Doppler Effect in Relativity

The Doppler Effect in relativity describes how the frequency of light or sound changes due to the relative motion between the source and the observer. When the source moves toward the observer, the waves are compressed, resulting in a higher frequency (blue shift). Conversely, when it moves away, the waves stretch, causing a lower frequency (red shift). In special relativity, this effect is enhanced due to the finite speed of light and time dilation, meaning time can pass differently for observers in motion. This leads to significant implications in astrophysics and our understanding of the expanding universe.