Final answer:
The wavelength of light stretches due to cosmological redshift as it travels through the expanding space over many years, with light from more distant galaxies displaying greater redshift compared to closer ones.
Step-by-step explanation:
As light travels through space over many years, a phenomenon known as cosmological redshift occurs. This effect is caused by the expansion of space itself, which stretches the wavelength of photons in transit. The greater the distance the light has to cover, the more stretched the wavelength becomes, effectively increasing the 'redness' or redshift of the light. Due to this stretching of space and the associated wavelengths, light from more distant galaxies displays a greater redshift when compared to closer ones.
The propagation of light weakens as it covers a larger area, following the inverse square law, but this diminishment of intensity is distinct from the change in wavelength caused by the cosmic expansion. The cosmological redshift is a key aspect of cosmology, aiding astronomers in understanding the universe's evolution by observing light that has been stretched over astronomical distances and time scales.