Everyone knows Murphy's Law: Anything that can go wrong, will. I'm reminded of this law every time I choose a line at a store and notice the lines on either side of me always seem to move faster than the one I'm in. The question finally struck me: Was there really a Murphy, and what compelled him to lend his name to such a pessimistic axiom?
It turns out there really was a Murphy-Capt. Edward Murphy Jr., a development engineer at Edwards Air Force Base in Kern County, Calif. In the late 1940s, engineers wanted to determine how many Gs-where G is the force of gravity at sea level-a human body could withstand in a plane crash. At the time, conventional wisdom held that 18 Gs was the upper limit, and that forces stronger than that would crush every bone in a person's body.
Military aircraft were designed with this 18-G limit in mind, but some researchers believed the human body could withstand even more force. After all, pilot Chuck Yeager had broken the sound barrier safely two years earlier, even though naysayers predicted the speed would kill him or at least render him brain-damaged.
So the Air Force designed tests to measure the limits of human endurance to G-forces. Scientists mounted a rocket sled on a long railroad track. They planned to fire the sled down the track, then decelerate it in one second, mimicking the effects of an airplane crash. On the first test run with a dummy on board, the sled flew off the track and crashed in the desert. But after 30 more trial runs over the next six months, one brave volunteer was finally ready to strap himself in.
Col. John Paul Stapp had done his own calculations and concluded a body could withstand twice the 18-G limit that researchers hypothesized was safe. So in December 1947, he boarded the rocket sled and prepared for an adventure many thought would kill him. Instead, he successfully survived a run that produced 25 Gs.
Over the years Stapp did more runs at higher G-forces, until, in 1954, he was to make his most dangerous run: a run that would produce more than 40 Gs.
The engineers knew the test would take such a damaging toll on Stapp's body that they resolved to only run the test once. Naturally, they wanted everything to be flawless. Stapp was fitted with gauges and instruments all over his body to measure the forces.
Finally, the moment of truth arrived. Stapp boarded the sled, gave the thumbs-up, and was shot down the track at over 600 mph, then jolted to a stop in 1.4 seconds. It was the equivalent of driving into a brick wall at 120 mph. The forces were so strong, Stapp suffered severe retinal hemorrhage, two wrist fractures, multiple rib fractures and a collapsed lung. The researchers regretted putting him through such trauma, but at least the data they would gain would be so valuable that his suffering would not be in vain. The scientists rushed back to the lab, looked at the measurements from the dials and found-nothing. None of the gauges worked.
It turns out the gauges were all working properly, but a technician had installed them backwards, prompting Capt. Murphy to bellow, \If there are two ways of doing something, and one of them is wrong, someone will find a way to do it wrong!"" That statement has since morphed into what we recognize as Murphy's Law.
However, Murphy's Law isn't just a meaningless aphorism. Even today, engineers design products with Murphy's Law in mind. For example, think about when you try to plug a cord into a socket, but the plug doesn't go in. So you rotate the plug 180 degrees and it fits. That's because engineers have recognized there are two ways to plug it in-if they make the wrong option impossible to implement, people will only plug things in correctly.
That's the same reason an Ethernet cable is designed to be a little wider than a phone cord. Similarly, you can't insert a 3.5-inch floppy disk upside-down-well-designed engineering won't let you do it. For some reason, technology regressed with CD-ROMs that can be inserted upside-down.
Stapp endured the pain but Murphy got the fame. Still, Stapp's experiences led him to coin a truism of his own: ""The universal aptitude for ineptitude makes any human accomplishment an incredible miracle.""
Dinesh Ramde is a graduate student in journalism. E-mail your science questions to dramde@wisc.edu.
