• Size of universe: due to expansion, can see photons from galaxies currently beyond Hubble distance
• Dark energy: acts to accelerate expansion of universe
• Parallel universes: might have many bubble universes, perhaps with differing physical laws
• Wormholes: Conduit between two locations in spacetime; might permit rapid travel, white holes, etc

• Hubble distance: distance at which recession velocity due to expansion of space is equal to speed of light
• Cosmological constant: simplest theory of dark energy; vacuum energy with negative pressure
• Quintessence: Dark energy that can vary in strength in space and time; several possible varieties
• Chaotic eternal inflation: Decay of false vacuum occurs locally, can create true vacuum bubble universe
• Many worlds interpretation: Controversial quantum mechanics idea that postulates universes branch to cover all possibilities

NASA's Cassini orbiter is sweeping past Saturn's icy moon Enceladus today to photograph geyser-like eruptions from the Southern Hemisphere. The hope is to find signs of the building blocks of life: NASA has pegged Enceladus as one of the most likely places in the Solar System (along with Mars and another of Saturn's moons, Titan) to be able to support extraterrestrial life.

On a flyby earlier this year, the Cassini spacecraft detected organic chemicals like methane and propane in the contents spewing out of the moon's interior. Such compounds have also been found in comets' tails and just recently on Titan.