Concept explainers
The reason why the astronomers say that the universe is homogeneous.
Answer to Problem 1QP
Option (d).
Explanation of Solution
The meaning of word homogeneous is same in all locations. Based on cosmological principle the universe is both homogeneous and isotropic.
The universe appears homogeneous when it is viewed in large scale, because the forces are expected to act uniformly throughout the universe. Hence there is no irregularity in large scale structure.
Conclusion:
Since the universe appears same in all locations option (d) is the best suited answer.
Since the universe appears same in all locations option (a) is not the correct answer.
Since the universe appears same in all locations option (b) is not the correct answer.
Since the universe appears same in all locations option (c) is not the correct answer.
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Chapter 21 Solutions
21ST CENTURY ASTRONOMY:STARS+GALAXIES
- 1. Why big bang theory the most accepted theory on the origin of the universe? 2. What does the Hindu text Rigveda describe about the universe?\ 3. How Did everything as we know it today, come into being?arrow_forwardThere is still some uncertainty in the Hubble constant. (a) Current estimates range from about 19.9 km/s per million light-years to 23 km/s per million light-years. Assume that the Hubble constant has been constant since the Big Bang. What is the possible range in the ages of the universe? Use the equation in the text, T0=1H , and make sure you use consistent units. (b) Twenty years ago, estimates for the Hubble constant ranged from 50 to 100 km/s per Mps. What are the possible ages for the universe from those values? Can you rule out some of these possibilities on the basis of other evidence?arrow_forwardGalaxies are found in the “walls” of huge voids; very few galaxies are found in the voids themselves. The text says that the structure of filaments and voids has been present in the universe since shortly after the expansion began 13.8 billion years ago. In science, we always have to check to see whether some conclusion is contradicted by any other information we have. In this case, we can ask whether the voids would have filled up with galaxies in roughly 14 billion years. Observations show that in addition to the motion associated with the expansion of the universe, the galaxies in the walls of the voids are moving in random directions at typical speeds of 300 km/s. At least some of them will be moving into the voids. How far into the void will a galaxy move in 14 billion years? Is it a reasonable hypothesis that the voids have existed for 14 billion years?arrow_forward
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