I was reading Bill Bryson's "A Short History on Nearly Everything" today and came across a scientist I had never heard of before, but probably should have. Are you familiar with Thomas Midgley? This guy came up with a way to stop the "knock" in engines. He added lead to the fuel. Thanks to this brilliant idea we have about 625 times more lead in our system than people did 100 years ago. Thomas didn't stop there though. Next he improved on refrigerators by inventing chlorofluorocarbons, CFCs. I wonder if any one scientist has had a greater impact on the planet.