Girls and Boys

In the high school gym, all the girls were lined up against one wall, and all the boys against the opposite wall. Then, every 10 seconds, they walked toward each other until they were half the previous distance apart. A mathematician, a physicist, and an engineer were asked, "When will the girls and boys meet?"
The mathematician answered, "never."
The physicist answered, "In an infinite amount of time."
The engineer answered, "Well, in about two minutes, they'll be close enough for all practical purposes."