You need the Real Audio player to hear this which you can download for free . If it still doesn't work try this link .

Most people have heard of Murphy's Law. But most people, when they're referring to Murphy's Law, are actually referring to the rather pessimistic Finagle's Law, which is "Anything that can go wrong, will go wrong."

Murphy's Law is quite different, and is actually a message of hope. Not only does it warn you about what things can go wrong, it'll even tell you how you can work around them, so as to make it impossible for Murphy's Law to actually happen.

Now the AeroSpace industry, where things move very rapidly under very harsh and extreme conditions, is an unforgiving environment. And that's where Murphy's Law was first invented.

In 1949, the US Air Force was running a test series (Project MX981) to see what sort of acceleration (or G-forces) a human being could withstand. They were using a volunteer strapped into a rocket sled at what is now called Edward's Air Force Base, in California. The sled would accelerate up to about 1,000 kilometres per hour, and then stop suddenly. One of the volunteer human torpedoes was Colonel Stapp, who was also a medical doctor.

Now our hero, Air Force Captain Edward A. Murphy Jnr., had designed a harness which strapped onto the volunteer. This harness held 16 sensors to measure the acceleration, or the G-forces, on different parts of the poor volunteer. As luck would have it, there were two ways that each sensor could be installed.

The rocket sled took off, and stopped suddenly, generating 40 Gs. Under 1 G, the average person weighs about 70 kg, but under 40 Gs, they weigh 40 times more - about 2.8 tonnes. 40 Gs is an enormous amount of acceleration - enough to push your ears onto the front of your head.

At the end of the experiment Colonel Stapp staggered off the rocket sled with blood-shot eyes and bleeds from a number of bodily orifices. When he looked at the results, he wasn't very happy - all the sensors registered zero! He called for Captain Murphy, who examined the sled - and found that every single one of those 16 sensors had been installed the wrong way round. Colonel Stapp had been strained in vain.

In a voice like thunder, Edward A. Murphy Jnr. proclaimed, "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". This is the true and original form of Murphy's Law.

Of course, you have to notice that little word, "If" in "If there are two or more ways......". Suppose that there's only one way. For example, if you design something that can be installed only one way, then it can't be put in the wrong way.

Consider 240 V electrical power. You definitely don't want the full 240V power to jump directly to any of the other wires. So look at your standard 3-pin 240V electrical power plug. It's not symmetrical. There's only one way to insert it into a 240V electrical power socket.

But sometimes, it doesn't matter which way a thing goes in, so long as it goes in. So another way around Murphy's Law is to design something so that it doesn't matter which way it goes in.

Consider the key.

Your average car key has equal bumps on both sides, so it doesn't matter whether you put it in one way or the other - it always works. But your house key has bumps only on one side - this means that half the time, you'll put it in the wrong way. I guess it's an example of Murphy's Law that after half a century after Murphy's Law was first discovered, the house key manufacturers still haven't heard of it.

So once he had realised the message of Murphy's Law, Murphy himself redesigned the G-force sensors so that they could be installed only one way - and that particular problem was solved.

The next day Murphy's Law was officially declared at a Press Conference about the rocket sled test. A few months later Murphy's Law began to be mentioned in AeroSpace manufacturer's advertisements, and finally by the Flight Safety Foundation. As Murphy's Law spread across the planet, two things happened - people forgot that there was a real person called Murphy, and the Law got modified into the pessimistic form of "If anything can go wrong, it will go wrong".

The fact that many people confuse the optimistic Murphy's Law for the pessimistic Finagle's Law, is proof that Murphy's Law can even act upon itself.