With speeds seven times the speed of sound, temperatures hotter than the sun and chemical reactions that rip apart air molecules, hypersonic flight sounds terrifying. But a professor and some students ...

The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At 20 °C (68 °F), the speed of sound in air is about 343 metres per second ...

Karen Hopkin: Bats rely on echolocation to navigate the night skies and to chase down and capture even erratically moving prey. But even more impressive than their aerial acrobatics are the mental ...

Editor’s Note: Sign up for Unlocking the World, CNN Travel’s weekly newsletter. Get the latest news in aviation, food and drink, where to stay and other travel developments. Savior of many a cramped ...