The spectrum allows us to identify key features, such as the spike-like emission lines of excited hydrogen gas, to determine precisely how much those lines have redshifted
Quasar light is redshifted
, stretched toward the red part of the spectrum, which astronomers now attribute to the expansion of the universe.
Combining (31) and (32), we find that the energy flux of the source of a black body that is redshifted
is of order [(1 + z).sup.4].
Conversely, if the particles become lighter, the frequencies get redshifted
A galaxy's light is redshifted
, or stretched to longer wavelengths, by the expansion of the universe.
Atoms made of young, low mass particles would give off radiation that would be redshifted
compared to the atoms of the same elements on Earth.
Blue stellar objects, such as quasars, are intensely radiating bodies, even if they are redshifted
. Blue stars burn themselves out in relatively short cosmic lifetimes.
If quasars were moving close to the speed of light, associated relativistic effects would make blueshifted quasars easier to detect than redshifted
quasars, but none have ever been found.
In the FLRW universe due to the time dependent scalar factor, light gets redshifted
. According to the theory of GR, light travels on null geodesics (i.e., [ds.sup.2] = 0).
All wavelengths are redshifted
. That means that high-energy gamma rays beyond a detector's energy range would get shifted into the detectable range by cosmic expansion, while slower-energy gamma rays would get shifted to below the detector's range.--R.
Cosmic expansion shifts distant galaxies' light to longer wavelengths, and highly redshifted
galaxies are visible only at infrared wavelengths.
However, we know dozens of much more redshifted
galaxies and quasars.