How Was Time of 1 second Was Decided First Time ?

Replies

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  Anoop Mathew

  My best guess (this is purely without refering any legitimate sources) is that people who observed the sky understood that it took the Moon 24 hours to revolve around the Earth - this happened very slowly indeed and was perfected over the eras.
  
  Man must have observed the shadow that keeps changing direction around an object (say - a small plant) and deciphered that it was the Sun and Moon that was behind changing of the direction of shadows. When this kept occuring repeatedly, man understood the importance of working in the day and sleeping when it's dark. This naturally created a routine in man's life. As the routine continued on to evolution, man developed himself through other innovations and became the farmer. Once a need arised in this farmer's life when he wanted to meet another farmer at a particular time during the day. So this farmer told his fellow farmer that they would meet when the shadow reaches a particular stone (which they used as marking). This concept might have gone widespread and with perfected everyone started using a sun dial.
  
  There are no exact evidences as to who discovered this concept. So refer to #-Link-Snipped-# for doubts on origin of Sundial.
  
  You'll also have to first doubt about how 360 degrees equals one circle came into existence in the first place.
  
  However there are a variety of concepts discussed here #-Link-Snipped-# relating to making of the minute hand and also of the second hand after perfecting the mechanical hour hand clock concept. This link also shows various types of time marking systems such as the French Decimal time. The survival of the fittest concept is established today in our living rooms and gadgets as clocks.
  
  P.S: Well if you don't believe my story, make your own. But what would you choose to believe? (Life of Pi) ;-)
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  Abhishek Rawal

  anoopthefriend

  My best guess (this is purely without refering any legitimate sources) is that people who observed the sky understood that it took the Moon 24 hours to revolve around the Earth - this happened very slowly indeed and was perfected over the eras.

  But if a second was not known, from where 24 hours came into existence ? 😨
• 

  Anoop Mathew

  Abhishek Rawal

  But if a second was not known, from where 24 hours came into existence ? 😨

  That's what I mentioned -

  this happened very
  slowly indeed and was perfected over the eras.

  And I believe that the larger entity was discovered prior to the smaller entity. Necessity is the mother of invention. When you read the link to show the history of clock face, you'd see how they've used the mechanical motion to derive a minute hand from an hour hand, and later on a second-minute hand (now known as second hand) from the mechanical motion of the minute hand.
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  Jeffrey Arulraj

  Well Cesium is the most stable element in earth Standard temperature Pressure condition
  
  That is why we use Cesium as reference
  
  Man assumed second by comparing the actual solar time with the vibrations of Cesium crystals
  
  We had better understanding of solar time since ages
• 

  Nayan Goenka

  Conqueror

  Well Cesium is the most stable element in earth Standard temperature Pressure condition
  
  That is why we use Cesium as reference
  
  Man assumed second by comparing the actual solar time with the vibrations of Cesium crystals
  
  We had better understanding of solar time since ages

  
  I am not sure about this element. But i heard that they studied vibrations of krypton crystals when exposed to some kind of solar energy set up. this gave them one cycle and the time taken by that one cycle came to be known as 1 second.
• 

  Jeffrey Arulraj

  Nayan Goenka

  I am not sure about this element. But i heard that they studied vibrations of krypton crystals when exposed to some kind of solar energy set up. this gave them one cycle and the time taken by that one cycle came to be known as 1 second.

  Can you pls post the source of this post?
  
  I am not sure any atom has a complete cycle lasting for a whole second
• 

  Nayan Goenka

  Sorry for that mix up. I got confused between 2 different topics.
  
  Here is the perfect definition of 1 second. And yes it focuses on Cesium
  
  
  
  

  The second (abbreviation, s or sec) is the Standard International ( #-Link-Snipped-# ) unit of time. One second is the time that elapses during 9,192,631,770 (9.192631770 x 10 9 ) cycles of the radiation produced by the transition between two levels of the cesium 133 atom.
  There are other expressions for the second. It is the time required for an #-Link-Snipped-# to propagate 299,792,458 meters (2.99792458 x 10 8 m) through a vacuum. This figure is sometimes rounded to 3.00 x 10 8m, or 300,000 kilometers (3.00 x 10 5 km). One second is equal to 1/86,400 of a mean solar day. This is easy to derive from the fact that there are 60 seconds in a minute, 60 minutes in an hour, and 24 hours in a mean solar day. This definition is, however, subject to limited accuracy because of irregularities in the earth's orbit around the sun.
  Engineers and scientists often use smaller units than the second by attaching power-of-10 #-Link-Snipped-# s. One millisecond is 10 -3 s; one microsecond is 10 -6 s; one nanosecond is 10 -9 s; one picosecond is 10 -12 s. During these spans of time, respectively, an EM field propagates through a vacuum over distances of approximately 300 kilometers, 300 meters, 300 millimeters, and 300 micrometers.
  The second is sometimes specified as a unit of angular measure, especially in astronomy and global positioning. In these contexts, it is also known as an arc second or a second of arc, and is equal to exactly 1/3600 of an angular degree or 1/1,296,000 of a circle. Sixty arc seconds comprise an arc minute; 60 arc minutes comprise an angular degree. One arc second of latitude at the earth's surface corresponds to a north-south distance of only about 31 m.

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