• I can describe the Big Bang • I can describe the evidence for the Big Bang

1. The Big Bang
How did it all start?

2. Learning Objectives
I can describe the Big Bang
I can describe the evidence for the Big Bang

3. Recap from Last Lesson
The Universe is expanding!
We can see that because the galaxies are
moving apart
What can that mean?

4. What is Science??
Science takes observations and tries to
explain them
Science makes predictions
Science deals with “how” and not “why”

5. Before the Big Bang
Until the 1960s, most scientists believed in
The Steady State theory
This was the idea that the galaxies were
being pushed apart by matter leaking into
the Universe through holes.

6. Cosmic
Background
Radiation
Two telephone technicians had
made a microwave
communication system
There was interference in the
signal

7. Interference

8. Bird poo

9. Nobel Prize for Physics

10. No one could explain this background
radiation with the Steady State Theory
The radiation might be left over from a huge
explosion a long time ago (it’s a bit like being
able to feel the flame throwers at a
Slipknot concert from the side of the stage)

12. If the universe were created in a Big Bang
then we can make predictions
The intense radiation would have got
stretched into microwave frequencies by
the expansion of the universe
The radiation would be more or less the
same everywhere you looked
Outer space would be several degrees
above “absolute zero”