Measurement of Time
Time as you all know is very mysterious. Whether time is real or imaginary has been a hot topic of discussion among philosophers for a very long period of TIME!!! How do we measure time? For distance we use a scale and compare the distance with the scale. This cannot be done with time. There is now way we can compare two intervals of time by juxtaposing each other because we cannot go back and forward in time. An event, which repeats itself periodically, was and even today is the basis for time measurement. During early human history, a day was used as the basis of measurement of time. This of course assumes that each day is equal to the next. When need arose for measurement of shorter intervals of time, the sun dial, the hourglass, the pendulum, the balance wheel, oscillations of quartz crystals and the latest the transition between specified energy levels of the caesium atom have been used to measure time. In every case there is the assumption that the interval of time is equal to each other. Of course in every case the assumptions proved to be erroneous. For instance long back people realised that days or not equal to each other.
The most accurate type of timekeeping device is currently the atomic clock, which are accurate to seconds in many thousands of years, and are used to calibrate other clock and timekeeping instruments. Atomic clocks use the spin property of the caesium atom as its basis, and since 1967, the International System of Measurements bases its unit of time, the second, on the properties of caesium. SI defines the second as 9,192,631,770 cycles of the radiation which corresponds to the transition between two electron spin energy levels of the ground state of the 133Cs atom.
Today, the GPS global positioning systems in coordination with the NTP network time protocol can be used to synchronize timekeeping systems across the globe.
Previous to 1967, the second was defined as:
the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.
Not being an astronomer I do not understand what this means. But what baffles me is that the standard cannot be reproduced. We cannot go back to 1900. So how does the standard help? May be the astronomers know better. When the constancy of the standard itself in doubt how do we know whether is the result of non constancy of a) the standard, b) the chronograph whose accuracy we are trying to determine or c) errors of observation in both cases?
Let us see the reasonableness of the assumption of equality of time interval. I believe this is based on the ability of our brain to feel rhythm which again is a repeating event controlled by the brain and say the ability of humans to recognise musical notes, which again being a sound train of fixed frequency is a repeating event?
2 comments:
good evening athimbere ! This is Balaji Bangalore! I read this ! Wonderful! You have taken a very nice concept, but TIME along should clarify!!! Referring to the last paragraph.....reasonableness of the assumption of equality of time interval with relevance to brain, sounds very very logical and acceptable! Nice TIME reading your blog! Thank You! - K.Balaji
Cs also suffers the same fate as use of a 'day' to measure this fascinating entity TIME ????
To elicit comments from the scientific community and interested thinkers, I feel it would help if the Blog design is such that a search for 'concept of Time' should throw up this blog's URL. Can you also direct this to Stephen Hawking by doing a google on him??
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