Robert L Zimmerman
ASTR 123, Assignment #7 Large Scale
Structure
Assigned Nov 17, 2009----Due Nov 24
Answer the questions and return images from the Web. Place all images in a word processor and include under each picture a brief description of the image.
Questions
1,
Explain the Cosmological Principle, i.e. what does it mean for the universe to
be isotropic and homogeneous. (Text page 711)?
2.
On page 717 there is an analogy of the fate of the universe with the motion of
a rocket ship. The fate of the rocket is determined by the mass of Earth. Draw the diagram in Figure 26.14 and
explain the curves and relate them to the analogy to the spaceship. What
parameter determines the fate of the universe . What is the meaning of critical density and what is its
value compared with the number of hydrogen atom per cubic meter.
3.
Draw the Hubble diagram in figure 26.11. Explain how the diagram can be
used to determine that the universe is accelerating (page 707).
4.
1946 George Gamow suggested the Universe began with a Hot Big Bang. What
was he trying to explain and why did he say that the universe must have been
very hot in the past? (Notes)
Images
5. The satellite WMAP (Wilkinson
Microwave Anisotropy Probe) has advanced our knowledge of radiation from the
Big Bang by its image of the microwave radiation. The patterns imprinted on
this radiation reflect the conditions set in motion a tiny fraction of a second
after the Big Bang. These slight fluctuations are the seeds from which galaxies
formed. Return and image of the WMAP and
include a brief description of the image. What are the values of the Age, Dark
energy (½), Dark Matter (½), percent of atoms (½), and HubbleÕs constant? (Beware
these results are 5 years old and have been updated by very similar new results):
http://antwrp.gsfc.nasa.gov/apod/ap040711.html
6.
The Sloan Digital Sky Survey (SDSS) is measuring the distances to over one
million galaxies. Return an image of the survey. Include a brief description of
the image. What are the values of the Age, Dark energy (½), Dark Matter (½),
percent of atoms (½), and HubbleÕs constant that are needed to explain the
distribution? Notice these results agree very well with the results from the
WMAP.