Question

question 23
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 from the first generation of galaxies.

question 24 1 pts
the study of the origin and evolution of the universe is called ________.

• volcanology
• geology
• astronomy
• cosmetology
• cosmology

question 25 1 pts
can a spiral galaxy turn into an elliptical galaxy? if so, explain how. if not, explain why not.
type your two (2) answers in the text field below.
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Explanation:

• Question 23: Before recombination, the universe was hot enough that photons frequently interacted with free electrons and protons (via scattering), preventing light from traveling freely. Pair production/annihilation is not the key reason for opacity here; dust and stars did not exist yet.
• Question 24: Cosmology is the branch of science focused on the origin and evolution of the universe. Volcanology studies volcanoes, geology studies Earth’s structure, astronomy is the broader study of celestial objects, and cosmetology is about beauty treatments.
• Question 25: Spiral galaxies can merge with other galaxies. Mergers disrupt their spiral structure, randomizing the orbits of stars and gas, leading to the smooth, elliptical shape of elliptical galaxies.

Answer:

Question 23: Photons underwent pair production, and these particles underwent annihilation at such a high rate to prevent the universe from being transparent.
Question 24: Cosmology
Question 25: Yes; spiral galaxies can turn into elliptical galaxies through galaxy mergers, which disrupt their spiral structure and randomize stellar orbits.