Astrophysics: Red-Shift

Red-shift is a concept in Astrophysics which refers to the displacement of spectral lines towards longer wavelengths, often in the light from distant galaxies.
The phenomenon of Red-shift is associated with the Doppler Effect. When a light source moves away from the observer, the observed wavelength is longer (i.e., ‘shifted’ towards the red end of the spectrum).
Edwin Hubble, an American astronomer, found out that galaxies are moving away from us, and the further away they are, the faster they’re moving. This provided strong proof for the theory of an expanding universe.
Understanding Red-shift is fundamental for considering the Big Bang Theory - this theory suggests that the universe began from a very high-density state and then expanded. The Red-shift effect presents evidence for this expansion.
The discovery of cosmic microwave background radiation also supported the Big Bang Theory. This radiation is the heat left over from the Big Bang, cooled to just 2.7 degrees above absolute zero.
The greater the red-shift, the further away the light source is from us and the faster it is moving away from us.
However, not all Red-shift is due to the Doppler Effect and galaxy motion. A type called ‘Cosmological Red-shift’ is due to the expansion of the universe itself.
Measuring the Red-shift can provide information about the distance of galaxies and the rate of expansion of the universe.
Understanding Red-shift is vital in the field of Astrophysics for interpreting the light that we receive from distant sources and for understanding the overall structure and history of the universe.
It’s important to also know about Blue-shift, the opposite effect, in which the object is moving towards the observer, and the light is ‘shifted’ to the blue part of the spectrum.