A vacuum can expand indefinitely

Empty space

Not only is it pretty intergalactic in space, it's also completely silent. If you were to fly into space, no one could hear you laughing. Why? This is because there is no air in space.

Space begins about 200 km above our earth. The layer of air that surrounds our planet ends there. Space is a vacuum, and such an empty space is called vacuum. Because sound does not move without air, you cannot hear anything in a vacuum.

A vacuum can also be created on earth. We tested it in the studio and pumped all the air out of an airtight glass case with the help of a vacuum pump. We put a loud ticking alarm clock and a radio microphone in the box.

We put the alarm clock on sand to insulate it, otherwise the box walls could transport sound waves. We also carefully attached the radio microphone with a thread and hung it in the box. Since there is air in the glass case, you can clearly hear the alarm clock ticking. But if you connect the vacuum pump to the box and turn it on, all air is withdrawn from the room and a vacuum is created. The ticking of the alarm clock can then no longer be heard. Ah!

However, space is not absolutely empty. There are tons of atoms and molecules between the stars and planets. People without spacesuits could not survive in space. We could not breathe and our blood would start to boil under the pressure conditions of the vacuum in space if an internal pressure were not generated in the suit.

By the way: Because no sunlight is scattered in space without air, it is not blue like our sky, but black with small, shining star points.