Foundations of Astronomy (MindTap Course List)
14th Edition
ISBN: 9781337399920
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 17, Problem 22RQ
What percentage of matter is ordinary matter? What percentage is dark matter? What makes up the rest of the Universe’s density?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
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.
Your friends are talking about Olber's Paradox:
Friend 1: When the universe was quite young, it was also quite small, and therefore light
was trapped inside the universe. This is why we don't see light from the edge of the
universe in every direction.
Friend 2: No, Olber's Paradox describes only light from stars, not from galaxies, and why
you can't use light from distant stars to see at night.
Friend 3: You're both right and you're both wrong. The paradox concerns itself with the
expansion of the universe, and explains why light from the early universe was able to be
released.
Are any of them right, in part or in whole?
Does Hubble's Law work well for galaxies in the Local Group (such as Andromeda)?
No, because dark energy is accelerating the universe's expansion over those distances.
No, because we do not know the precise value of Ho.
No, because Hubble did not know the Local Group existed when he discovered his law.
Yes, it works well for all galaxies.
No, because galaxies in the Local Group are bound gravitationally together.
Chapter 17 Solutions
Foundations of Astronomy (MindTap Course List)
Ch. 17 - Is cosmology the study of the Universe, the...Ch. 17 - Is a cosmologist an astronomer? Is an astronomer a...Ch. 17 - How does the darkness of the night sky tell you...Ch. 17 - Explain the differences among the observable...Ch. 17 - Prob. 5RQCh. 17 - Prob. 6RQCh. 17 - Prob. 7RQCh. 17 - Prob. 8RQCh. 17 - Prob. 9RQCh. 17 - Prob. 10RQ
Ch. 17 - Prob. 11RQCh. 17 - If you accept the cosmological principle, how can...Ch. 17 - Why cant an open universe have a center? How can a...Ch. 17 - In which type of model universe is space-time...Ch. 17 - In which type of model universe is space-time...Ch. 17 - What is the fate of a closed universe? In what...Ch. 17 - In which model universe does the average density...Ch. 17 - Prob. 18RQCh. 17 - What evidence shows that the Universe is...Ch. 17 - Why couldnt atomic nuclei exist when the Universe...Ch. 17 - Why are measurements of the current density of the...Ch. 17 - What percentage of matter is ordinary matter? What...Ch. 17 - How does the inflationary universe hypothesis...Ch. 17 - Prob. 24RQCh. 17 - What is the evidence that the Universe was...Ch. 17 - Prob. 26RQCh. 17 - If the Universe is negatively curved, and dark...Ch. 17 - What is the difference between hot dark matter and...Ch. 17 - Prob. 29RQCh. 17 - What evidence can you cite that the Universe's...Ch. 17 - Prob. 31RQCh. 17 - Reasoning by analogy often helps make complicated...Ch. 17 - Prob. 33RQCh. 17 - In science, wishing something to be true does not...Ch. 17 - Prob. 1PCh. 17 - Prob. 2PCh. 17 - Prob. 3PCh. 17 - Measure the lengths of the two arrows in the left...Ch. 17 - Prob. 5PCh. 17 - Prob. 6PCh. 17 - Find the wavelength of maximum intensity of the...Ch. 17 - Prob. 8PCh. 17 - Prob. 9PCh. 17 - Prob. 10PCh. 17 - Prob. 11PCh. 17 - Prob. 12PCh. 17 - Prob. 1SOPCh. 17 - Prob. 2SOPCh. 17 - Prob. 1LTLCh. 17 - Prob. 2LTLCh. 17 - Prob. 3LTLCh. 17 - Prob. 4LTLCh. 17 - Prob. 5LTLCh. 17 - Prob. 6LTL
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- What evidence shows that the Universe is expanding? What evidence shows that the Universe began with a Big Bang?arrow_forwardWhat is dark energy and what evidence do astronomers have that it is an important component of the universe?arrow_forwardWhat is the difference between hot dark matter and cold dark matter? How does this difference affect cosmology?arrow_forward
- What does it mean to say that the universe is expanding? What is expanding? For example, is your astronomy classroom expanding? Is the solar system? Why or why not?arrow_forwardWhy cant an open universe have a center? How can a closed universe not have a center?arrow_forwardIf all distant galaxies are expanding away from us, does this mean we’re at the center of the universe?arrow_forward
- The light coming from stars is closer to red (long wavelength, low frequency) than we would expect. What does this imply? Your answer: the universe is expanding the universe is rotating the universe is shrinking the universe is staticarrow_forwardWhat has occurred after the Big Bang? Objects in the universe have reached a critical density. Objects that were once close together have moved apart as space expanded. Space expanded without affecting the distances between objects. Objects that were once close together have expanded apart into already existing space.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 = 5*10^80arrow_forward
- What exactly is dark matter?arrow_forwardAn astronomer observed the motions of some galaxies. Based on his observations, he made the following statements. Which one of them is most likely to be false? Take Hubble's constant to be 67 km/s/Mpc. A. A galaxy observed to be moving away from us at a speed of 70 km/s is at a distance of about 1 Mpc from us. B. A galaxy observed to be moving away from us at a speed of 700 km/s is at a distance of about 10 Mpc from us. C. A galaxy observed to be moving away from us at a speed of 7000 km/s is at a distance of about 100 Mpc from us. D. A galaxy observed to be moving away from us at a speed of 70000 km/s is at a distance of about 1 Gpc from us. Is the answer D? Thank you!arrow_forward
arrow_back_ios
arrow_forward_ios
Recommended textbooks for you
Stars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
AstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStax
An Introduction to Physical SciencePhysicsISBN:9781305079137Author:James Shipman, Jerry D. Wilson, Charles A. Higgins, Omar TorresPublisher:Cengage Learning
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
Astronomy
Physics
ISBN:9781938168284
Author:Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher:OpenStax
An Introduction to Physical Science
Physics
ISBN:9781305079137
Author:James Shipman, Jerry D. Wilson, Charles A. Higgins, Omar Torres
Publisher:Cengage Learning
General Relativity: The Curvature of Spacetime; Author: Professor Dave Explains;https://www.youtube.com/watch?v=R7V3koyL7Mc;License: Standard YouTube License, CC-BY