Sound needs a medium (solid, liquid, or gas) to travel. Space is a vacuum, lacking the matter to carry sound waves. No sound in space means no echoes. While a near-perfect vacuum, some sounds can be ...

That now classic tagline (from Alien, one of the greatest science-fiction horror movies ever made) hinges on a big assumption that most of us broadly make: space is empty. And it is—mostly. But there ...

We say a message is incoherent when we can't make it out, or when it doesn't make sense. A scribbled note, a drunken argument or a conversation taking place five tables down in a crowded cafe might ...

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. In 1987, a group of ...