Ask Dr. Universe

Can you hear in space? Asked by a curious reader.

Dear curious reader,

Your question reminds me of an experiment: You put a ringing alarm clock in a jar and use a hose to slowly suck out all the air. As the air escapes, the ringing gets quieter until there’s no sound at all.

The inside of the jar becomes what scientists call a vacuum. It’s empty. Just like space.

Despite any zooms and explosions you may have heard in movies about outer space, sound actually can’t travel through empty space. That’s why on the moon, where there is no air, astronauts have to use radios to talk with each other.

Bu...