When I was a kid, I spent endless fascinating hours with my dad in the garage of our southwest Detroit home. The floor-to-ceiling shelves were crammed with boxes of spare parts and electric motors. On the floor and the workbench were large and small tools, acetylene tanks, a grinder, a drill press, and a lathe. My dad was a heating and air-conditioning serviceman, and he loved explaining and showing me how things work: things like his Triplett electrical tester. This black box, with dials, gauges, wires, and switches, looked to my 9-year-old eyes like some exotic scientific instrument from the future