All Subjects
      All Types




        Permitted Use

        Stream, Download and Share

        Part of Genius by Stephen Hawking
        4 Favorites

        Where Did the Universe Come From? Ch. 2: Doppler Shift | Genius by Stephen Hawking

        In this clip from Genius by Stephen Hawking watch the volunteers apply the Doppler effect to the expansion of the universe. By attaching a siren to a fast drag race car, the volunteers witness the Doppler effect in action. They learn that the frequency and wavelength of soundwaves changes depending on where the observer is positioned as the race car (source) goes past. In 1929, Edwin Hubble discovered that almost all the galaxies in the universe were moving away from us. He also discovered the further away a galaxy is the quicker it is moving. By applying the Doppler theory of sound to this concept, the volunteers learn how they can establish a frequency change in light. High frequency light appears blue and low frequency light appears red. So it is possible to work out the speed and direction a galaxy is travelling in by observing its colour.


        You must be logged in to use this feature

        Need an account?
        Register Now