Physics GCSE: The Big Bang and red shift

Jon Chase explains the scale of the solar system and universe using simple demonstrations at a shopping centre and race track.

He explains the Doppler effect and introduces red-shift and cosmic microwave background radiation, which provide evidence for an expanding universe.

This short film is from the BBC series, Space Science Bites.

Teacher Notes

Use this short film as an introduction to a Doppler effect demonstration using a buzzer swung around on a piece of cord.

Discuss everyday examples of Doppler effect - such as the pitch change as a vehicle passes. Apparent shift in frequency could be investigated using a moving sound source and data logger.

This could be related to applications including radar and echocardiograms.

Discuss in more detail what redshift is: The ratio of velocity of a galaxy to the velocity of light.

As an expanding universe demonstration students could stick dots on an uninflated balloon and measure change in separation distance at different stages as the balloon is inflated.

Students should look at how the rate of increase in distance between spots is different depending on the spots' original positions.

This can be related to the different recession velocities of different galaxies based on their distance from us.

This can be related to Hubble's law, which allows us to estimate the age of the universe.

Following this, students could prepare a poster to explain evidence for the Big Bang.

Curriculum Notes

This short film will be relevant for teaching physics.

This topic appears in OCR, Edexcel, AQA, WJEC KS4/GCSE in England and Wales, CCEA GCSE in Northern Ireland and SQA National 4/5 in Scotland.

More from Space Science Bites:

Gravity on Earth and in space
The life cycle of stars
Nuclear fusion in stars
Spectroscopy and the composition of stars
Waves and communication