1. IP1.32.3 Evidence for the Big Bang © Oxford University Press 2011 Evidence for the Big Bang

2. IP1.32.3 Evidence for the Big Bang © Oxford University Press 2011 The Big Bang  The Big Bang is the most widely recognised scientific theory on how the Universe began.  It states that the Universe began from a very small, very dense and very hot initial point.  It burst outwards in a great explosion, and all matter and space was created in the Big Bang.  It is even thought that this was the moment when time began.

3. IP1.32.3 Evidence for the Big Bang © Oxford University Press 2011 Evidence for the Big Bang – Red-shift  The first piece of evidence for the Big Bang is from data collected on red-shift.  Red-shift shows us that galaxies which are furthest away from us are moving faster than galaxies closer to us.  The galaxies are a bit like coloured sparks from an exploding firework. The sparks moving fastest travel the furthest.  If you could run time backward you would see the sparks all starting in one point. The same is true for galaxies.

4. IP1.32.3 Evidence for the Big Bang © Oxford University Press 2011 Evidence for the Big Bang – Cosmic microwave background radiation  In the 1960s two scientists called Wilson and Penzias noticed that a form of microwave radiation was affecting their readings.  The electromagnetic radiation was everywhere and is now called cosmic microwave background radiation (CMBR).  CMBR is explained as being heat left over from the Big Bang.  As the Universe exploded, it cooled and the radiation was stretched out. Today this radiation is in the microwave region of the electromagnetic spectrum.

5. IP1.32.3 Evidence for the Big Bang © Oxford University Press 2011 Unanswered questions  There are still a great number of unanswered questions in physics.  The scientific theories do not explain how or why the Universe began.  Recent observation suggests some very strange events at the edge of the Universe due to it not expanding in the way the Big Bang predicts.  Scientist have tried to come up with theories explaining these observations, including dark matter and dark energy.