Question

question 18
what is the cosmological principle?
the universe appears the same in all directions.
the recessional speed of a galaxy is directly proportional to its distance away from earth.
the redshifts that are seen in distant galaxies is due to the expansion of spacetime.
the speed of light is constant while in the vacuum of space.
question 19
1 pts
what is the different between rich clusters and poor clusters of galaxies?
rich clusters have large amounts of gold atoms while poor clusters have little to no gold atoms present.
rich clusters contains all elements of the period table while poor clusters on contain hydrogen and helium.
rich clusters are comprised of many galaxies while poor clusters have fewer galaxies in comparison.
rich clusters have very few stellar - mass black holes while poor cluster have many stellar - mass black holes.
question 20
1 pts
which of the following is not a consequence of hubbles law?
the observable universe is expanding.
earth is at the center of the universe.
the universe had a beginning.
the universe had a mass density that was higher in the past.
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Explanation:

• Question 18: The Cosmological Principle states the universe is isotropic (same in all directions) and homogeneous.
• Question 19: Galaxy clusters are classified by the number of galaxies; rich clusters have many, poor clusters have few.
• Question 20: Hubble’s Law implies universal expansion, a beginning (Big Bang), and higher past density, but not Earth being the center.

Answer:

Question 18: The universe appears the same in all directions.
Question 19: Rich clusters are comprised of many galaxies while poor clusters have fewer galaxies in comparison.
Question 20: Earth is at the center of the universe.