I keep rediscovering the fact that time is relative. Each clock that I encounter has a different time. Some vary by seconds. Others by minutes or hours. Even the Linux servers I have installed and manage (loblolly.net and lanranger.net) differ from each other by up to an hour or more. Rather use to differ.
Part of the problem is all clocks drift and vary in their ability to keep time. It does not matter whether it's a water clock, a sundial, a Rolex, a Timex, a PC clock or even an atomic clock. They all vary and drift in their ability to keep and measure time.. They do differ in their precision and expense. The newer atomic clocks may drift by less than 1 second every 6 million years. My heirloom windup clock drifts behind by 10 or more minutes each week. Lanranger.net's hardware clock drifts ahead by about 3 to 5 seconds a day. Loblolly.net's hardware clock drifts only a second or so every few days.
By 1850, telegraph operators could send a standardized time to other telegraph operators. (see Engines of Our Ingenuity Episode 272 It took the railroads until 1885 to finally standardize their clocks in each city.. With every town, hamlet and stop with their own time; how would anyone know if the train was early or late. "No the train is not late. Your clock is wrong." Great excuse. Wonder if they were always early and on time by their time? Bet the airlines would like to manage the clocks in each terminal.. Never late and always on time..
Until about 1918, every town and hamlet had their own time. You would have Pittsburgh time, New York time, Peoria time, etc. This is when the telephone was being used by more and more. Sort of begs the question, "Did the Telephone help bring about standardized time?" "You will call at 7PM. Is that NewYork or Philly time?"
With today's commerce taking place on the ribbons of electrons instead of ribbons of steel, having standardized time is even more important.. "When was that sell order for 100,000 shares of Microsoft made?" The correct time can mean millions.
The number one reason for keeping accurate time on your Linux server? It's so easy.. I no longer have an excuse not to. Thanks to the US government. Our tax dollars in use.
Thanks to all the Linux Gurus for providing a wealth of information.. Thanks to Ron Bean for his Clock Mini-HOWTO.. And thanks to the US government for the great time keeping and time keeping research. Much thanks to the Department of Commerce agency, the National Institute of Standards and Technology (NIST), and its military counterpart, the U. S. Naval Observatory (USNO). Without these agencies, keeping accurate time would be very difficult and expensive.. Also thanks to the many and varied agencies and companies for providing time servers. See http://time.gov for more info..
Latest version of this System Clock Mini-HOWTO can be found at http://www.loblolly.net/~rddecker/helppages/MiniHOWTOS/systemclock/systemclock.htm