Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 29, Problem 25E
The CMB contains roughly 400 million photons per m3. The energy of each photon depends on its wavelength. Calculate the typical wavelength of a CMB photon. Hint: The CMB is blackbody
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
The geometry of spacetime in the Universe on large scales is determined by the mean energy density of the matter in the Universe, ρ. The critical density of the Universe is denoted by ρ0 and can be used to define the parameter Ω0 = ρ/ρ0. Describe the geometry of space when: (i) Ω0 < 1; (ii) Ω0 = 1; (iii) Ω0 > 1. Explain how measurements of the angular sizes of the hot- and cold-spots in the CMB projected on the sky can inform us about the geometry of spacetime in our Universe. What do measurements of these angular sizes by the WMAP and PLANCK satellites tell us about the value of Ω0?
Problem 2: Black hole – the ultimate blackbody
A black hole emits blackbody radiation called Hawking radiation. A black hole with mass
M has a total energy of Mc², a surface area of 167G²M² /c*, and a temperature of
hc³/167²KGM.
a) Estimate the typical wavelength of the Hawking radiation emitted by a 1 solar
mass black hole (2 × 103ºkg). Compare your answer to the size of the black hole.
b) Calculate the total power radiated by a one-solar mass black hole.
c) Imagine a black hole in empty space, where it emits radiation but absorbs nothing.
As it loses energy, its mass must decrease; one could say "evaporates". Derive a
differential equation for the mass as a function of time, and solve to obtain an
expression for the lifetime of a black hole in terms of its mass.
Needs Complete typed solution with 100 % accuracy.
Chapter 29 Solutions
Astronomy
Ch. 29 - What are the basic observations about the universe...Ch. 29 - Describe some possible futures for the universe...Ch. 29 - What does the term Hubble time mean in cosmology,...Ch. 29 - Which formed first: hydrogen nuclei or hydrogen...Ch. 29 - Describe at least two characteristics of the...Ch. 29 - Describe two properties of the universe that are...Ch. 29 - Why do astronomers believe there must be dark...Ch. 29 - What is dark energy and what evidence do...Ch. 29 - Thinking about the ideas of space and time in...Ch. 29 - Astronomers have found that there is more helium...
Ch. 29 - Describe the anthropic principle. What are some...Ch. 29 - Describe the evidence that the expansion of the...Ch. 29 - What is the most useful probe of the early...Ch. 29 - What are the advantages and disadvantages of using...Ch. 29 - Would acceleration of the universe occur if it...Ch. 29 - Suppose the universe expands forever. Describe...Ch. 29 - Some theorists expected that observations would...Ch. 29 - There are a variety of ways of estimating the ages...Ch. 29 - Since the time of Copernicus, each revolution in...Ch. 29 - The anthropic principle suggests that in some...Ch. 29 - Penzias and Wilson’s discovery of the Cosmic...Ch. 29 - Construct a timeline for the universe and indicate...Ch. 29 - Suppose the Hubble constant were not 22 but 33...Ch. 29 - Assume that the average galaxy contains...Ch. 29 - The CMB contains roughly 400 million photons per...Ch. 29 - Following up on Exercise 29.27 calculate the...Ch. 29 - Continuing the thinking in Exercise 29.27 and...Ch. 29 - Continuing the thinking in the last three...Ch. 29 - There is still some uncertainty in the Hubble...Ch. 29 - It is possible to derive the age of the universe...
Additional Science Textbook Solutions
Find more solutions based on key concepts
What is the anatomical position? Why is it important that you learn this position?
Anatomy & Physiology (6th Edition)
All of the following terms can appropriately describe humans except: a. primary consumer b. autotroph c. hetero...
Human Biology: Concepts and Current Issues (8th Edition)
Why is petroleum jelly used in the hanging-drop procedure?
Laboratory Experiments in Microbiology (12th Edition) (What's New in Microbiology)
Flask A contains yeast cells in glucose-minimal salts broth incubated at 30C with aeration. Flask B contains ye...
Microbiology: An Introduction
Explain all answers clearly, with complete sentences and proper essay structure if needed. An asterisk (*) desi...
Cosmic Perspective Fundamentals
When a hydrochloric acid solution is combined with a potassium hydroxide solution, an acid-base reaction occurs...
Introductory Chemistry (6th Edition)
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
- ↓ C School SOLA webassign net Astronomy Textbook Microsoft Office Ho.. WebAssign The CMB contains roughly 400 million photons per m³. The energy of each photon depends on its wavelength. Calculate the typical wavelength of a CMB photon. Hint: The CMB is blackbody radiation at a temperature of 2.73 K. According to Wien's law, the peak wavelength in nanometers is given by Amax 3 x 106 T - Incognito (a) Calculate the wavelength at which the CMB is a maximum and, to make the units consistent, convert this wavelength from nanometers to meters.arrow_forwardA east.cengagenow.com/ilrn/takeAssignment/takeCovalentActivity.do?locator=assignment-take AM radio stations broadcast at frequencies between 530 kHz and 1700 kHz. (1 kHz = 10° /s.) For a station broadcasting at 1.17 × 10³ kHz, what is the energy of this radio wave? Note that Planck's constant is 6.63 x 10-34 J.s, and the speed of light is 3.00 x 10 m/s. Energy = Submit Answer Try Another Version 6 item attempts remaining Previous Next P Type here to search 12:03 PM 12/8/2021arrow_forwardH5.arrow_forward
- 20.) Twinkle Twinkle. A stable star of radius R has a mass density profile ρ(r)=α(1−r/R). Here, "stable" means that the star doesn't collapse under its own gravity. If the internal pressure at the core is provided solely by the radiation of photons, calculate the temperature at the core. Assume the star is a perfect black body and treat photons as a classical ideal gas. Use R=7×105 km and α=3 g/cm. Round your answer to the nearest kilokelvin. Using advanced olympiad physics concepts please answer carefullyarrow_forwardDoubly ionized lithium (Li++) emits a photon after transitioning from the n = 3 excited state directly back to the ground state. A) Calculate the mass of the lithium ion. (Atomic mass = 6.015123 u; electron mass = 5.485799 x 10-4 u) Express your answer in unified atomic mass units and to four significant figures. B) After the emission of the photon, the ion recoils. Calculate the recoil speed. Express your answer to three significant figures in meters/second.arrow_forwardThe photons that make up the cosmic microwave background were emitted about 380,000 years after the Big Bang. Today, 13.8 billion years after the Big Bang, the wavelengths of these photons have been stretched by a factor of about 1100 since they were emitted because lengths in the expanding universe have increased by that same factor of about 1100. Consider a cubical region of empty space in today's universe 1.00 m on a side, with a volume of 1.00 m³. What was the length so of each side and the volume V of this same cubical region 380,000 years after the Big Bang? So = Vo = Enter numeric value Today the average density of ordinary matter in the universe is about 2.4 × 10-27 kg/m³. What was the average density po of ordinary matter at the time that the photons in the cosmic microwave background radiation were emitted? Po = m m³ kg/m³arrow_forward
- Then, why the answers are different when I use different formulas, dB= 10log (I/ I0) and I= I0 10^-ax? The first one is 5e-5 W/cm^2 and the second one is 5e-23 W/cm^2.arrow_forwardWhat will be the energy associated with a blue photon (in Joules), if the frequency of the blue light is 650 THz (Terahertz (THz); 1 Tera – 1012y? [Hint: Use Planck's cquation: E = hf to calculate the photon energy! h - Planck's constant – 6,63 × 10-4 Js – 4.14 ×1015 eVs] A. 650×1012 J B. 6.5×10° J C. 4.3x1015 J D. 4.3×10-19 J E. 4.3x1019 Jarrow_forwardThe photons that make up the cosmic microwave background were emitted about 380,000 years after the Big Bang. Today, 13.8billion years after the Big Bang, the wavelengths of these photons have been stretched by a factor of about 1100 since they were emitted because lengths in the expanding universe have increased by that same factor of about 1100. Consider a cubical region of empty space in today’s universe 1.00 m on a side, with a volume of 1.00 m3. What was the length s0 of each side and the volume V0 of this same cubical region 380,000 years after the Big Bang? s0 = ? m V0 = ? m^3 Today the average density of ordinary matter in the universe is about 2.4×10−27 kg/m3. What was the average density ?(rho)0 of ordinary matter at the time that the photons in the cosmic microwave background radiation were emitted? (rho)0 = ? kg/m^3arrow_forward
- Suppose a star 1000 times brighter than our Sun (that is, emitting 1000 times the power) suddenly goes supernova. Using data from Table 7.3: (a) By what factor does its power output increase? (b) How many times brighter than our entire Milky Way galaxy is the supernova? (c) Based on your answers, discuss whether it should be possible to observe supernovas in distant galaxies. Note that there are on the order of observable galaxies, the average brightness of which is somewhat less than our own galaxy.arrow_forwardYou are studying a very distant quasar and are trying to determine how far away it is. The quasar is a very bright point-like light source, and there is only one relevant distance measuring technique applicable to objects at such a great distance. From a spectra of the quasar, you observe that it's Lyman alpha emission line (which would be at 121.6 nm in a laboratory sample of Hydrogen) is at 130 nm. What is the distance to this quasar in units of Mpc. [Hint: Think about what distance measuring technique we use for the very farthest objects in the universe. You will need to look up a special constant (who's value is uncertain) to complete this problem. The answer accounts for the possible range of uncertainty in the quantity you need to look up.]arrow_forwardThe peak intensity of the CMBR occurs at a wavelength of 1.1 mm. (a) What is the energy in eV of a 1.1-mm photon? (b) There are approximately 109 photons for each massive particle in deep space. Calculate the energy of 109 such photons. (c) If the average massive particle in space has a mass half that of a proton, what energy would be created byconverting its mass to energy? (d) Does this imply that space is “matter dominated”? Explain briefly.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Modern PhysicsPhysicsISBN:9781111794378Author:Raymond A. Serway, Clement J. Moses, Curt A. MoyerPublisher:Cengage Learning
Modern Physics
Physics
ISBN:9781111794378
Author:Raymond A. Serway, Clement J. Moses, Curt A. Moyer
Publisher:Cengage Learning