Specification
Point Necessary Understanding
16.1 Know galaxies outside the local group are redshifted
16.2 Understand the cause of redshift
16.3 Use the relationship between observed wavelength, velocity, and the speed of light
16.4 Understand the evidence to confirm the discovery of the expanding universe
16.5 Be able to use Hubble’s Law
Understand the estimation of the age and size of the Universe using the value of the
16.6
Hubble constant
Understand how the expansion of the Universe supports both the Big Bang Theory
16.7
and Steady State Theory
, Know that observations of galaxies outside the Local Group show that light is shifted to longer
16.1
wavelengths (redshift)
16.2 Understand that redshift is caused by galaxies receding from us
[2]
Radiation emitted from a source moving away
causes the elongation in the wavelength – redshift.
Galaxies outside
If a galaxy is emitting radiation and is moving of our local
towards an observer, the wavelength of the group are
radiation is contracted – blueshift. receding from us
with increasing
The Doppler Effect for the universe is caused by
speed and thus
expansion of the universe and local changes in
are redshifted.
the gravitational field of galaxies.
, 16.1,2
What is the Doppler Effect?
How does a receding galaxy form an observe change the radiation
that observer will observe.
Explain how radiation can be red-shifted as opposed to blue-
shifted.
State which portions of our universe are red-shifted.