The Big Bang, Dark Matter and Dark Energy
The Universe is expanding, but how did it begin, and why can we see only a fraction of it? Weigh the Big Bang against the Steady State theory, meet the evidence that settled it, and explore the dark matter and dark energy that fill the cosmos.
Revise this, the fun way
Play it interactively, earn XP and build a streak, free.
Start revising freeWhat you'll cover
How did the Universe begin? 🌌
Redshift shows that galaxies are rushing apart: the Universe is **expanding**. Rewind that expansion and everything was once packed together. So how did it all begin? This module weighs two theories, meets the **evidence** that settled the question, and explores the **dark matter** and **dark energy** that make up most of the cosmos.
Two theories of the Universe ⚖️
Both theories were built to explain the **expanding Universe**, but they disagree about its beginning. Evidence has since made the Big Bang the accepted theory.
A shared starting point 🎈
The Big Bang and Steady State theories were both built to explain which observation?
- That the Universe is expanding
- That the Sun rises in the east
- That the Moon shows phases
- That stars appear to twinkle
The evidence, in four words 🔑
Four observations point to the Big Bang:
Match each observation to what it shows 🔗
- The CMB
- Quasars
- The Hubble Deep Field
- CMB ripples
- A cooled afterglow predicted only by the Big Bang
- Bright active galaxies seen only in the early Universe
- Thousands of distant young galaxies in one small image
- Tiny variations mapped by WMAP and Planck
Which are Big Bang evidence? ✅
Select the TWO observations that provide evidence for the Big Bang.
- A microwave afterglow coming from every direction
- Quasars found only in the distant, early Universe
- The daily rising and setting of the Sun
- The monthly phases of the Moon
The clinching evidence: the CMB 📡
The Big Bang predicts a faint glow left over from when the young Universe cooled. It is found coming from **every direction** as microwaves, at about **2.7 K** above absolute zero. The Steady State theory predicts **no** such afterglow, so the cosmic microwave background is the strongest single piece of evidence for the Big Bang.
The history of the Universe 🕰️
An interactive activity.
Cosmology in words 🧩
The _____ theory says the Universe began about 13.8 billion years ago and has expanded ever since. Its strongest evidence is the cosmic microwave _____, a faint glow from every direction. Most of the cosmos is invisible: unseen dark _____ is felt only through gravity, while dark _____ drives the expansion to speed up. Neither can be seen because they give out no _____.
Finding the invisible 🌑
Dark matter gives out no light, so how do astronomers know it is there?
- From its gravitational pull on stars and galaxies
- From the light it shines into telescopes
- From the sound it makes in space
- From radio messages it sends out
Match each part of the cosmos to what it is 🥧
- Ordinary matter
- Dark matter
- Dark energy
- The CMB
- Stars, planets and gas, only a small fraction of the whole
- Unseen mass known only from its gravity
- The influence making the expansion accelerate
- Leftover radiation from the early Universe
Spot the true statements 🖍️
An interactive activity.
What best explains it? 🧭
An interactive activity.
Evidence and the dark Universe ✍️
An interactive activity.