EBK PHYSICS FOR SCIENTISTS & ENGINEERS
5th Edition
ISBN: 9780134296074
Author: GIANCOLI
Publisher: VST
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Chapter 44, Problem 9Q
To determine
The change in views regarding the universe if the red shift of the spectral lines of galaxies was due to something other than expansion.
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Explain why it only appears that we are at the center of expansion of the universe and why an observer in another galaxywould see the same relative motion of all but the closest galaxies away from her
(a) Calculate the approximate age of the universe from the average value of the Hubble constant, H0 = 20km/s ⋅ Mly . To do this, calculate the time it would take to travel 1 Mly at a constant expansion rate of 20 km/s. (b) If deceleration is taken into account, would the actual age of the universe be greater or less than that found here? Explain.
Assume that the universe is expanding at an increasing rate, and explain why.
Chapter 44 Solutions
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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
- Some theorists expected that observations would show that the density of matter in the universe is just equal to the critical density. Do the current observations support this hypothesis?arrow_forwardIt is possible to derive the age of the universe given the value of the Hubble constant and the distance to a galaxy, again with the assumption that the value of the Hubble constant has not changed since the Big Bang. Consider a galaxy at a distance of 400 million light-years receding from us at a velocity, v. If the Hubble constant is 20 km/s per million light-years, what is its velocity? How long ago was that galaxy right next door to our own Galaxy if it has always been receding at its present rate? Express your answer in years. Since the universe began when all galaxies were very close together, this number is a rough estimate for the age of the universe.arrow_forwardIf p = 2.7 x 10-27 kgm-3, what is the radius of curvature R, of Einstein's static universe? How long would it take a photon to circumnavigate such a universe?arrow_forward
- The Andromeda Galaxy is a member of the Local Group of galaxies. It is approaching us. Does this mean that the Hubble Law is wrong? Why or why not? Explain.arrow_forward(a) Calculate the approximate age of the universe from the average value of the Hubble constant, H0 = 20km/s ⋅ Mly . To do this, calculate the time itwould take to travel 1 Mly at a constant expansion rate of 20 km/s.(b) If deceleration is taken into account, would the actual age of the universe be greater or less than that found here? Explain.arrow_forwardDoes the universe have a center? Explain.arrow_forward
- A certain galaxy is observed to be receding from the Sun at a rate of 8000 km/sec. The distance to this Galaxy I measured independently and found to be 1.4 x 10 to the eighth power pc. Using these data , what is the value of the Hubble constant ?arrow_forwardTo get an idea of how empty deep space is on the average, perform the following calculations: (a) Find the volume our Sun would occupy if it had an average density equal to the critical density of 10-26 kg / m3 thought necessary to halt the expansion of the universe. (b) Find the radius of a sphere of this volume in light years. (c) What would this radius be if the density were that of luminous matter, which is approximately 5% that of the critical density? (d) Compare the radius found in part (c) with the 4-ly average separation of stars in the arms of the Milky Way.arrow_forwardWith the aid of a diagram, explain the physical origin of cosmological redshift in an expanding universe, and how this differs from the Doppler shift due to relative motion. Observations of distantgalaxies indicate that their recession velocities, v, and their distances, d, follow a Hubble Law:v = H0d, where H0 is a constant. Using the analogy of an expanding grid or ruler, demonstratethat Hubble’s Law indicates that the Universe is undergoing uniform expansion.arrow_forward
- 5.4 In a negatively curved universe containing only matter (20 < 1, K = -1), show that the present age of the universe is given by the formula 1 2- S20 cosh- 2(1 – 20)3/2 Hoto (5.118) 1- 20 Assuming Ho = 68 km s Mpc1, plot to as a function of 20 in the range 0 < 20 s 1. %3Darrow_forwardWhich of the following is least reasonable regarding cosmic background radiation (CBR)? Group of answer choices CBR correponds to a solar temperature of about 6,000 degrees and implies that the Universe was about 3K right after the Big Bang. The original CBR corresponded to a much higher temperature, but the expansion of the Universe has caused to be strongly Doppler-shifted toward longer wavelengths. Satellite-based telescopes were crucial to the discovery of CBR because much of the CBR spectrum cannot be detected through our atmosphere. The motion of the Earth produces a Doppler shift, which causes CBR to appear a little hotter in front of us and a little colder behind us. Data for CBR is collected by pointing telescopes to regions that do not appear to have any bright objects.arrow_forwardUsing our example from the previous unit, let's try to determine the Hubble time for this example universe. You were given that a good representative galaxy receded at a speed of 4000 km/s and was found to be 20 Mpc away. With that in mind, what would the age of that universe be in years (aka what is that universe's Hubble time)? Go ahead and take the number of kilometers per Mpc to be approximately 3.1*10^19 km/Mpc. While this problem may look scary at first, this is really just bringing you full circle to one of the unit conversion problems you encountered at the beginning of this course.arrow_forward
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