Final answer:
The Big Bang theory explains Olbers's paradox by considering the universe's finite age and expansion, leading to the night sky's darkness due to redshift and finite stellar lifetimes. The abundance of helium is accounted for by Big Bang nucleosynthesis, and the CMBR's wrinkles reflect early quantum fluctuations and gravity's effects, with smaller temperature variations than expected.
Step-by-step explanation:
The Big Bang theory helps resolve Olbers's paradox, which questions why the night sky is dark if the universe is infinite and every line of sight should fall on a star.
Commonly accepted evolution of the universe as a solution to this paradox points out that the universe is not infinitely old; it has a finite age of approximately 13.8 billion years. Therefore, only the light from stars within our observable universe, the spherical region of the universe from which light has had time to reach us since the Big Bang, has had enough time to reach Earth. Additionally, due to the universe's ongoing expansion, distant stars are moving away from us, causing their light to redshift, which means that the wavelength elongates, making the radiation less visible and contributing to the darkness of the night sky. Moreover, many stars have finite lifespans and will not emit light indefinitely; they eventually burn out and die, removing their light from the observable universe.
In terms of helium abundance, the Big Bang scenario solves the problem by suggesting that helium was one of the first elements to be formed in the early stages of the universe, during a period known as Big Bang nucleosynthesis. This theory predicts that a significant amount of helium was created in the first few minutes after the Big Bang, which aligns with the observed abundance of helium today.
Finally, when looking back at the time of the Big Bang, rather than seeing an explosion, we observe the cosmic microwave background radiation (CMBR) as the farthest observable relic of the early universe. The CMBR shows slight fluctuations in temperature, known as wrinkles, caused by quantum fluctuations during the inflationary phase of the universe and the subsequent growth of these fluctuations under the influence of gravity. The temperature variations observed in the CMBR are less than originally expected, pointing towards an early universe that was remarkably uniform with only slight differences in density.