**Ten Out Of Ten**

#### Tom Dormer discusses the origin our timekeeping system and attempts made at changing it

One second is officially defined as the amount of time taken for a Caesium-133 atom to oscillate 9,192,631,770 times. This is designed to have a value equal to 1/86400 of an average day (86400 = 24hrs x 60mins x 60 seconds). Of course, splitting a day how we do is completely arbitrary in terms of science and maths. So why have most physical measurements been decimalised, but the measure of time has not?

Splitting a day into 24 hours goes back to the Babylonians. They used a sexagesimal system (counting in 60s) for both mathematics and astronomy, so when it came to splitting a day, 60 and 24 were the obvious choices. They used this system because 60 is easier to divide into fractions, as opposed to base 10 which only has three divisors.

“Splitting a day into 24 hours goes back to the Babylonians”

However, using this system has some obvious disadvantages. For example, if you want to count how many seconds have passed, you must first multiply the minutes by 60 and the hours by 24 x 60 to convert the time into seconds. Only then can you subtract one value from the other.

If we were to use a decimal system, this question simplifies dramatically. It becomes a case of removing the colons and subtracting. For example, 60:40:75 to 67:50:90 = 675090 – 604075 = 71015 seconds. Easy.

This ease of a decimal system did not go unnoticed. In 1793 the French introduced ‘French Revolutionary Time’ placing noon at 5:00:00 with 100,000 seconds in a day. They started manufacturing clocks with both decimal time and standard time for conversion.

However, the move proved unpopular with the people due to the cost incurred to changing all the clocks. ‘Standard Time’ was still primarily used, resulting in the mandatory use of French Revolutionary Time being stopped just 2 years later (ironically in the same law that introduced the metric system for length and mass).

“However, the move proved unpopular… due to the cost incurred to changing all the clocks”

While other attempts to decimalise time have been made since then, all projects have been eventually dropped for the current system. So, while the use of ‘standard time’ has its firm position in society, it is very unlikely we will ever see the decimalisation of time again.