Question

Choose the statement that best describes why antimatter is very rare today.

A. As the universe expands, antimatter is converted into dark matter, resulting in only a very small amount of antimatter left from the early universe.
B. Antimatter is not a stable form of matter and spontaneously decays into energy and ordinary particles
C. Right after the big bang, there was more ordinary matter than antimatter, when the two types annihilated, only the ordinary matter remained.
D. In order to power fusion in their cores, stars require small amounts of antimatter and have used up the large supply available from the early universe

Answer 1

Antimatter is rare in today's universe due to a slight asymmetry after the Big Bang, where more matter than antimatter led to the survival of matter after mutual annihilation. This leftover matter formed the stars and galaxies, with the lack of annihilation radiation supporting matter's dominance.

Step-by-step explanation:

The statement that best describes why antimatter is very rare today is: C. Right after the big bang, there was more ordinary matter than antimatter, when the two types annihilated, only the ordinary matter remained. During the early universe, there was a tiny asymmetry; for every billion particles of antimatter, there was a billion and one particles of matter. After matter and antimatter annihilated each other, a small amount of matter was left over, which led to the formation of the stars and galaxies we see today. This is supported by the lack of annihilation radiation in the universe and by observations that show most of the universe is dominated by matter.

Particle physics suggests a fundamental small asymmetry in the basic forces, which caused more matter than antimatter to exist in the early universe. Although antimatter is created in particle collisions and certain types of decay, such as β+ decays, it exists only in small amounts that quickly annihilate, leaving almost pure matter surviving.