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Hubble’s Law: Measuring the Age of the Universe. Dr Lisa Jardine-Wright Cavendish Laboratory, University of Cambridge. Einstein 1915. General Theory of Relativity: Told astronomers that the Universe was either expanding or contracting depending on the amount of Mass and Energy in the Universe
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Hubble’s Law:Measuring the Age of the Universe Dr Lisa Jardine-Wright Cavendish Laboratory, University of Cambridge
Einstein 1915 • General Theory of Relativity: • Told astronomers that the Universe was either expanding or contracting depending on the amount of Mass and Energy in the Universe • Einstein didn’t like this idea so modified his theory to ensure that the Universe was static.
Experiment • Using cutting edge data and images we are going to reproduce Edwin Hubble’s observations. • To do this we need to measure the distance and velocity to a number of spiral galaxies and see if we observe a relation between these two quantities.
Part 2: Velocities • White light can be split into its component colours or wavelengths • Spectrum
Part 2: Velocities • How do we measure the velocities of distant galaxies? • Redshift - The astronomical Doppler effect
Part 2: Velocities • Different chemicals absorb and emit light of different colours or wavelengths.
Part 2: Velocities • The wavelength of the emission and absorption lines from elements in our galaxy are redshifteddue to their velocity away from us. • If we can measure how much they are shifted we can calculate their velocity λ0 = wavelength of line in the Lab, v = velocity of the galaxy and c = speed of light
Example • λ = 3962, λ0 = 3933.7, c = 3 x 105 km/s
Hubble’s Law Hubble's Law Velocity (km/s) Distance (Mpc)