Murphy’s law is the secret foundations of the universe. You can always trust it to occur, just like death and taxes, and it will often find a way to involve one or both of them in a thoroughly comic fashion.
The general notion is that anything that can go wrong, will go wrong. If you have a dentist appointment that afternoon, you’re going to get a flat tire. If you have a spare tire in your trunk, you’re not going to have a jack. If a friendly driver stops and offers you his, it will turn out that he’s a serial killer. You get the idea.
The law supposedly gets its name from Edward Murphy, an aerospace engineer who was trying to determine how much stress the human body could withstand during rapid deceleration. His experiments took place between 1948 and 1949, and as you might guess, constant screw-ups occurred.
The main incident involved a rocket sled and a chimpanzee. Murphy ordered his assistant to attach strain gauges to the chimp’s harness, so he could measure the g-force that was exerted on them. The sensors did not activate for some reason, and it turned out that they had been wired backwards. Murphy was absolutely furious, and declared “If that guy has any way of making a mistake, he will.” This statement was eventually simplified down to its current form.
Unfortunately, there is no way to protect yourself from Murphy’s Law. No matter how well you prepare, and how many contingency plans you set up, the universe will find a way to screw you. To put it simply, the light at the end of the tunnel is the headlights of an oncoming train.