Here's a simplified explanation:
1. Expansion of Space: The universe is expanding, meaning the space between galaxies is constantly increasing. This expansion stretches the fabric of space itself.
2. Stretching of Wavelengths: As light travels through this expanding space, its wavelengths get stretched. This stretching causes the light to shift towards longer wavelengths, which are perceived as redder colors in the visible spectrum.
3. The Doppler Effect: While not the primary cause of redshift, the Doppler effect also plays a role. The Doppler effect explains why the pitch of a siren changes as it moves towards or away from you. In the case of galaxies, the expansion of space causes them to move away from each other, which also contributes to the redshift of light.
In summary:
* The expansion of space stretches the wavelengths of light emitted from distant galaxies, causing them to redshift.
* The Doppler effect also contributes to redshift due to the galaxies' movement away from each other.
Important Note: The farther a galaxy is from us, the more its light is redshifted. This relationship is a key piece of evidence for the Big Bang theory.
