How do changes in light wavelengths support the most widely accepted ideas about the universe?

Changes in light wavelengths, observed through phenomena like redshift and blueshift, provide critical evidence for the expansion of the universe and the Big Bang theory. As galaxies move away, the light they emit shifts to longer wavelengths, indicating that the universe is expanding. This supports the idea that the universe originated from a hot, dense state and has been expanding ever since. Additionally, the study of cosmic microwave background radiation, which has a specific wavelength, offers insights into the early conditions of the universe, further solidifying these foundational theories.