Scientists have observed that the light emitted from faraway galaxies is shifted toward the red on the electromagnetic spectrum
compared to similar galaxies that are closer. This is called a redshift. How does this data support the idea that the universe began with a period of rapid expansion and is continuing to expand?
According to the Big Bang theory, the universe is actually expanding continuously, that the clusters of the galaxies has been more distanced in between of this. And this is where the red shift enters. The red shift is a phenomenon, in which described as the movements of the galaxies.
During the formulation of the theory called "redshift" it was found that some spiral nebulae, when moving away from the earth, established a red shift.
By observing the redshift, the scientists were able to perceive that the nebulae were axially distant, that is, the Doppler effect occurred, where enlargement or reduction of the frequency of a wave could be observed in reference to the nebula in motion. From that, it was possible to conclude that the redshift is caused by the recession movement of the nebulae. Which may indicate that the universe is expanding continuously.
