Deceptively simple bubbles float on complex science
Tom Noddy blows bubbles that seem to defy the laws of physics.
Some are shaped like cubes, others like dodecahedrons. The most complex ones even impress scientists and mathematicians.
But you don’t have to be the world-famous “Bubble Guy” – or be able to pronounce dodecahedron – to have fun making fleeting, floating creations from soap and water.
“People ask me to teach them how to do what I’m doing,” says Noddy, a Santa Cruz, Calif., resident who travels the globe with his “Bubble Magic” act. “Just watch what I’m doing. I’m not a magician; I’m not hiding anything.
“The best advice I can give is to just watch them. Blow a bubble and hold it in good light and watch it. … Just the effort to hold it up would teach you the skill.”
It seems simple enough. You just dip a plastic wand into some bubble solution, blow gently and out float a slew of iridescent spheres.
But what’s going on inside those airy playthings? Have you ever wondered how they work? Why they seem to reflect rainbows? Why they’re always round?
We consulted Noddy and a few other expert sources to break down the science of bubbles. Here are some highlights and interesting facts.
On the bubble
¢ Water already has a “skin,” or surface tension. You can see evidence of it if you fill a cup with the liquid and gently lower a paper clip onto the surface, says Jim McParland, a Kansas University graduate student in chemistry. The clip will float.
Adding soap decreases the tension by about one-third – weak enough to blow a bubble that will stay intact for a few moments.
¢ Surface tension is also responsible for making bubbles spherical. The tension pulls the water molecules into the tightest possible grouping; a sphere has the smallest possible surface area for a given volume.
Of course it’s fragile enough to be distorted by air currents, so it elongates when you first blow it. But once it leaves the wand, it quickly rounds off.
¢ Bubbles’ propensity to find minimum surface areas has intrigued scientists and mathematicians for centuries. More recently, architects and engineers have begun studying them, too. German architect Frei Otto scrutinized bubble films to build the tentlike roofs for the 1972 Munich Olympic Games stadium.
¢ When blowing a bubble, as soon as it becomes more than 3 1/7 times the length of its diameter, it forms a waist and splits off, Noddy says. So if you want a bigger bubble, you need a bigger wand.
¢ Although isolated bubbles form spheres, bubbles that join together distort a bit because it’s more efficient for them to share a common wall. If a third bubble joins the party, the bubbles always join at a trio of equal 120-degree angles. This holds true even in huge masses of soap suds, which, if you study them for a while, look like hundreds of hexagons joined together – just like the honeycomb in a beehive.
¢ Colors in soap bubbles are caused by light wave interference. Some waves are reflected off a bubble’s surface, while others enter the soap film and come back out after being reflected back and forth between the two surfaces. The colors change as the bubble thins; and when the bubble is about to pop, no reflection is visible at all.
Tricks of the trade
Noddy performs bubble “tricks,” such as combining two bubbles into one, blowing a long string of bubbles that look like a caterpillar and blowing a structure of bubbles with a series of tiny bubbles around its center that can be rotated to look like a carousel.
He has blown bubble masses with 32 faces. His biggest bubble was 10 feet in diameter (a drop in the bucket compared to the Guinness record 105-foot-long bubble).
Noddy says high humidity is crucial for bubble longevity, a fact he benefited from during a recent performance in Houston.
“The people were so miserable,” he says. “But the bubbles were so good.”
His best tip: Keep everything wet.
“If it’s wet, it won’t break,” Noddy says. “If your finger is wet, put your finger inside. If a knife is wet, put the knife inside.”
There’s no secret concoction behind his years of bubble-blowing success. Noddy just recommends the cheap bubble solution you can buy at any store.
He must be onto something. David Letterman featured him on “The Late Show” in February. The act went off without a hitch – despite an intense wind blowing over his shoulder from the air conditioner.
“I determined that I was going to accomplish each of the tricks,” he says, “and not let the audience know that I was fighting for my life on national television.”