I have a simple test that will determine whether you are a mathematician or a physicist. To take this test, you have to solve two problems. The problems are simple, and based on your solutions, I will be able to tell whether you are a mathematician or a physicist.

Problem 1: Before you is an ordinary gas stove (cooker, for you Brits). An empty pot is sitting on it. Nearby is a sink with one faucet that provides cold water. Your task is to boil water. How do you do it?

(Since nearly everyone solves this problem the same way, I will save time by providing the answer. You won't do this when you perform the test on your friends, however.)

Solution 1: Carry the pot to the sink and fill it full of cold water. Place the pot on the stove and turn on the burner. Wait for the water to boil.

Bravo! Now proceed with the second problem:

Problem 2: Before you is an ordinary gas stove. On it there is a pot full of cold water. Nearby is a sink with one faucet that provides cold water. Your task is to boil water. How do you do it?

(OK, most people solve this problem the same way, too, so I will provide the answer. You won't do this, of course…)

Solution 2A: Turn on the burner. Wait for the water to boil.

Aha! That proves you are a physicist. If you had been a mathematician, your solution would have been…

(Solution 2B will be provided after a suitable interval.)