Final answer:
Olbers's paradox, which asks why the sky is dark at night if the universe is infinite and filled with stars, is explained by the finite age and expansion of the universe. The cosmic microwave background radiation's temperature variations are due to quantum fluctuations and gravitational interactions in the early universe, and they were less than originally expected.
Step-by-step explanation:
The question asked in Olbers's paradox of cosmology is: Why is the sky dark at night? This paradox stems from the idea that if the universe is infinite and contains an infinite number of stars, then every line of sight should eventually fall upon the surface of a star, making the night sky bright. The explanation lies in the commonly accepted evolution of the universe. The Big Bang theory suggests the universe has a finite age and is expanding. Due to the finite speed of light and the vast distances in the universe, we cannot see light from all the stars. Some of them have not had enough time for their light to reach us. Additionally, the expansion of the universe causes the light from distant stars to be redshifted and diminished in brightness.
The cosmological solution to Olbers's paradox invokes the expansion and age of the universe, leading us to observe a night sky that is predominantly dark.
The CMBR is the thermal remnant of the Big Bang and exhibits hot and cold regions, known as 'wrinkles'. These temperature variations can be attributed to quantum fluctuations in the early universe that were magnified during cosmic inflation. They can also result from the distribution of matter affecting the photon-baryon fluid through gravitational interactions. The observed temperature fluctuations in the CMBR are less than initially expected, indicating a high degree of isotropy and homogeneity in the early universe.