* Redshift and the Doppler Effect: Redshift is the phenomenon where light from distant objects appears shifted towards the red end of the electromagnetic spectrum. This is analogous to the Doppler effect we experience with sound waves, where a moving object's sound appears higher in pitch (blueshift) as it approaches and lower in pitch (redshift) as it moves away.
* Cosmological Redshift: The redshift observed in galaxies is not due to their motion through space, but rather to the expansion of space itself. As the universe expands, the space between galaxies stretches, and the wavelengths of light emitted by those galaxies are stretched along with it. This stretching causes the light to shift towards the red end of the spectrum.
* Hubble's Law: Edwin Hubble's observations in the 1920s showed a direct correlation between the redshift of galaxies and their distance from Earth. This relationship, known as Hubble's Law, provides strong evidence for the expanding universe.
In summary: The redshift of galaxies provides compelling evidence that the universe is expanding. This discovery revolutionized our understanding of the universe and its origins.
