Measuring One Second: Official Count & Clock Corrections

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    Clock Count Measuring
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Discussion Overview

The discussion revolves around the definition and measurement of one second, including historical definitions and the implications of Earth's rotation on timekeeping. Participants explore the relationship between solar time and clock time, as well as the mechanics of electric clocks.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions how one second is officially measured and the historical context of its definition.
  • Another participant notes that the current definition of a second is based on the oscillations of a cesium-133 atom, while earlier definitions were based on solar days and tropical years.
  • Some participants explain that the discrepancy between a solar day and a sidereal day accounts for the extra 4 minutes needed for the Earth to complete its orbit around the sun.
  • There is a challenge regarding whether clocks would be off by 4 minutes each day due to the difference between solar and sidereal time.
  • One participant asserts that the 24-hour day is constructed arbitrarily to align with solar time rather than sidereal time.
  • Discussion includes technical details about how electric clocks measure time, with references to the frequency of power lines and crystal oscillators.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the Earth's rotation on clock time, with some agreeing on the definitions of time while others contest the practical effects on daily timekeeping. The discussion remains unresolved regarding the impact of the 4-minute discrepancy on clock accuracy.

Contextual Notes

Participants reference various definitions of time and the mechanics of timekeeping devices, but there are unresolved assumptions about the implications of these definitions on daily timekeeping practices.

kyle_soule
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What is the official count of one second? What I mean by this is: how would one go about measuring one second exactly? Basically, at the creation of a second, how was it measured?

Also, if a day is 23 hours and 56 minutes, wouldn't our clocks be off 4 minutes after each day? I understand the system of correction, but until time is 'corrected' for our clocks, we have the incorrect time, correct?
 
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The old definition was 1/86,400 of a mean solar day and then it was 1/31556925.9747 of a tropical year, but since 1967 it has been 9,192,631,770 oscillations of a cesium-133 atom.
 
23 hrs 56 min. is time for one complete rotation of the Earth on its axis. During this time the Earth has moved in its orbit around the sun. The extra 4 minutes is needed to keep the same face toward the sun.
 
Originally posted by mathman
23 hrs 56 min. is time for one complete rotation of the Earth on its axis. During this time the Earth has moved in its orbit around the sun. The extra 4 minutes is needed to keep the same face toward the sun.

That's why it's called a siderial day. Because it is in relation to the backround of stars, not the sun we orbit.
 
People, people, people [mathman and ORW] I knew all this, I was simply asking would our clocks not be off each day increasing by 4 minutes.

jcsd, would you happen to know how many ticks an electric clock goes through before it turns another second?
 
A day is "noon to noon" which means we return to the same position wrt to the sun, not the stars. Hence our day is 24 hours long. The reason our clocks arn't off is because we build them to make 24 hours to be 24 hours. Its all arbitrary really.
 
Originally posted by kyle_soule
People, people, people [mathman and ORW] I knew all this, I was simply asking would our clocks not be off each day increasing by 4 minutes.

jcsd, would you happen to know how many ticks an electric clock goes through before it turns another second?

No I ****ing don't
 
Many electic clocks simply run a motor on 60Hz, thus the speed is tied to the frequency of your power line.

Digital clocks run on a crystal, the frequency of which depends on a selection make by the clocks ciriciut designer. It could vary significaly from clock to clock.
 

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