Egon Orowan dislocation discovery (rug anecdote)

Origin of the dislocation concept in 1930s Hungary; Orowan watching a maid kick a dislocation across an oriental rug. Used to introduce the concept of dislocations as one-atom-row-at-a-time deformation.

Two guys came up with dislocations. One was Egon Orowan in Hungary. Orowan ended up in mechanical engineering over here at MIT. He was towards retirement when I came as a freshman, but he was still teaching a couple of courses. He learned about dislocations because he was at some academic institute in Budapest, and he had this big office, and it had a big oriental rug, and the rug was slightly shifted. The maid was cleaning, and she says, oh, the rug needs to be moved. He says, well let me help you, because it's a big heavy rug. And she says, no, I can do it. So she takes the rug and he just watches her, and here's the rug lying there, and she puts a dislocation in the rug, and she kicks it across the room. The rug moved about six inches. He looked at it and he thought, that's how metals deform. So a dislocation, you're breaking one row of atoms at a time, rather than a whole plane of atoms. The other guy was somebody in England — I can't remember who. They both independently came up with the concept of dislocations in the 1930s.

Hungarian cleaning lady, working in Orowan's office, moves a Persian rug across the floor by introducing a small fold and kicking it across the room. Orowan watches and recognizes the principle of an edge dislocation. Tom physically tears a sheet of paper to demonstrate.

Egon Orowan told the story of how he learned about a dislocation. [Tom tears a sheet from a pad of paper to demonstrate.] He had a very big office with a great big Persian rug. He was working in his office and the cleaning lady came in and noticed that the rug needed to be moved about three or four inches. He said, "I'll help you." She said, "No, I don't need any help." So he watched her. She put a little fold in the rug, like this, and she kicked it across the room, and when she was done the rug had moved a couple of inches. Orowan looked at this, and he thought about it some more.