Sand is actually made up of lots of different things. When we look at it under the microscope, we can see cooled lava, coral, seashells, and other kinds of wonderful, colorful rocks.
If you add just the right amount of water to sand, it transforms into a pretty good material for shaping towers, walls, and spires for a sandcastle. At first, I thought the wet sand stuck together because of a chemical reaction. But it turns out this interplay of sand and water creates what scientists call a physical reaction.
That’s what I found out from my friend and physicist Lauren Barmore, a graduate researcher at Washington State University who is very curious about matter and how things work on our planet.
She explained that if you had two rocks and put a bit of water in the middle, the water would be attracted to the rocks and form a kind of liquid bridge between them. One property of water is that it doesn’t like to touch the air. Water would rather hang onto something else.