The title is about a couple of related formulas that set the precedent for a hypotheses that defragmented hard drives are "greener". P = W / t where W = F * Δs The first formula is defined as Power is equal to Work divided by Time. The second formula define Works as equal to Force multiplied by Displacement (change of physical location). So what does all this math mean? In a hard disk drive, power is used to alter magnetic forces and move an actuator arm back and forth across a spinning platter. This is often summarized by saying that work is equal to the force acting on an object times its displacement (how far the object moves while the force acts on it). Note that only motion that is along the same axis as the force "counts", however; motion in the same direction as force gives positive work, and motion in the opposite direction gives negative work, while motion perpendicular to the force yields zero work. An analogy: Let's say you are making a PB&J sandwich. The parts you need are scattered around the kitchen (a fragmented sandwich). The bread is in a bread basket on a kitchen counter, the peanut butter is in the pantry and the jelly was opened last week, so its in the fridge. Your assembly station is a fourth location - a kitchen island. To pick up all the fragments required to make your sandwich you have to move across the kitchen in multiple actions. But, what if the parts to Lunch were all unopened and sitting next to each other in the pantry - your jar of jelly, a fresh loaf of bread, and a new jar of peanut butter. Assembly your meal would be much faster, and save you the energy/calories of hoofing around the kitchen. That said, the fat in the peanut butter and the sugar in the jelly will certainly make up for the movement - but that's off the point. On your PC/Server, file fragmentation means that more electrical power is required to spin the hard drive around and more the actuator arm back and forth across the disk. OK you say, but I'm a few pounds overweight and could use the extra few steps. I have two suggestions on that: 1. eat an apple instead, or 2. your computer isn't pudgy, it really doesn't need to be exercised to stay young and fresh.