Upper limit: a US Navy F/A-18 travelling near the speed of sound in air. The white halo comprises water droplets that have condensed from the air because of the sudden drop in pressure behind the ...

At a fundamental level, our Universe is made of particles, forces, interactions, and the fabric of space and time. Spacetime forms the ever-evolving stage on which the play of the cosmos unfolds, ...

In 2002, Duff, Okun, and Veneziano published an intriguing paper exposing their divergent views on the number of fundamental constants 1. Although this paper has attracted considerable attention, no ...