Question

What is the main difference between a cosmological redshift and a Doppler shift?

a) Cosmological redshift is caused by the motion of objects, while Doppler shift is due to the expansion of the universe.

b) Doppler shift is related to the expansion of the universe, while cosmological redshift is caused by the motion of objects.

c) Both cosmological redshift and Doppler shift are caused by the motion of objects.

d) Cosmological redshift is unrelated to the motion of objects, while Doppler shift is solely due to their motion.

Answer 1

The main difference between a cosmological redshift and a Doppler shift is that the cosmological redshift is caused by the expansion of space itself, while the Doppler shift is caused by the motion of objects.

Step-by-step explanation:

The main difference between a cosmological redshift and a Doppler shift is that the cosmological redshift is caused by the expansion of space itself, while the Doppler shift is caused by the motion of objects.

In the case of cosmological redshift, as light travels through expanding space, its wavelength gets stretched, resulting in a redshift. This phenomenon is observed when galaxies that are farther away exhibit progressively greater redshifts

On the other hand, the Doppler shift is related to the motion of objects. When an object moves away from an observer, the wavelength of the emitted light gets stretched, resulting in a redshift. Conversely, when an object moves towards an observer, the wavelength gets compressed, resulting in a blueshift.