Dark Matter Dark Energy

Observations of the universe's large-scale structure and the motion of galaxies indicate that the universe contains much more matter than we can see (dark matter, 27% of the universe) and an energy driving its accelerating expansion (dark energy, 68%). Only 5% of the universe is ordinary matter (atoms, the stuff we're made of). Dark matter and dark energy have been confirmed indirectly through many independent observations — but their nature remains completely unknown. Dark matter evidence: galaxy rotation curves (stars at the edges of galaxies rotate too fast for the visible mass to account for — something extra must be there); gravitational lensing; galaxy cluster collisions (Bullet Cluster shows visible matter and dark matter separating during a collision). Dark energy evidence: Type Ia supernova distance measurements showed galaxies are accelerating away from each other — requiring a repulsive energy in space. Current dark matter candidates: WIMPs, axions, primordial black holes. Dark matter detectors (LUX, PandaX) have found nothing yet.