The video explains that sound cannot be heard in space because it is a vacuum, lacking the molecules needed for sound waves to travel. On Earth, sound travels through air molecules, and it can also move through liquids and solids. In space, the absence of a medium means sound waves cannot propagate, so no one can hear you scream.

Why can't people hear you scream in space?

What is the medium through which sound travels on Earth?

How do sound waves behave in gases, liquids, and solids?

Explain what is meant by a vacuum in the context of space.

What happens to sound waves in the vacuum of space?