The concept of cosmological redshift is a cornerstone of the expanding universe model. Which of the following best distinguishes cosmological redshift from a Doppler redshift?
Question 2
During the early universe, before the epoch of recombination, the universe was opaque to light. What was the primary reason for this opacity?
Question 3
The Cosmic Microwave Background (CMB) radiation is a nearly perfect blackbody spectrum. What does the precise blackbody nature of the CMB primarily indicate about the early universe?
Question 4
Hubble's Law, given by $v = H_0 d$, describes the relationship between a galaxy's recessional velocity ($v$) and its distance ($d$) from us, where $H_0$ is the Hubble constant. If a galaxy is observed to be moving away from Earth at a velocity of $1050 \text{ km/s}$ and the Hubble constant is approximately $70 \text{ km/s/Mpc}$, what is the approximate distance to this galaxy in megaparsecs (Mpc)?
Question 5
The Big Bang Nucleosynthesis (BBN) model successfully predicts the primordial abundance of light elements. Which of the following scenarios would significantly alter the predicted ratio of hydrogen to helium, and why?
