How many times a day do we look at our watch? Do you work all day according to your schedule? This is how days, months, years pass. Centuries have passed. People want to hold time, but can? Shahzad Ahmed tried that. He says in his poem,
“Gujar hi nahi di oh rat main ne
Put your hands over your neck.
Which means Bengali
I did not let that night pass
I left my hand on the watch.
Even if you put your hand on the clock, time cannot be stopped. Well, have we ever wondered why there are 60 minutes in an hour? Or why 60 seconds in a minute? Why is a day 24 hours? Who has determined these fine rules of time?
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Let us find the answer to this question today in Pro-Bangla.
We all know that our blue planet revolves around the sun. Earth orbits the sun once in 365 days. This is called the annual velocity. Earth rotates on its axis once every 24 hours. This is called instantaneous speed. It is for this day and night. I have come to know these in my school life. But how many people have been able to ask the question, why is there a day in 24 hours? Why not in 25 hours?
The ancient Egyptians are credited with dividing a day into 24 hours. They divide the day into ten hours by sundial and add one hour before and one hour after these ten hours. Because there is less light in the morning and evening. These two hours are added to determine that. Thus the day is fixed in 12 hours.
Well what is this shadow? Is it really effective?
To know the identity of the clock we have to go back about three thousand years. When there was no clock. A stone of the same shape as the one in our geometry box was divided into 12 equal parts and each part was held for one hour. We all know that during the day the shadow is never in one direction. Even its length is more or less. And using this simple knowledge, the Egyptians determined the time of day. Anyone can try this test if they want.
What is a shadow clock?
But at night when there is no sun, how does one determine the time?
The intelligence of the ancient Egyptians is astounding. They knew that stars rise and set like the sun. They knew a system of 36 stars. Which was called ‘Decans’. The Egyptians had a design for observing the stars. Which was usually placed on top of the coffin cover. The time was determined at night by calculating the position of the stars with that design. They also divided the night into 12 hours. Thus 12 hours of day and 12 hours of night complete 24 hours.
How did AM-PM come about?
The first clocks that were invented were 24-hour clocks. That is, there used to be a 24 hour mark. Over time, watchmakers realized that if they made a 12-hour watch, it would be much easier and cheaper. From that the journey of AM-PM started.
AM-PM is a Latin word. which is used to denote time. The use of the word in the English language began in the seventeenth century.
AM or “Ante meridiem” refers to the time before noon. That is before twelve noon.
PM or “Post meridiem” refers to the time after noon. That is, after 12 noon.
In short, AM is 12 midnight to 12 noon. PM is 12 noon to 12 midnight.
Which is the most popular watch? 12 hours or 24 hours?
12-hour clocks are not as popular as we think. Even today, 24-hour clock is widely used around the world. We usually cover more about America, England, Australia, Pakistan, India, New Zealand. These countries use a 12-hour clock. That’s why I think the 12 hour clock is everywhere. But the reality is different. Germany, France, Romania, Vietnam use 24-hour clock. Bangladesh Railway schedule is also given on the platform as 24 hours.
Why is an hour 60 minutes? Why not 100 minutes?
In this modern age, we do all calculations in decimal or decimal numbers. Decimal numbers are considered the simplest in this era. We have ten fingers on both hands. So it is easy to calculate on fingers. But in ancient times, numbers were calculated in many other ways. Among which Duodecimal, Sexagesimal is one.
Duodecimal has base 12 and Sexagesimal has base 60
Hours are based on this Sexagesimal. This was done by the Babylonians. Babylon is a city in ancient Mesopotamia. The city of Babylon was located in present-day Iraq. They divide an hour into 60 minutes. This has resulted in some benefits. 60 is a number that is easily divisible by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30. If an hour was divided into 100 parts, it would be somewhat difficult to divide it. Because it could only be divided by 2, 5, 10, 25, 50. This is why the Babylonians divided the minute into 60 seconds. So that time can be divided very easily.
Technology has improved a lot. Now it is possible to keep very precise calculations even within 1000th of a second. We are enjoying GPS through satellite these days. That satellite also determines our location through precise timing.