Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
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Chapter 25, Problem 37Q
To determine
The critical density of the universe and importance of critical density to the cosmologists.
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Suppose that you have a flat universe that has matter and dark energy with wd = -2/3 & Ωd,0 =0.7
At the time when light with z = 1 was emitted from a distant galaxy what was the ratio Ɛd /Ɛm ?
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make to cosmology?
What are the possible fates for the universe? What do they depend on? What appears to be the actual fate of the universe, according to current cosmology?
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Chapter 25 Solutions
Universe: Stars And Galaxies
Ch. 25 - Prob. 1QCh. 25 - Prob. 2QCh. 25 - Prob. 3QCh. 25 - Prob. 4QCh. 25 - Prob. 5QCh. 25 - Prob. 6QCh. 25 - Prob. 7QCh. 25 - Prob. 8QCh. 25 - Prob. 9QCh. 25 - Prob. 10Q
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- Why cant an open universe have a center? How can a closed universe not have a center?arrow_forwardI asked the following question and was given the attached solution: Suppose that the universe were full of spherical objects, each of mass m and radius r . If the objects were distributed uniformly throughout the universe, what number density (#/m3) of spherical objects would be required to make the density equal to the critical density of our Universe? Values: m = 4 kg r = 0.0407 m Answer must be in scientific notation and include zero decimal places (1 sig fig --- e.g., 1234 should be written as 1*10^3) I don't follow the work and I got the wrong answer, so please help and show your work as I do not follow along easily thanksarrow_forwardWhy can't we see past the cosmological horizon? The universe extends only to this horizon. Beyond the cosmological horizon, the Universe curves away from us, like the surface of the Earth. O We do not have telescopes big enough. Beyond the cosmological horizon, we are looking back to a time before the universe had formed.arrow_forward
- 1. The current (critical) density of our universe is pe = 10-26kg/m³. Assume the universe is filled with cubes with equal size that each contain one person of m = 100kg. What would the length of the side of such a cube have to be in order to give the correct critical density? How many hydrogen atoms would you need in a box of 1 m³ to reach the critical density? The matter we know, which consists mostly of hydrogen, constitutes only 4.8% of the current critical energy density of our universe. So how many hydrogen atoms are actually in a box of 1 m3 in our universe? Deep space is very empty and a much better vacuum than we can obtain on earth in a laboratory.arrow_forwardAssume the observable Universe is charge neutral, and that it contains n nuclei (hydrogen plus helium nuclei, ignoring other elements). Take the helium mass fraction as 1/4. How many electrons are there in the observable Universe? Enter your answer in scientific notation with one decimal place. Values: n = 1*10^80arrow_forwardI'm doing a debate about Kalam cosmological. I need to have an example of something out of nothing (Or maybe we can't prove the cause)? Can you help give 5 modern physics example?arrow_forward
- What is the role of symmetry in fundamental physics? Provide examples of symmetry principles in particle physics and cosmology.arrow_forwardAccording to the cosmological principle, our place in the universe does not appear to be particularly special compared to any other and it allows us to make predictions about the development of other galaxies and the evolution of the universe. The principle relies on Hubble's results that the universe appears to be the same in all directions (aka it is Question Blank 1 of 2) {hint: one word} and that any large region of space at a given distance from us appears like any other large region of space at a similar distance from us (aka it is Question Blank 2 of 2) {hint: one word}arrow_forward
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