Einstein for Duck Hunters

Albert and I labored together on a project near Walden Pond, chopping Abraham Lincoln's wife's family farm into a subdivision. Al was seventeen, already a graduate student at MIT, working on mentally mutating a basketball into a donut without piercing the skin, and on a set of formulas that would predict the motion of an ice cube when dropped into a hot skillet. I was twenty-two, healing from a hasty marriage.
Al piled the slash in clearings, to be burned in the fall. I was the chainsaw operator, hacking a road right-of-way through old-growth hardwoods that Mary Todd had climbed as a little girl. During our first lunch together, I asked Albert what he had been thinking about while he was dragging brush. He said that he spent the morning determining that all humans on the planet would fit in a cubic mile box, which when dropped into a Pacific trench would have less than a millimeter's impact on sea level. Cheery stuff. In an effort to change the subject, I asked about his family background.
Al's father was an Italian immigrant, a student of Tesla's electromagnetic theories, who worked through the 1940's as a technician in the Princeton University laboratories during Albert Einstein's tenure there. He named his first son after Einstein.
I confessed my ignorance of the theory of relativity, figuring Al must have a handle on some of it. A duck flew by, headed for Walden Pond. Albert launched into a synthesis between hunting ducks and applying Einstein's theories.............
Einstein believed that the measurements of length, time, motion, and mass are not absolute, but depend on the relative velocity of the observer. If a hunter is standing in a duck blind and trying to kill a duck that is flying past, the hunter must lead the duck, shoot in front of it, so the shotgun pellets and the duck arrive at the same place at the same time. If the hunter is moving faster than the duck, from the back of a jeep for instance, the hunter must shoot behind the duck.
A single shotgun pellet, sitting on a duck's head, will probably not kill the duck, but if we grant the pellet a little velocity relative to the duck's head, the pellet picks up energy, and, in some sense, mass, so that at enough velocity the pellet-duck collision is fatal, usually to the duck.
Not everything is relative in Einstein's duck blind. We need an absolute for the purpose measuring degrees of relativity. The speed of light remains constant independent of the motion of the observer. If a duck is flying toward us at half the speed of light, with a flashlight taped to its beak, the light from the flashlight is going l86,282 miles per second. If the duck is flying away from us and shines the beam back, the light is still traveling l86,282 miles per second. All this somehow meant that energy equals mass times the speed of light squared.
Late that fall, after I had taught Al about motorcycles and drugs and the smell of women, when the first snows fell, we torched the brush piles. We had stacked three of the largest on an ancient peat bog. The fires burned down into underground seams that smoldered for years, leaving much of the Todd estate useless for human housing.