Classical vs. Cosmological Redshift LAB
For this lab, you’ll use the following lab write-up as a template. Record
your answers to each question and activity this document, and upload
as a .doc or .pdf document to the following module item for grading:
“Classical vs. Cosmological Redshift Lab Submission”
1) Write a paragraph or two summarizing what you learned from the
background information. Include anything you found interesting,
and propose how you think this information would be helpful in
astronomy and astrophysics.
2) Consider the following formula:
Here z is the redshift and the lambdas represent the observed and
emitted wavelengths for the light in consideration. What does a
redshift of zero mean? What does a redshift of one mean? How
many times longer is the observed wavelength than the emitted
wavelength if the redshift is seven?
3) Consider the following link:
The lookback time tells us how long the light has taken to reach
us. Why is this not equal to the current distance to the galaxy?
In order to calculate the current distance to the galaxy, several
assumptions about the Universe must be made. How fast is the
Universe expanding? Has it always been expanding at this rate?
These are questions beyond the scope of this lab.
4) In astrophysics we assume that there is no preferred spot in the
Universe and that the laws of physics are the same everywhere in
the Universe. As a result, we would expect objects to be moving
randomly throughout space.
Let’s assume that all of the galactic motion in the Universe is
classical in nature. What would we expect to see as far as redshift
and blueshift are concerned? Would this change in any significant
way with distance? Why or why not?
Now assume that all of the galactic motion in the Universe is
cosmological in nature. What would we expect to see as far as
redshift and blueshift are concerned? Would this change in any
significant way with distance? Why or why not?
5) In reality the galactic motion in the Universe is a mixture of the
two. Consider looking at galaxies with several different redshift
values. Consider the following two cases:
a. Classical motion dominates over cosmological motion. The
magnitude of the random velocity is greater than the
magnitude of the recessional velocity. Now what would we
expect to see as far as redshift and blueshift are concerned?
Would this change in any significant way with distance? Why
or why not?
b. Again repeat, but now assume that cosmological motion
dominates over classical motion. The magnitude of the
recessional velocity is greater than the magnitude of the
6) Consider that light was emitted from a galaxy with a wavelength
of 2.50 * 10
meters. What would be the observed wavelength
for the following redshifts?
7) Assume that visible light is in the range of 400 nanometers to 700
nanometers. Which of the above would result in observations
being made in the visible light spectrum?
8) Write a two paragraph conclusion of what you have done. Include
any results that may have surprised you.
PLEASE SEE THE ATTACHMENTS !!