Question

is the following statement true or false:
\galaxy mergers occurred less frequently in the past because galaxies were further apart from each other since spacetime has been gradually shrinking over time.\
true
false
question 22 1 pts
if astronomers discovered that the hubble constant was actually half of its current calculated value, then how would that affect their estimate of the age of the universe?
the universe would be twice as old after the recalculation.
the universe would be the same age after the recalculation.
the universe would be half as old after the recalculation.
the universe would be four times older after the recalculation.
the universe would be one - fourth as old after the recalculation.
question 23 1 pts
before the era of recombination, the universe is described as being \opaque\. what does this mean?
photons underwent pair production, and these particles underwent annihilation, at such a high rate to prevent the universe from being transparent.
the high amount of dust during this time absorbed light from the first generation of stars.
the core temperature of stars was too low to produce visible light.
the high amount of dark matter during this time absorbed light fro

Explanation:

Step1: Analyze the first statement

The statement claims spacetime shrinks (false; it expands) and past mergers were less frequent (false; galaxies were closer, so mergers were more frequent). Thus, the statement is false.

Step2: Relate Hubble constant to universe age

The approximate age of the universe is inversely proportional to the Hubble constant ($t \approx \frac{1}{H_0}$). If $H_0$ is halved, $t$ doubles.

Step3: Explain pre-recombination opacity

Before recombination, free electrons scattered photons constantly, preventing light from traveling freely—making the universe opaque. The first option describes this interaction (though phrased as pair production/annihilation, it is the only relevant choice among the visible options).

Answer:

False
The universe would be twice as old after the recalculation.
Photons underwent pair production, and these particles underwent annihilation, at such a high rate to prevent the universe from being transparent.