Space, as the old saying goes, is what stops everything from being in the same place. Empty space is actually much busier than that; and from the point of view of modern physics, not empty at all. One of the evidences of this is the Casimir Effect, illustrated in this striking microphotograph on the Astronomy Picture of the Day website.

The history of the effect is curious. It is nearly, though not exactly, the case that, as the APotD website says, Hendrik Casimir discovered the effect while studying the properties of mayonnaise. (Here’s the story.)

You never know where pure research will lead.