Science
What is Dark energy?
Dark energy is a mysterious force thought to make up most of the universe and to be driving its expansion to accelerate. We can't see or directly detect it, but its effect — pushing galaxies apart ever faster — is measurable across the cosmos.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains dark energy.
Key things to understand
- 1It appears to make up roughly 68% of the universe.
- 2It acts like a repulsive force, accelerating cosmic expansion.
- 3It was discovered in 1998 from distant supernova observations.
- 4Its true nature is one of the biggest mysteries in physics.
- 5It's different from dark matter, which pulls things together.
Frequently asked questions
- What is dark energy?
- An unknown form of energy filling space that appears to push the universe apart, causing its expansion to speed up over time.
- How do we know dark energy exists?
- Observations of distant exploding stars showed the universe's expansion is accelerating, which requires some repulsive energy to explain.
- What's the difference between dark energy and dark matter?
- Dark matter's gravity pulls things together; dark energy does the opposite, pushing space apart and accelerating expansion.