the dominant cause of large angular scale temperature fluctuations in the cosmic microwave background radiation. Gravitational redshift was offered as an explanation of the redshift of quasars in the 1960s, although this is not widely accepted now.
AFAIK, the term "redshift" originated in spectroscopy. In early (and many modern) spectroscopes, the light from an object first passed through a slit, and was then dispersed; a single frequency (wavelength) thus appeared as a 'line' in the resulting spectrum. Atomic spectra are full of discrete lines, corresponding to the electronic transitions in excited atoms or ions. If the source of the light is in motion wrt the spectroscope, with a component towards or away from it, a particular atomic line will be seen at a different frequency/wavelength - if the source is moving towards the spectroscope, the line will appear at a higher frequency/shorter wavelength; and if away at a lower frequency/longer wavelength. As red light has a lower frequency than blue, the 'shifts' caused by relative radial motion came to be called blueshift and redshift.lvlastermind said:What is the cosmological red shift? I've seen it before and couldn't figure out what exactly it was. All I know is that it has something to do with the effects of gravity and how it relates to photon frequency.