Question

The scientific explanation that suggests the universe is expanding relies on two main concepts _____.

A. the Doppler effect and redshift
B. redshift and blueshift
C. redshift and gravitational pull
D. Doppler effect and quasars

Answer 1

The scientific explanation regarding the expansion of the universe is narrowed down to two main concepts: the Doppler effect and redshift. The light coming from stars from the distance can be shifted in the same way as a pitch of sound does.

Hope my answer has helped you.

Answer 2

Answer;

A. the Doppler effect and redshift

Explanation;

• Hubble used the Doppler effect to establish that the universe was expanding. Such that the light from distant galaxies was shifted towards the lower frequencies, to the red end of the spectrum. This is called the red Dopller shift or the Red-shift.
• Red-shift was an observation by Edwin Hubble in 1925. Hubble observed that the red shift of galaxies was directly proportional to the distance of the galaxy from earth, which means, things farther away from Earth were moving away faster and therefore, the universe must be expanding.