Saturday, June 22, 2013

How a Physics Diagram Was Named After a Penguin

June 21, 2013

In 1977 John Ellis made a bet with a student named Melissa Franklin at a bar. “If you lose this game of darts,” Franklin said, “you have to use the word ‘penguin’ in your next paper.” Ellis took the bet, and lost. The result can be seen in physics classrooms all over the world: the penguin diagram. Here’s what it looks like:

Image: Quilbert
Symmetry Magazine explains the image:
Physicists represent particle decay paths in shorthand by making drawings called Feynman diagrams. A Feynman diagram is series of squiggles, lines, loops and letters that track quantum processes. The diagrams are named after their inventor, theorist and Nobel Laureate Richard Feynman.

In the diagram of the bottom quark decay, the virtual particles appear as a loop and a series of squiggles. The final drawing almost resembles a bird with a head, a round, white belly and two feet.
Why did Franklin choose a penguin? Apparently it has to do with a joke that had nothing to do with physics at all. It goes like this:
A truck driver is delivering two penguins to a new zoo when he runs over a nail in the road. He manages to flag down a passing motorist.
“Hey there,” says the truck driver. “I’ve got a flat, but I need to get these penguins to the zoo ASAP. Will you please take them while I fix this problem?”
“Of course, no worries,” says the motorist. “Happy to do it. I love penguins.”
So the two penguins crawl into the passenger seat, and off they go.
Well, it takes a little while, but the truck driver gets his tire fixed up. He drives into town headed for the zoo, but when he passes by the cinema, who should he see walking out the door but the motorist with the two penguins in tow.
“Woah there,” he calls out. “I thought I asked you to take them to the zoo!”
“Oh yes, you did,” says the motorist. “But we had a bit of change left over, so we decided to take in a movie, too!’
Franklin is now the chair of the Harvard University Department of Physics, where she is not in charge of any penguins.


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