Why Is Space Not Actually Empty?

You might think space is just a big, empty box where stars float around. But if you took all the air out of your room and sent yourself into deep space, you would still not be in total emptiness. There are tiny specks of dust, slow-moving gas clouds, and even invisible bursts of energy popping in and out of existence everywhere.

Imagine a swimming pool that looks perfectly calm on the surface. If you look closer, there are fish swimming underneath. Space is like that pool. It has interstellar dust which is like fine sand. It also has hydrogen gas, which is very light and spread out thinly.

The most surprising part is what scientists call quantum fluctuations. This means that even where there seems to be absolutely nothing, tiny bursts of energy appear and disappear in a flash. It is like the space itself is boiling with invisible activity. So when you look up at the night sky, remember that it is never truly quiet or empty.