May 23, 2007

some of murphy's law strange designations

before going to designations let's talk a bit about murphy's law & its history ..

from 1947 to 1949 in the usa, the project mx981 took place on muroc, base of the us air force (named later edwards base). the purpose of the project was testing the human tolerance for g-forces during rapid deceleration. tests was using a railroad track propelled by a rocket sled mounted on it, with a series of hydraulic brakes at the end.

after initially using humanoid crash test dummies, medical doctor john paul stapp took their place performing tests. to measure the g-forces, edward murphy proposed using electronic strain gauges attached to the restraining clamps of stapp's harness. murphy's assistant wired the harness, and a trial was run using a chimpanzee.

the sensors provided a zero reading, however; it appeared they had been installed incorrectly, with each sensor wired backwards. It was at this point that a disgusted murphy made his famous pronouncement: « If that guy has any way of making a mistake, he will ».

principle: this law has two aspects:

  • one is obviously a hoax (“malicious nature” would not miss an occasion to bait the poor experimenter), and offers a convenient explanation to the errors of handling (one even came to say “to transform a false result into a right one, it is enough to add to it a constant of the same variable dimension adequately selected and named “murphy's constant””);
  • the other aspect is of statistical type: if many people handle an apparatus and there exists a one & only way to make a mistake, there will be statistically people who will do it. And it is of course of them only that the after-sales service will intend to speak. this second form of the law is confirmed by experiments. one of its corollaries, the law of finagle, sets up a pessimism law.
what interests me as you may have presumed is the 1st aspect, here are some of its strange & paradoxical designations & corollaries:
  • the maximal bother law. it seems it has a military origin. it states: "if there's a fault in a battle plan, there's a big chance the enemy will exploit it. this law is prior to murphy's, & might be from the first world war.
  • the bonaldi effect, relatively known in france in reference to jérôme bonaldi demonstrations failing on the TV shows "nulle part ailleurs" then "on a tout essayé" whereas succeeded during the repetitions.
  • similar to it, the demo effect: an object, software, etc., used daily with no incident, would present a dysfunction during a demonstration, especially in public. exemple : bill gates' presentations of different windows, ending with a famous error on a blue screen.
  • the slice of bread and butter law: a slice of bread and butter almost always falls on the buttered side. in fact the probability depends on the quality of the carpet ...
    talking about this, here's an interesting corollary: the slice / feline paradox: « slice of bread and butter laws affirm definitely butter must touch the floor while feline aerodynamic principles strictly refute the possibility for the cat of landing on the back. If the assemblage of a cat and slice of bread had to land, nature wouldn't be able to resolve this paradox. that why this kind of assemblage never falls »
generaly: murphy's law is reflexive, & acts on itself. nothing guarantee an event will go awry when precisely, according to murphy's law, one expects it. this may drive us to assertions such as: « it will start raining as soon as I start washing my car, except when I wash the car for the purpose of causing rain. » or this one students know well « an exam always starts with fifteen minutes of delay, except the day you come fifteen minutes late. »

to emphasize the paradoxal aspect, we can say it this way: « murphy's law always shows to be true, except when we try to check if it is. »

finally, I will let you meditate on this other paradox by silverman: "if murphy's law can go wrong, it will."