Visions 19: Dark energy
A mysterious repulsive force seems to dominate the Cosmos.
In 1998, astronomers made a shocking discovery that has forced them to re-think their ideas about the nature of the Cosmos. Surveys of exploding stars – supernovae – in distant galaxies indicated that they were much further away than expected.
We know that the Universe has been expanding ever since its birth in the Big Bang, but the new observations suggested that this expansion was accelerating, starting about 6 billion years ago.
This was not what cosmologists wanted to hear; they had developed a robust description of how the Universe has evolved into the galaxies and clusters of galaxies we see today.
Visions 19: Dark energy (PDF, 628 KB)