Hubble’s Law and the age of the Universe
The American astronomer Edwin Hubble studied distant objects in the Universe the realised that the further away from Earth they were, the faster they seemed to be moving. This relationship became known as Hubble’s Law and can be stated as:
v = H x d
where v is the velocity of a distant galaxy
d is the distance of the galaxy from Earth
H is the Hubble constant
The Hubble constant is actually a measure of how fast the universe is expanding. Since velocity is normally equal to distance / time, H in Hubble’s Law above must be 1/t and so if it is assumed that the expansion of the Universe has been uniform, and that the value of H hasn’t changed, then the age of the universe can easily be calculated by t = 1/H
The data below comes from the Hubble Space Telescope Key Project team. It shows very precise measurements of distance d and velocity v.
· On graph paper or in an excel spreadsheet, graph this data, with distance on the x-axis and velocity on the y-axis.
· Draw a line of best fit (it should pass through the origin) and evaluate the gradient. This will be your estimate of the value of the Hubble constant, H.
Best fit value of H with unit = ____________________________
https://www.youtube.com/watch?v=orw4MuprHsY
Questions:
1. Calculate the age of the universe using your value for H. Note that you will need to show your working for the conversion of the units into billion years (109).
2. Hubble originally found a value for the constant of 530 in the same units as your graph. What does this value give for the age of the universe? Show your working.
3. In the 1950s, the famous astronomer Baade, more than halved Hubble’s original constant. What affect did this have on Hubble's value of the age of the universe?
https://assist.asta.edu.au/print/2624