The Real Story of Murphy's Law

The following is an article from Bathroom Readers' Institute 13th edition Uncle John's All-Purpose Extra Strength Bathroom Reader.

History

The sentiment expressed in Murphy's Law, "Anything that can go wrong, will go wrong," has probably been around as long as there have been things to go wrong. In 1786, for example, Scottish poet Robert Burns wrote, "The best laid schemes o' mice an men gang aft a-gley [are prone to go awry]." But the official Murphy's Law is much more recent. In fact, it's barely 50 years old. [50 when the book was first printed, now it is almost 60 years old - Ed.]

Hot Seat

The rocket sled ride ridden by Lt. Col. John Stapp (Image Source: Edwards Air Force Base History Office)

In 1949, the U.S. Air Force conducted a series of tests on the effect of rapid deceleration on pilots, so they could get a better understanding of how much force people's bodies can tolerate in a plane crash. The tests, part of what was known as Project MX981, consisted of strapping volunteers into a rocket-propelled sled, accelerating the sled, and then slamming on the brakes - bringing the sled to a very abrupt stop. The volunteers wore special harness fitted with 16 sensors that measure the acceleration, or G-forces, on different parts of their body. The harness was the invention of an Air Force captain named Edward A. Murphy ... but the 16 individual sensors were installed by someone else.

Brake Down

On the day of the fateful test, a volunteer named John Paul Stapp was strapped into the sled and the rockets were fired. The test went off as expected - the sled accelerated to a high speed and then abruptly braked to a stop, subjecting his body to such enormous forces that, according to one account, when he stumbled off the sled, his eyes were bloodshot and his nose was bleeding. Stapp's body is believed to have endured forces equivalent to 40G, or 40 times the force of gravity. But no one will ever know for sure, because all 16 of the sensors failed, each one giving a zero reading for the test.

When Murphy examined the harness to see what had gone wrong, he discovered that the technician who had installed the sensors had wired every single one of them backward. Because of a simple human error, Stapp's life had been put at risk in vain. There are varying accounts of what Murphy said next - he may have cursed out the technician responsible for the mistake, saying "If there is any way to do it wrong, he'll find it." Whatever he said originally, at a press conference a few days later Stapp quoted him as having said, "If there are two or more ways to do something and one of those results in a catastrophe, then someone will do it that way." Within months, this expression had became known throughout the aerospace industry as "Murphy's Law."

First Victim

This first version of Murphy's Law might never have become known beyond the participants of Project MX981 had it not been a very sound design and engineering principle. The sensors in Murphy's harness failed not just because they had been installed backward, but also because they were capable of being installed backward. Had they been designed so they could only be installed one way - the correct way - they would never have failed in the first place. A few days later, Murphy himself redesigned the sensors so that they could only be installed one way, and the problem never came up again. (Murphy's Law is why two-pronged electrical plugs are now designed with one prong slightly larger than the other - so they can be plugged in the proper way.) Murphy's Law became a popular principle throughout the aerospace industry, and from there it spread to the rest of the world. But as it spread it also evolved into the popular, more pessimistic form, "If anything can go wrong, it will go wrong."

The Science of Murphy's Law

Murphy's Law of Buttered Bread: "A dropped piece of bread will always land butter side down." Scientific Analysis: The behavior of a piece of bread dropped from table height is fairly predictable. As it falls to the ground it is more likely than not to rotate on its axis; and the distance to the ground is not sufficient for the bread to rotate the full 360 degrees needed for it to land face up. So more often than not, it will land face down.  

Murphy's Law of Lines: "The line next to you will move more quickly than the one you're in." (Also works with a line of traffic.) Scientific Analysis: On average, all the lanes of traffic, or lines at a K-Mart, move at roughly the same rate. That means that if there's a checkout line on either side of you, there's a two in three chance that one of them will move faster than the one you're in.  

Murphy's Law of Socks: "If you lose a sock, it's always from a complete pair." Scientific Analysis: Start with a drawer containing 10 complete pairs of socks, for a total of 20 socks. Now lose one sock, creating one incomplete pair. The drawer now contains 19 socks, 18 of which belong to a complete pair. Now lose a second sock. If all of the remaining socks have the same odds of being lost, there's only 1 chance out of 18 that this lost sock is the mate of the first one that was lost. That means there's a 94.4% chance that it's from one of the complete pairs.  

Murphy's Law of Maps: "The place you're looking for on the map will be gathered at the most inconvenient place on the map, such as an edge, a corner, or near a fold." Scientific Analysis: If you measure out an inch or so from each edge of the map and from each fold, and then calculate the total area of these portions of the map, they'll account for more than half of the total area of the map. So if you pick a point at random, there's a better than 50% chance that it will be in an inconvenient-to-read part of the map.

Zappa's Law and Other Facts of Life