Space

Question 1

Reasons for the big bang theory (CMBR)

Answer 1

CMBR is everywhere/ is the same in all directions
Implying that all parts of universe were in contact a long time ago
Wavelength has increased since the universe expanded
Universe was hotter long ago.

Question 2

Reasons for the big bang theory (red shift of galaxies)

Answer 2

Red shift of galaxies
Further the galaxy from earth the greater the red shift
Larger redshift means faster movement of galaxies
Therefore the further away, the faster the galaxy moves
Galaxies moving apart from each other implies expansion from a single point or since the Big Bang