Multiple Choice
Why did the formation of particle-antiparticle pairs (such as protons and antiprotons) from gamma rays come to an end in the first second after the start of the Big Bang?
A) Expansion of the universe carried the gamma rays too far apart for them to collide and form particle-antiparticle pairs.
B) The gamma-ray energy decreased as the universe expanded.
C) The universe became transparent to radiation, so gamma rays and particles no longer interacted.
D) The formation of particle-antiparticle pairs exhausted the supply of gamma rays, preventing further formation of particle-antiparticle pairs.
Correct Answer:
Verified
Correct Answer:
Verified
Q18: In a primordial, pregalactic gas cloud, what
Q19: Recent results from very bright supernovae in
Q20: Which of these statements is a correct
Q21: What is the "cosmological redshift"?<br>A) stretching of
Q22: Why is the universe expanding?<br>A) The energy
Q24: Astronomers studying the cosmic microwave background have
Q25: When the Big Bang began, all the
Q26: If the early universe had been perfectly
Q27: Because of the travel time of light,
Q28: How was the cosmic microwave background radiation