Give two evidences to show that the universe is expanding.The two evidences to show that the universe is expanding are red shift and big bang theory Redshift: According to Doppler effect, if the source of light is moving with respect to an observer, there is a change in wavelength of li...

Give two evidences to show that the universe is expanding.

The two evidences to show that the universe is expanding are red shift and big bang theory

 Redshift: According to Doppler effect, if the source of light is moving with respect to an observer, there is a change in wavelength of light received by the observer. This change in wavelength of light is called Doppler effect. If the source of light is moving away from the observer, the observed wavelength of the spectrum shifts towards red and such shift in wavelength is called red shift Experimentally, the red shift is observed in the spectra of galaxies which prove that universe is every  expanding.

 Big Bang Theory: According to Big Bang theories millions of year ago, the whole universe was in the form of highly compressed matter concentrated in the form of huge compact mass of fire-ball. The density and temperature of ball was very high. At a time, the ball was exploded and the matter thrown out in the form of galaxies which are even moving away and away and the universe is ever-expanding as indicated by Hubble's constant