LOGAN — A widespread belief among physicists nowadays is that modern science requires squadrons of scientists and wildly expensive equipment. Craig Wallace and Philo T. Farnsworth are putting the lie to all that. Wallace, a baby-faced tennis player fresh out of Spanish Fork High School, had almost the entire physics faculty of Utah State University hovering (and arguing) over an apparatus he had cobbled together from parts salvaged from junk yards and charity drops. The apparatus is nothing less than the sine qua non of modern science: a nuclear fusion reactor, based on the plans of Utah's...