Why Did the Formation of Particle-Antiparticle Pairs (Such as Protons

question 23

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.

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Definitions:

Aerobic Fitness

The ability of the heart, lungs, and circulatory system to supply oxygen efficiently during sustained physical activity.

Heart Attack

A medical emergency where the blood flow to the heart is suddenly blocked, resulting in damage to the heart muscle.

Cardiorespiratory Fitness

A health-related component of physical fitness that relates to the ability of the circulatory and respiratory systems to supply oxygen during sustained physical activity.

Anaerobic Exercise

High-intensity physical activity that does not rely on oxygen as the primary energy source and focuses on strengthening muscles.