Today you need your:
•
Learning Astronomy Activity 26 - Determining
the Expansion Rate and Age of the Universe
•
A-B-C-D True/False sheet
•
Learning Astronomy Activity 20 - Stuff Between
the Stars
Change in lecture policy starting right now:
All cell phones must be silenced and put away for the duration of the class.
There is just too much distraction going on during the 50 minutes we need to be
focusing on learning and being engaged in the process.
Your neighboring students will appreciate your doing so, along with no
distractions from laptops being used for anything other than taking notes.
Thank you!
Review of Hubble Law
(Expansion Rate and Age
of the Universe)
Hubble’s law using 18 galaxies
5000
a
b
c
Recessional velocity (km/sec)
4500
Younger
4000
3500
3000
Older
2500
2000
1500
1000
500
0
0
10
20
30
40
50
60
70
80
90
Distance (Mpc)
FIGURE 26.3
Steeper slope means faster velocities/distance for galaxies;
flatter slope means slower velocities/distance for galaxies.
Age: _____________________ years
15. Quantitatively (use ratios) compare your maximum age for the universe to the age of the
Sun (5 billion years) and to the age of the oldest stars in the Milky Way (approximately 12.5
billion years). Comment on your findings.
16. The long-standing view of the universe before Edwin Hubble’s observations was that everything was standing still. Discuss how your analysis either supports or refutes this claim.
When Hubble made his first observations, he determined a Hubble constant of 500 km/s/Mpc.
During the years 1950 to 1960, there were serious disagreements about the value for the Hubble
constant. One group stated that it was 60 km/s/Mpc; another group said it was closer to
100 km/s/Mpc. The current results from the Planck mission give the best estimate of the Hubble
constant: 67.8 ± 0.77 km/s/Mpc (see http://map.gsfc.nasa.gov/universe/bb_tests_exp.html).
16. The long-standing view of the universe before Edwin Hubble’s observations was that everything was standing still. Discuss how your analysis either supports or refutes this claim.
When Hubble made his first observations, he determined a Hubble constant of 500 km/s/Mpc.
During the years 1950 to 1960, there were serious disagreements about the value for the Hubble
constant. One group stated that it was 60 km/s/Mpc; another group said it was closer to
100 km/s/Mpc. The current results from the Planck mission give the best estimate of the Hubble
constant: 67.8 ± 0.77 km/s/Mpc (see http://map.gsfc.nasa.gov/universe/bb_tests_exp.html).
17. Summarize how our knowledge of the universe has changed with the more exact value of
today.
How our view of the Universe has changed
Activity 26: Finding the Expansion Rate and the
Age of the Universe
©2014 W. W. Norton & Company, Inc.
10
Post-26.1: Edwin Hubble came up with a slope of 500 km/s/Mpc when he first graphed his measurements.
What was the age of the universe based on that value?
a.
b.
c.
d.
2 billion years old
13.8 billion years old
6,000 years old
210,000 years old
©2014 W. W. Norton & Company, Inc.
11
Post-26.1: Edwin Hubble came up with a slope of 500 km/s/Mpc when he first graphed his measurements.
What was the age of the universe based on that value?
a.
b.
c.
d.
2 billion years old
13.8 billion years old
6,000 years old
210,000 years old
©2014 W. W. Norton & Company, Inc.
12
Post-26.2: Around 1975 there was a definite dichotomy in the
accepted value for the Hubble constant (Ho): 100 km/s/Mpc
versus 50 km/s/Mpc. What would be the implied age of the
universe for Ho = 100 km/s/Mpc? a.
b.
c.
d.
2.5 billion years
5 billion years
10 billion years
20 billion years
©2014 W. W. Norton & Company, Inc.
13
Post-26.2: Around 1975 there was a definite dichotomy in the
accepted value for the Hubble constant (Ho): 100 km/s/Mpc
versus 50 km/s/Mpc. What would be the implied age of the
universe for Ho = 100 km/s/Mpc? a.
b.
c.
d.
2.5 billion years
5 billion years
10 billion years
20 billion years
©2014 W. W. Norton & Company, Inc.
14
When Hubble made his first observations, he determined a Hubble constant of 500 km/s/Mpc.
During the years 1950 to 1960, there were serious disagreements about the value for the Hubble
constant. One group stated that it was 60 km/s/Mpc; another group said it was closer to
100 km/s/Mpc. The current results from the Planck mission give the best estimate of the Hubble
constant: 67.8 ± 0.77 km/s/Mpc (see http://map.gsfc.nasa.gov/universe/bb_tests_exp.html).
17. Summarize how our knowledge of the universe has changed with the more exact value of
today.
age of the
Post-26.3: If the universe were not expanding, which of the
graphs show here would represent that fact?
a.
b.
c.
d.
graph (a): y = mx + b
graph (b): y = -mx + b
graph (c): y = constant
none of these
©2014 W. W. Norton & Company, Inc.
16
Post-26.3: If the universe were not expanding, which of the
graphs show here would represent that fact?
a.
b.
c.
d.
graph (a): y = mx + b
graph (b): y = -mx + b
graph (c): y = constant
none of these
©2014 W. W. Norton & Company, Inc.
17
This concludes Activity 26: Finding the Expansion
Rate and the Age of the Universe
©2014 W. W. Norton & Company, Inc.
18