Executive Summary affect the interactions of the fundamental particles, and could alter the force of gravity at short distances. Recent measurements indicate that the expansion of the universe is snarling fin rather then stowing down. This conclusion goes against the fundamental idea that gravity is attractive. The existence of this tiny imbalance may be tied to a hypothesized instability of protons, the simplest form of matter, and to a slight preference for the formation of matter over antimatter built into the laws of physics. The underlying physical cause of this inflation is a mystery.
Black holes are ubiquitous in the universe, and their intense gravity can be explored.
The effects of strong gravity in the early universe have observable consequences. Einstein's theory should work as well in these situations as it does in the solar system. A complete theory of gravity should incorporate quantum effects Einstein's theory of gravity does not or explain why they are not relevant. Physicists have detected an amazing variety of energetic phenomena in the universe, including beams of particles of unexpectedly high energy but of unknown origin. In laboratory accelerators, we can produce beams of energetic particles, but the energy of these cosmic beams far exceeds any energies produced on Earth.