Dark Energy

The accelerating universe

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Distant supernovae revealed in 1998 that cosmic expansion is accelerating.
• The cause is called dark energy: about 68% of the universe’s energy.
• A cosmological constant grows in importance as matter thins out.

Steps

1. Speeding up
2. The cosmic budget
3. A constant energy
4. The changeover
5. With and without dark energy
6. The worst prediction