A psychologist wants to know the difference (psychologically speaking) between an engineer, a physicist, and a mathmatician. [sub][sup](I’ve got to learn some jokes that are easier to spell.)[/sup][/sub]
He gets one of each to volunteer, and puts each one in a separate bedroom.
After the subjects have all gone to sleep, the psychologist sneaks into the engineer’s room and sets the trash in the wastebasket on fire. He leaves the room, makes a noise to wake the engineer, and watches the results on closed-circuit TV.
The engineer wakes up and sees the fire. There is a pitcher of water on the bedside table, and the engineer pours all of the water into the wastebasket. Then he takes the wastebasket into the connecting bathroom, flushes the ashes down the toilet, and leaves the wastebasket upside down in the tub. He returns to the bedroom, braces a chair under the doorknob of the door to the hall so no one can get in to start another fire, gets back in bed, and goes to sleep.
The next experimental subject is the physicist. When he sees the fire in his wastebasket and the pitcher of water, he scribbles a few calculations on the back of an envelope. Then he pours exactly enough water in the wastebasket to put out the fire. He sees that it worked, smiles, gets back in bed, and goes back to sleep.
Lastly, the psychologist starts a fire in the mathematician’s room. When the mathematician wakes up, he sees the fire, sees the water, and does a quick calculation in his head. Then he says to himself, “A solution exists,” rolls over, and goes back to sleep.