UNIVERSE | SCIENCE | TECHNOLOGY on Instagram: "When a hammer strikes a metal bar, it doesn’t just create a sound — it launches vibrations that travel through the metal at incredible speed. These vibrations are mechanical waves, carrying energy from the point of impact all the way through the bar. As the metal particles start compressing and expanding, they pass the energy forward like a rapid chain reaction. Your ears hear this as sound, but inside the metal, a hidden world of wave motion is hap