UNIVERSE (LOOSELEAF):STARS+GALAXIES
6th Edition
ISBN: 9781319115043
Author: Freedman
Publisher: MAC HIGHER
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Chapter 26, Problem 42Q
To determine
Whether the string theory an attempt to formulate a theory of quantum gravity, and the dimensions of space and time that might exist if the theory is correct.
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Check out a sample textbook solutionStudents have asked these similar questions
1. For centuries, we accpeted Newton's 2nd Law as the standard model for motion. Then Einstien came along and siggested a modification in cases of high velocity. The Lorenz factor:
γ(v)=(1/square-root of 1−(v^2/c^2))
a) The constant (c) is the speed of light, which is 3 * 10^8 m/s. What is the lim as v approaches 400 γ(v)? You will have to track many decimal places to see a difference from 1. A bullet travels 400 m/s; this limit indicates that time dilation is extremely small (and basically negigible) at that speed.
b) In the movie Interstellar, time dialation occurs as 1 hour on the water planet corresponds to 7 years on earth. What is the factor γ in this case (what is the ratio of 7 years to 1 hour)?
c) If we rearrange the equation for γ and solve for v, we get:
v = c square-root of (γ^2 - 1/γ^2)
What velocity v is necesary to get the γ you found in part (b)?
d) What is the lim as v approaches c γ(v) ?…
The mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is chosen as the center, how large is the radius of a spherical surface centered at the point so that the mass enclosed in the surface will become a blackhole observed by someone outside the surface?
A. 4.2 trillion light years
B. 420 billion light years
C. 42 billion light years
D. 4.2 billion light years
Is the answer D? Thanks!
Name:
Hubble Distances
Redshift z parameter
The relativistic redshift is parametrized by z and given by
Δ
In terms of the scale factor,
2=
X
do - de
de
1+z=
ao
a
(2)
Problem 01. Find the redshift z for a Hydrogen spectral line originally at 656 nm which
has been observed at a wavelength of 1.64 μm.
Astro 001 Fall 2022
Problem 02. How much smaller was the universe when this light was emitted?
U₁ = DHO
Using the redshift to measure the velocity, we find
D~
(1)
0.1 Hubble's Law
Hubble's Law states that the recession velocity of a redshifted galaxy is given by the product
of the distance and the Hubble constant.
(3)
ZC
Ho
where c = 3 x 108 m/s and Ho = 2.3 x 10-18 s in standard units. The standard measurement
of the Hubble constant is Ho = 71 (km/s)/Mpc.
Problem 03. What is the distance in Mpc and ly to the galaxy measured in problem 01?
1 pc = 3.26 ly.
Chapter 26 Solutions
UNIVERSE (LOOSELEAF):STARS+GALAXIES
Ch. 26 - Prob. 1QCh. 26 - Prob. 2QCh. 26 - Prob. 3QCh. 26 - Prob. 4QCh. 26 - Prob. 5QCh. 26 - Prob. 6QCh. 26 - Prob. 7QCh. 26 - Prob. 8QCh. 26 - Prob. 9QCh. 26 - Prob. 10Q
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