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 ...

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 ...

Have you ever bent down to a quiet pond or peered into an unruffled bucket of water and seen your face looking back at you? This sort of everyday experience sometimes seems almost magical, especially ...