#### Version 1

A mad scientist who kidnapped three colleagues, an engineer, a physicist, and a mathematician, and locked each of them in seperate cells with plenty of canned food and water but no can opener.

A month later, returning, the mad scientist went to the engineer’s cell and found it long empty. The engineer had constructed a can opener from pocket trash, used aluminum shavings and dried sugar to make an explosive, and escaped.

The physicist had worked out the angle necessary to knock the lids off the tin cans by throwing them against the wall. She was developing a good pitching arm and a new quantum theory.

The mathematician had stacked the unopened cans into a surprising solution to the kissing problem; his desiccated corpse was propped calmly against a wall, and this was inscribed on the floor in blood:

Theorem: If I can open these cans, the I shall not die.

Proof. Assume the opposite…

#### Version 2

A mathematician, an engineer, and a chemist were walking down the road when they saw a pile of cans of beer. Unfortunately, they were the old-fashioned cans that do not have the tab at the top. One of them proposed that they split up and find can openers.

The chemist went to his lab and concocted a chemical solution that dissolves the can top in an instant and evaporates the next instant so that the beer inside is not affected. The engineer went to his workshop and created a new HyperOpener that can open 25 cans per second.They went back to the pile with their inventions and found the mathematician finishing the last can of beer. “How did you manage that?” they asked in astonishment.

The mathematician answered, “Oh, well, I assumed they were open and went from there.”

#### Version 3

Psychologists subject an engineer, a physicist, and a topologist to an experiment: Each of them is locked in a room for a week — hungry, with a single can of tuna fish but without an opener; all they have is pencil and paper.

At the end of the day, the psychologists open the engineer’s room first. Pencil and paper are unused, but the walls of the room are covered with dents. The engineer is sitting on the floor and eating from the open can: He threw it against the walls until it cracked open.

The physicist is next. The paper is covered with formulas, there is one dent in the wall, and the physicist is eating, too. He calculated how exactly to throw the can against the wall, so that it would crack open.

When the psychologists open the topologists’s room, the paper is also full of formulas, the can is still closed, and the mathematician has disappeared. But there are strange noises coming from inside the can…

Someone gets an opener and opens the can. The topologist, covered in tuna fish, crawls out. “Dammit! I got a sign wrong again…”