In the 1990s, Japan’s new bullet train faced a serious problem. At speeds of 300 km/h, every time it entered a tunnel, it created a loud sonic boom. The pressure waves were so powerful that nearby buildings shook. More than 100 engineers tried to solve it — and failed. Then one engineer noticed something incredible in nature. The kingfisher, a bird that dives into water at high speed… without making a splash. The secret was its long, narrow beak, which allows it to move smoothly between air and