There’s a science convention, and three scientists are in hotel rooms adjacent to one another. One is a chemist, another is a physicist, and the third is a mathematician.

Once they all go to bed, a fire breaks out in the chemist’s room. He wakes up, sees the fire, runs to get the ice bucket, runs to fill it with water, and then douses the flames. With the fire extinguished, he goes back to bed.

Then a fire roars to life in the physicist’s room! He wakes up, sits down at a table and figures out how much water he’ll need to extinguish the fire, runs to get a huge Erlenmeyer flask, measures the water, then douses the flames. With the fire extinguished, he goes back to bed.

Another fire erupts in the mathematician’s room. The mathematician furiously scribbles on pages and pages, figuring out if it would even be possible to kill the flames, and if so exactly how much water would be required. After finishing a few proofs, he stands up, shouts “There is a solution!” and goes back to bed.