Concept
Dark Energy
The mysterious force accelerating the universe.
Discovered in 1998 when distant supernovae revealed cosmic expansion is speeding up, not slowing. Its nature remains one of the biggest open questions in physics.
See also
Gravity
The force that shapes the universe.
Redshift & Hubble's Law
The fingerprint of an expanding universe.
Baryon Acoustic Oscillations
A standard ruler frozen into the early universe.
Reionization Epoch
When the first stars and galaxies relit the universe.
Cosmic Dark Ages
The long pre-starlight era of the universe.
Big Freeze
A possible cold, dark final fate of the universe.