Redshift Hubble’s Law
Redshift - absorption spectra
Plot of intensity
From doppler effect From triangulation of movement of Earth
Increase in distance over time A B C
3 Galaxies A,B & C A B C
After time t A B C
A B C A B C Distance travelled
= H 0 d where Ho = 2·4 × 10 −18 s −1
1Parsec = light years
Edwin Hubble
Three astrophysicists are discussing the results of observations that show that all stars have their light frequencies decreased by a small amount – ‘red shift’ Professor Bubble “The red shift shows the stars are all moving away from our stationary Solar System” Doctor Toil “The red shift shows that we are moving away from the rest of the universe at high speed” Professor Trouble “The red shift shows the stars are moving away from each other”
Which viewpoint do you agree with and why? Why do you disagree with the other two or do you think no one is correct? What additional data from observations of starlight would allow confirmation? Professor Bubble “The red shift shows the stars are all moving away from our stationary Solar System” Doctor Toil “The red shift shows that we are moving away from the rest of the universe at high speed” Professor Trouble “The red shift shows the stars are moving away from each other”