A professor one day demonstrated to his class the power of an electro-magnet. He placed 2 lbs. of nails on a table with the wires of an electo-magnet under the table. When he flipped the switch, the nails came togehter and he was able to form the nails into various shapes as long as the current was on. When the current was cut, the nails fell back into a pile. This reminds us that as long
...