A World of Amazement

8 A World of Amazement There is a loud noise coming from the top of the auditorium hall at St. Paul High School. Students are screaming, clapping and laughing. What's going on? It's a science show being presented by Professor LeBlanc from a prestigious university. Two volunteers are called up to the front. The professor hands them each a metal hemisphere with a handle. He then lines up the two hemispheres, edge to edge, making one complete metal sphere. On one of the half spheres, there is a valve. His assistant connects the valve to a pump and turns the pump on for a few seconds to get the air out of the ball. Then, he turns off the valve. The two volunteers are asked to pull the two halves to separate them. Cheered on by the crowd, the two students try as hard as they can, but the ball will not separate. More students are added to each side. The sound of cheers becomes even louder. The two sides pull and pull, like in a tug of war, but still they have no success.

" This demonstration, " the professor explains, “ shows how much air pressure is acting on us all the time. Think about that. Isn't it amazing?" Then, the professor starts his “ Cold War" show. Holding a celery stem and a few carrots, he dips the vegetables into some liquid nitrogen. Nitrogen is in our air all the time as a gas. But when its temperature drops to -200°C, it becomes liquid. When the professor takes the vegetables out of the liquid, he smashes them on the floor. The vegetables break into small pieces with little bits flying everywhere! The liquid nitrogen makes the vegetables fragile like glass. As the demonstration continues, the show becomes even more exciting. He chills his audience with a -78°C blizzard. He transforms soggy frozen cigars into torches and he fires electromagnetic cannons that shoot smoke rings at the audience. The crowd goes wild. “ That's cool! " one kid yells. “ I wish my parents had come to the show, " shouts another. The students really enjoy the show and they are eager to learn more about physics.