In a 2002 paper, Laser Elevator: Momentum Transfer Using an Optical Resonator, Thomas R. Meyer et. al. talk about a neat way to get a lot more speed out of light reflection than with a regular solar s...In a 2002 paper, Laser Elevator: Momentum Transfer Using an Optical Resonator, Thomas R. Meyer et. al. talk about a neat way to get a lot more speed out of light reflection than with a regular solar sail. The basic physics are pretty simple, and it’s a fun subject to think about. When a photon hits a solar sail, it gives the sail momentum.