What do astronomers mean when they say that the universe is homogeneous? a. All

Question

What do astronomers mean when they say that the universe is homogeneous? a. All stars in all galaxies have planetary systems just like ours. b. The universe looks exactly the same no matter what direction you look. c. Galaxies are generally distributed similarly throughout the universe. d. Generally speaking, there is little difference between conditions on Earth, in the sun, or in outer space. e. The universe looks the same at all times in its history. What do astronomers mean when they say that the universe is isotropic? a. Far away parts of the universe look just like nearby parts. b. All galaxies are spiral galaxies like our own. c. Intergalactic gas has the same density everywhere in the universe. d. The laws of physics apply everywhere in the universe. e. The universe looks the same no matter what direction you look. According to Hubble's law, as the distance of a galaxy _____ its _____ increases. a. increases; luminosity b. increases; recessional velocity c. decreases luminosity d. decreases; recessional velocity e. decreases; peculiar velocity If we lived in a galaxy 1 billion light-years from our own, what would we see? a. a universe 1 billion years younger than ours b. a universe 1 billion years older than ours c. much the same universe we see here d. a universe expanding at a slower rate than we see from Earth e. a universe expanding at a faster rate than we see from Earth The spectra of most galaxies tell us that a. most galaxies appear to be moving away from us. b. their light comes predominantly from objects other than stars. c. most galaxies contain clouds of gas that are absorbing their favorite wavelengths. d. galaxies in the past rotated at a faster rate than they do today. e. galaxies are rushing through space at high speeds. Why are some galaxies' spectra blueshifted rather than redshifted? a. Some distant galaxies are gravitationally lensed. b. Some distant galaxies show the universe was contracting before the Big Bang started. c. nearby galaxies have vigorous star formation and are much bluer than others. d. Some distant galaxies have AGN at their centers. e. For some nearby galaxies the attraction of Milky Way dominates over the Hubble expansion of space.

Explanation / Answer

1 - c homogeneous means it's density is same throughout and also looks the same everywhere

2 - e universe looks the same in every direction from the center

3 - b

4 - b

5 - a

6 - b

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