One of the things I detested about being a little kid was that every time I thought of something really cool to do, I was invariably thwarted by my little brother shouting, “Mom! Kelvin's mixing rocket fuel in the bathtub again!” or “Mom! Kelvin's making a submarine out of the old refrigerator!”. Well, middle age has its drawbacks, but at least you can undertake a project like this without fear of getting nipped in the bud at the cry, “Mom! Kelvin's down in the basement bending spacetime!”. ...