Cooking, taking the right amount of medicine, putting petrol in the car, knowing the right time to do something. These are just some of the tasks you undertake daily that simply wouldn’t be possible without some aspect of measurement.

Knowing the time would be hard without some sort of timepiece like a clock to measure it. If we didn’t all agree on what the time was and have a way to measure it accurately we would all turn up for things at different times.

You would struggle to bake a cake if you didn’t have scales, have an oven that you can set to the right temperature, and a timer to tell you when the cake is ready to come out. The more you pay attention, the more measurements you will notice you are making. Have a look at this guide created by NPL for some more examples of measurement in daily life.

Really really accurate measurements may not be that important to the measuring you do at home. If you end up with a gram or two more sugar in your cake mix you probably won’t mind that much, but in science, medicine, engineering, electronics and lots of other industries even tiny amounts can have a huge impact, and it’s important that everyone is using the same measurements.

 

 

Here are 5 examples of times things went wrong due to errors in measurement

 

1. Vasa Warship

The Vasa was a very impressive looking warship built in Sweden between 1626 and 1628. It sank within 20 minutes of its maiden voyage, when a gust of wind managed to knock it on its side. There are many theories about what exactly caused the Vasa to sink in the way it did, but we do know that the ship was not symmetrical, and was much heavier on one side.

Archaeologists think they may have found the reason for this crookedness. Four rulers used to build the ship have been recovered, and of these rulers, two used “Swedish Feet” and the other “Amsterdam Feet”. These variations of feet differed by an inch. It doesn’t seem like a lot but when you think of the size of a warship those inches soon add up.

Exterior of Vasa Credit:Alexey M.

 

2. Mars Climate Orbiter

Measurement mistakes didn’t just happen in the olden days. NASA has made a few. The Mars Climate Orbiter was a space probe built in 1998 to orbit Mars and send back information about its climate and atmosphere. It cost $327.6 million to design, build and send into space.

Some of the teams working on the probe were using different units of measurement from each other. One team was working in imperial measurements of inches, feet and pounds, and the other team was using metric units. This confusion and failure to properly adjust for it caused a miscalculation that allowed the probe to get too close to Mars so it entered the atmosphere and got destroyed!

Launch of the Mars Orbiter. Source: Nasa

3. Columbus

Columbus might be known as the man who ‘discovered’ the Americas in 1492, but that wasn’t what he was looking for when he set off on his voyage. He was trying to find a new route to India, China and Japan that didn’t involve sailing around the coast of Africa. The only reason Columbus thought he would be able to achieve this was due to an error in measurement.

There was some disagreement at the time about the size of the globe. Columbus used the calculation posited by a medieval Persian geographer called al-Farghani. al-Farghani gave his measurement of the size of the globe in Arabic miles (roughly 1972 meters). Columbus incorrectly assumed the measurement was in Roman miles which were only 1481 meters long. This meant he thought the earth was a lot smaller than it is. This means he didn’t think it would be too far to sail west all the way around the world to reach Asia. If he had been more accurate in his measurement he might never have tired the voyage at all.

Cristopher Columbus, bust. Engraving by John Sartain from the original portrait presented to William A. Bryan, Esq., of Virginia by H.M. the late Queen Sophia of Holland

4. Hubble Telescope

The Hubble telescope was launched in 1990 and cost NASA billions of pounds to make. After it was in position and the first images were sent back they noticed they were very fuzzy. They discovered that an error of 1.3mm when polishing and testing the mirror had caused part of the edge to be around 0.002mm too flat (That’s about 1/50th of the thickness of a sheet of paper). This tiny error was enough to prevent the space telescope from being able to take focused images.

NASA had to build another mirror that would balance out this error and send it up to the telescope to be installed by astronauts before they could get a clear image.

Photo of galaxy M100 before and after new lens was fitted. Source: NASA

5. French Trains

In 2014 the French Rail Operator decided to undertake a €15million project to improve part of its network. This included ordering some fancy new trains. The rail operator gave the train builders a specification based on standard french platform sizes. Based on these instructions the train manufacturers made the new trains about 20cm wider than before.

Unfortunately, some of the platforms in France were built over 50 years ago, before the standards for platform sizes were introduced and no one thought to check the measurements. This left the rail operator with hundreds of trains that were too big for nearly 1,300 stations. There are also places on the tracks where 2 trains couldnt pass each other. To solve this, they have had to shave several centimetres off station platforms so that the trains can fit. The estimated cost to fix the mistake is €50 million!

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