Can we turn back time? Ask a savvy physicist, and the answer will be “it depends.” Schemes for retrograde time travel abound but usually involve irreconcilable paradoxes and rely on outlandish ...

If you shine a light at a mirror, the beam is reflected inward to a central focal point, bouncing back toward you in a predictable manner—it’s a simple reflection of light, a spatial inversion. When a ...

We are surrounded by waves. tiny vibrational waves transport sound to our ears. Light waves stimulate the retinas of our eyes. Electromagnetic waves bring radio, television and endless streaming ...

Have you ever sat on the bottom of a swimming pool and pondered your watery ceiling? Most of the surface is a sheet of light blue, and you can't see through it, even though the water is clear. But ...

With walls and ceilings a long way away, often the most practical way to control the placement of a light source and the positioning of light, is to drop it into the exact position where it’s required ...