Question

there is a theory that gravity could pull galaxies back together, causing a reverse big bang
which observation makes this theory less likely than the idea that the universe may continue to expand?

• background radiation is present.
• galaxies exist outside of the milky way.
• the expansion of the universe is accelerating.
• gas giants form farther from the sun, where temperatures are cooler

Explanation:

To determine which observation makes the "reverse big bang" theory less likely, we analyze each option:

• "Background radiation is present" supports the Big Bang theory but doesn't directly relate to the expansion vs. contraction of the universe.
• "Galaxies exist outside of the Milky Way" is about the existence of other galaxies, not about the expansion or contraction of the universe.
• "The expansion of the universe is accelerating" means the universe is not slowing down due to gravity (which would be needed for a reverse big bang) but instead speeding up, making the reverse big bang theory less likely.
• "Gas giants form farther from the Sun..." is about solar system formation, not the universe's expansion/contraction.

Answer:

C. The expansion of the universe is accelerating