Physics P1 (Origins of the Universe)

Big bang

The beginning of space, time, matter, energy, and of the expansion of the universe. Astronomers have even detected a cosmic microwave background radiation, CMBR, that is thought to be the heat left over from the original explosion.

Doppler effect

When a source moves towards an observer, the observed wavelength decreases and the frequency increases. The waves would arrive more bunched together towards you so the sound would have a shorter wave length and a higher pitch.

When a source moves away from an observer…