What Is the "Particle Horizon

question 196

Multiple Choice

What is the "particle horizon"?

• A) The particle horizon is the distance beyond which astronomers cannot see because light cannot have traveled any farther in the finite age of the universe.
• B) The particle horizon is the distance beyond which astronomers cannot see because no stars or galaxies had yet formed at those distances (because astronomers see back in time as they look out into space).
• C) The particle horizon is the distance beyond which signals from Earth radio and television signals cannot have traveled through the universe.
• D) The particle horizon is the distance beyond which astronomers cannot see because of absorbing matter in the universe.

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Definitions:

Genetic Variation

The diversity in gene frequencies, which can influence differences within species' physical appearance, behavior, and susceptibility to diseases.

Population

A group of individuals of the same species living and interbreeding within a given area.

Neutral Alleles

Genetic variants that do not affect the fitness of an organism and are unaffected by natural selection.

Population Size

The total number of individual organisms inhabiting a particular area or environment at a given time.