Orange juice, and fundamental physics, a la Rube

It’s one of the most vivid memories of my high school years. I’m dozing on my kitchen floor, surrounded by a debris of screwdrivers, scrap wood, ball bearings, nails, old cardboard boxes, springs, wood glue, wire hangers, and lots of duct tape. My dad nudges me in the side with his slippered foot. “It’s three o’clock in the morning,” he says. My cheek is squashed against the cool tile floor. I crack an eye open and see my nemesis: the golf ball that, in just a few hours, I’m supposed to somehow raise six feet in the air, in ten steps, for my physics final project.

Whom did I have to blame for my predicament? Not my physics teacher exactly, but rather a famous American cartoonist who never forgot the strange contraptions he saw in his engineering classes at UC Berkeley. After graduating in 1904, the engineer soon traded in his slide rule for a cartoonist’s pen, but his training inspired his most beloved cartoons and even earned him a spot in the dictionary:

Rube Goldberg’s signature drawings of hilariously baroque, hopelessly inefficient inventions drew their inspiration from engineering to poke fun at bureaucracy and irrationality. According to an article on Goldberg from UC Berkeley,

Goldberg gave credit for “one of the principal props of my career as a cartoonist” to an engineering professor, Freddy Slate. The professor had devised the Barodik to measure the earth’s weight with “a series of pipes and tubes and wires and chemical containers and springs and odd pieces of weird equipment which made it look like a dumping ground for outmoded dentists’ furnishings,” Goldberg wrote.

“Like the Barodik, my “Rube Goldberg” inventions are incongruous combinations of unrelated elements which cause a chain reaction that accomplishes something quite useless. It points up the human characteristic of doing things the hard way.”

But Goldberg’s cartoons have since moved in the other direction, inspiring the engineers and physicists he satirized. Not only do probably hundreds of physics teachers assign Rube Goldberg final projects to their students each year, the national Rube Goldberg Machine Contest at Purdue University celebrates engineering for engineering’s sake with ridiculous solutions to straightforward problems. First launched in 1949 by two engineering fraternities and later resurrected in the 1980s, the contest challenges high school- and college-age engineers-in-training to complete simple tasks like changing a lightbulb or assembling a hamburger in 20 steps or less. In 2007, Ferris State University won first place with this contraption that takes probably a hundred steps to squeeze a glass of orange juice (the action starts at 2:13):

If that tickled your fancy, check out the top ten best food-related Rube Goldberg machines and this top ten list.

Nothing compares to the fun of building a Rube Goldberg for yourself, but if you just don’t feel like digging out the wood glue and the duct tape, an online game called Dynamic Systems will amuse the inventor in you. The task is simple, and doesn’t change—get the ball bearing into the cup. But each level adds dominoes, springs, widgets and whirligigs to the challenge. I’m not sure if the game physics is perfectly accurate, but it’s a fun way to test out the conservation of energy.

A screen shot from Dynamic Systems, a Rube Goldberg video game.

Rube Goldberg may have found engineering more amusing than amazing, but his satirical inventions have some truth in them. Rube Goldberg machines powerfully demonstrate how energy is conserved, and can be converted from one form to another, potential to kinetic and back again. I also love how the machines often shift the scale of motion, from a tiny ball bearing falling down a shoot to a huge lever arm swinging.

They also make me think of particle detectors. Incredibly intricate and often several stories high, particle detectors like those at CERN depend on complicated, seemingly fragile sequences of physical phenomena to turn a fleeting spray of fundamental particles far too tiny to see into an electrical current and, finally, a bit of data. I won’t attempt to explain how ATLAS works, but take the humble photomultiplier, which is often found in larger particle detectors, as a small scale example:

Inside a photomultiplier.

When a photon hits the scintillating material, an electron in one of the atoms gets excited and then drops back down to its ground state, re-emitting a photon in the visible spectrum. This in turn hits the photocathode, causing an electron to fly out into the vacuum chamber of the photomultiplier thanks to the photoelectric effect. Each of the dynodes is set at a slightly higher voltage than the last, causing the electrons to accelerate a little more on their way, increasing their energy. This means that as the electrons hit a dynode, more and more electrons are produced. By the time you get to the end of the chamber, you’ve got enough electrons for a discernible jump in current, turning the tiny “bump” of the photon into something you can actually detect and quantify. And yet the process has so many steps, you might be tempted to call it Rube Goldberg. You would also have to say that, like the contraption for squeezing a glass of orange juice, it might be complicated, but it definitely works.

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