Cosmic Accelerants

• cosmological constant
• dark energy

Expansion History

• recently: accleration, but in past deceleration
• the cosmic coincidence problem

Dark Energy

• dark energy solutions to coincidence
• dark energy vs cosmo constant
• cosmo threat: the big rip

Unmaksing Dark Energy

• Ground-based observations: Dark Energy Survey, LSST
• Space-based observations: Euclid