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Chapter 21: Problem 8

The CMB includes information about (select all that apply) a. the age of the universe. b. the temperature of the early universe. c. the density of the early universe. d. density fluctuations in the early universe. e. the motion of Earth around the center of the Milky Way.

Short Answer

Expert verified
a, b, c, d

Step by step solution

01

Identify Relevant Topics

The Cosmic Microwave Background (CMB) radiation contains information about various aspects of the early universe. The task requires identifying all applicable topics from a given list.
02

Analyzing Option a

The CMB can be used to estimate the age of the universe by measuring the expansion rate and extrapolating back to the Big Bang. Therefore, option (a) the age of the universe is correct.
03

Analyzing Option b

The CMB provides a snapshot of the temperature of the universe approximately 380,000 years after the Big Bang. Thus, option (b) the temperature of the early universe is correct.
04

Analyzing Option c

By analyzing the CMB, scientists can infer the density of the universe at the time the CMB was released. Hence, option (c) the density of the early universe is correct.
05

Analyzing Option d

The CMB exhibits tiny fluctuations in temperature, which correspond to density variations in the early universe. Therefore, option (d) density fluctuations in the early universe is correct.
06

Analyzing Option e

The CMB does not provide information related to the motion of Earth around the center of the Milky Way. Thus, option (e) is incorrect.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Age of the Universe
The Cosmic Microwave Background (CMB) is like a cosmic fossil, helping us estimate the age of the universe. When scientists measure the expansion rate of the universe through the CMB, they can trace this back to the Big Bang. This way, they determine the universe's age to be about 13.8 billion years. The data from the CMB provides precise measurements, making it a cornerstone in understanding our universe's timeline.
Temperature of the Early Universe
The CMB offers a snapshot of the universe when it was just 380,000 years old, showcasing what scientists call the 'surface of last scattering.' This period was when the universe cooled enough for protons and electrons to form neutral hydrogen atoms, letting light travel freely. The temperature at this time was about 3000 K. Today, due to the expansion of the universe, we see the CMB at a much cooler temperature of about 2.7 K. This shift also provides vital clues about the universe's development.
Density of the Early Universe
Analyses of the CMB reveal valuable data about the density of the universe at its early stages. By examining the radiation, scientists deduce how much matter, both dark and visible, was present. This information is crucial, as it helps in understanding the universe's structure and behavior. The initial density set the stage for the formation of galaxies, stars, and other cosmic structures. By comparing these densities, researchers gain insights into how the universe evolved from the Big Bang to its current state.
Density Fluctuations
One of the intriguing features of the CMB is its tiny temperature fluctuations, which reflect density variations in the early universe. These fluctuations were the seeds of all the structures we see in the universe today. Even slight differences in density allowed gravity to pull matter together over billions of years, forming galaxies and clusters of galaxies. Studying these fluctuations helps scientists test various models of the universe's origins and evolution, providing a deeper understanding of cosmic formation.

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Most popular questions from this chapter

You observe a distant quasar in which a spectral line of hydrogen with rest wavelength \(\lambda_{\text {rest }}=121.6 \mathrm{nm}\) is found at a wavelength of \(547.2 \mathrm{nm}\). What is its redshift? When the light from this quasar was emitted, how large was the universe compared to its current size?

Why is the Milky Way Galaxy not expanding together with the rest of the universe? a. It is not expanding because it is at the center of the expansion. b. It is expanding, but the expansion is too small to measure. c. The Milky Way is a special location in the universe. d. Local gravity dominates over the expansion of the universe.

The average density of normal matter in the universe is \(4 \times 10^{-28} \mathrm{kg} / \mathrm{m}^{3} .\) The mass of a hydrogen atom is \(1.66 \times 10^{-27} \mathrm{kg}\) On average, how many hydrogen atoms are there in each cubic meter in the universe?

The Big Bang theory predicted (select all that apply) a. the Hubble law. b. the cosmic microwave background radiation. c. the cosmological principle. d. the abundance of helium. e. the period-luminosity relationship of Cepheid variables.

Some galaxies have redshifts \(z\) that if equated to \(v_{\mathrm{r}} / \mathrm{c}\) correspond to velocities greater than the speed of light. Special relativity is not violated in this case a. because of relativistic beaming. b. because of superluminal motion. c. because redshifts carry no information. d. because these velocities do not measure motion through space
See all solutions

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