A science museum shows an animation of the Universe based on either the Big Bang theory or the Steady State theory. When the animation is played in reverse, the galaxies move closer together and some matter disappears, but the average density shown stays the same throughout.
Which identifies the theory and explains why matter disappears in the reversed animation?
Steady State; matter is destroyed when the galaxies move together and collide.
Big Bang; matter is destroyed when the galaxies move together and collide.
Steady State; matter that was created as space expanded is taken away again.
Big Bang; matter that was created as space expanded is taken away again.
94 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift, covering 7.2.1 Big Bang and Steady State theories, 7.2.2 Evidence for the Big Bang, 7.2.3 The Doppler effect and red-shift, 7.2.4 Red-shift as evidence for an expanding Universe, and 7.2.5 The CMB and the accepted model. Each one has a worked solution and a mark scheme showing where the marks go.