A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC), to accommodate the difference between precise time (as measured by atomic clocks) and imprecise observed solar time (known as UT1 and which varies due to irregularities and long-term slowdown in the Earth's rotation).
The relevant international standards body has been debating whether or not to continue the practice. In any case, for the scientific minded here is a study titled How Long Is A minute. LINK
The most widely used numeral system is decimal (base 10), a system that probably originated because it made it easy for humans to count using their fingers.
However, whatever civilization that first divided the day into smaller parts, probably the Egyptians, used the duodecimal (base 12) and sexagesimal (base 60) system.
The Egyptians used sundials which were simply stakes placed in the ground that indicated time by the length and direction of the shadow.
As early as 1500 B.C., they had developed a more advanced sundial. It was a T-shaped bar placed in the ground that divided the interval between sunrise and sunset into 12 parts. In those days the length of an hour varied during the year, with the summer hours being much longer than the winter hours.
This division reflected Egypt's use of the duodecimal system. The number 12 is attributed either to the fact that it equals the number of lunar cycles in a year or the number of finger joints on each hand (three in each of the four fingers, excluding the thumb). This makes it possible to count to twelve on one hand!
Egyptian astronomers observed a set of 36 stars that divided the circle of the heavens into equal parts, thus making the passage of night possible. The clepsydra, or water clock, was also used to record time during the night. A specimen was found that dated back to 1400 B.C. and it was inscribed to divide night into 12 parts.
Once both the light and dark hours were divided into 12 parts the concept of a 24-hour day was was established, but the concept of fixed-length hours did not come about until Greek astronomers began using such a system for their calculations. Common people did not begin using fixed length hours until mechanical clocks appeared in Europe during the 14th century.
Advances in the science of timekeeping have changed how hours, minutes and seconds are defined.The details are not important to us non-scientists. Suffice it to say that in 1967 the second was redefined as the duration of 9,192,631,770 energy transitions of the cesium atom. This ushered in atomic timekeeping and Coordinated Universal Time (UTC). Zulu time
This zulu time reminds me of the time in the military when everybody used the term "klick" to describe distance. Here's a little secret...nobody knew how long a klick was! At least not in those days. I heard it used for everything from a hundred yards to a mile!
Nobody knows where the term came from, but it's generally believed to be derived from kilometer which the US and UK military began using since WWI when they combined operations with the French. Maybe the English know how long a kilometer is, but most Americans (even in the military) have no idea.
Actually, one klick would equal a kilometer which is 1,000 meters, or 3,284.84 feet which in US terms in about 6/10ths of a mile.
Most military personnel are also probably not aware that klick with a "k" is different than click with a "c." Click spelled with a "c" refers to one inch of distance at 100 yards and it's the sound you hear when you adjust the sights on your rifle.
When I was in the military the term "zulu" was occasionally used, but I never knew what it meant until now. It's just a military and aviation term for what used to be called Greenwich Mean Time which is now UTC.
Now back to the subject of how long is a minute. How long do we perceive a minute to be? There is an interactive site where you can see how close you can estimate a minute. Counting in my head I estimated one minute to be 59 seconds. When trying the same experiment with out counting, my estimate was way off...only 36 seconds. Allowing myself a do-over did not yield results that were any better..89 seconds. You can give it a shot HERE.
40 Things You Can Do in One Minute or Less That Will Make Your Life That Much Better
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