This article was taken from the February 2014 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
The Dr Seuss story Bartholomew and the Oobleck features a mysterious substance that rains down as a liquid but turns into a solid as it hits the ground. Real-world oobleck, named after the sticky menace from the children's book, is a non-Newtonian fluid that anyone can make at home.
Unlike water, honey or oil, its viscosity, or resistance to change, depends upon what you do to it. Slowly dip a finger into oobleck and it will feel like a goopy, wet pudding. Smack it and it will hit your hand like a solid. "As far as science that anyone can do, oobleck is easy, inexpensive and totally safe," says Noah Podolefsky, a physicist at the University of Colorado Boulder. "It's a fun thing to make for both kids and adults."
Create a suspension
Oobleck is cornflour and water. Start with one part water in a bowl. Slowly add 1.5 to two parts cornflour, stirring constantly.
Starch particles become suspended in water -- but too much water will create liquid. "You need the tipping point, at the non-Newtonian threshold," says Podolefsky.
Add a splash of colour
You can alter the oobleck's white hue by adding food colouring.
This addition will not change the oobleck's physical properties, Podolefsky says, but will just "make it look cooler". Go with green to imitate the classic Dr Seuss oobleck, or try another colour of your choosing.
Experiment with it
You can now explore your creation's non-Newtonian behaviours. Hold it in your hand and let it drip through your fingers. Make it into a ball and bounce it. See what happens if you hit it with a hammer.
Put it on top of greaseproof paper on a subwoofer and see it writhe.
Make a giant batch of oobleck and fill a paddling pool with it.
You can run across the substance's surface as if it were a solid, or jump up and down on the springy substance. Stop running, however, and you will sink into the oobleck bog as if it were quicksand.