Final answer:
Red-shift is evidence for the Big Bang theory as it shows that distant galaxies are moving away from us, indicating the expansion of the universe. This observation is a result of the stretching of light wavelengths due to the expansion of space, supporting the concept of universal expansion.
Step-by-step explanation:
Red-shift provides evidence for the Big Bang theory through the observation that distant galaxies exhibit red-shift in their emitted light, which is proportional to their distance from Earth. This phenomenon is observed as a result of the expansion of space itself, not just the movement of galaxies through space. As space expands, the wavelengths of light traveling through it are stretched, causing them to appear redder. The cosmological red-shift is a measure of this effect and is consistent with what is expected from a universe that started with a massive expansion—the Big Bang. The most accurate way to view these redshifts is as a stretching of light waves alongside the stretching of space. The implication is profound: if galaxies exhibit a red-shift in their light that increases with distance, this implies that the universe is expanding
Edwin Hubble's work in the 1920s demonstrated that galaxies outside our own were receding at speeds proportional to their distance, supporting the idea of a universal expansion. This expansion is not localized to certain galaxies but affects the entire universe. Accordingly, all observers, no matter where they are, see distant galaxies moving away from them, without any central point of expansion, as space itself is expanding ubiquitously.