What does the presence of redshift in distant galaxies indicate?

The presence of redshift in distant galaxies is a crucial observation in astronomy that indicates the universe is expanding. When light from galaxies is redshifted, it means that the wavelengths of the light are stretched, which occurs when an object is moving away from the observer. This phenomenon is consistent with the Doppler effect, where the frequency of waves changes due to the relative motion of the source and the observer.

This redshift is a key piece of evidence for the Big Bang theory and supports the notion that space itself is expanding. As galaxies move away from us, their light is redshifted, and astronomers can use this data to infer the rate at which the universe is expanding. This discovery laid the groundwork for our understanding of the dynamics of the universe on a cosmic scale, leading to a model where not only are galaxies receding from one another, but the fabric of space is continually stretching over time.

The other options do not align with this understanding of redshift. Describing galaxies as moving towards Earth would imply blue shift rather than redshift. Saying the galaxies are stationary contradicts the observations of their redshift, and attributing their motion entirely to dark matter does not directly address the expansion of the universe indicated by redshift. Thus,