This introduction covers The Universe is Running Away within Red Shift & Big Bang for GCSE Physics. Revise Red Shift & Big Bang in Space Physics for GCSE Physics with 13 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 1 of 14 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 1 of 14
Practice
13 questions
Recall
12 flashcards
🚀 The Universe is Running Away
In 1929, the American astronomer Edwin Hubble made a discovery that overturned everything scientists thought they knew about the universe. By carefully analysing the light from distant galaxies, he found that nearly every galaxy is moving away from us — and that the further away a galaxy is, the faster it is receding. The universe is not static. It is expanding.
Think of it like a balloon being inflated. Draw dots on the surface of the balloon to represent galaxies. As the balloon inflates, every dot moves away from every other dot — and dots that were further apart to begin with move apart faster. No single dot is at the centre; the expansion is happening everywhere, in all directions.
If you run this expansion backwards in time — like rewinding a film — all the galaxies come together at a single point. Go back far enough, about 13.8 billion years, and everything in the observable universe was compressed into an unimaginably hot, dense state. Then it expanded rapidly. This was the Big Bang — not an explosion in space, but the creation of space itself.