Overview Dates Time And Calendars

The Problem#

Our objective is to find a methodology where we can always determine the precise time occurrence or an event.

DST's twice-annual shifts in recorded time cause complications, as shown in the following example. During a North American time change, an autumn night during which clocks are reset from 2 a.m. DST to 1 a.m. Standard Time, times between 1 a.m. and 2 a.m. will occur twice, causing confusion in transport schedules, payment systems, etc.

DST's annual autumn shift in recorded time—which causes an hour of the same numerical name to be recorded twice—also means that people born during one of those two hours have no way to know which of standard time or DST was used to record the time of their birth, unless someone such as a parent makes a note of it; birth certificates rarely keep track of this.

A British politician, Lord Balfour, noted the legal complications in British law: "Supposing some unfortunate Lady was confined with twins and the first child was born 10 minutes before 3 o'clock British Summer Time. ... The time of birth of the two children would be reversed. ... Such an alteration might conceivably affect the property and titles in that House."

Time And Epochs#

Some information about Time And Epochs and how they are utilized within computing systems.

Why is Time Important#

Some reasons Why is Time Important.

Time and Computing [1]#

We will not go into the philosophical discussions of time but rather limit our discussions to the realist view, to which Sir Isaac Newton subscribed, in which time itself is something that can be measured. Further for these discussions we will ignore the relativistic effects of time and assume we are all within the same relativistic context.

"Time is currently one of the few fundamental quantities. These are quantities which cannot be defined via other quantities because there is nothing more fundamental than what is presently known. Thus, similar to definition of other fundamental quantities (like space and mass), time is defined via measurement.

The origins of our current measurement system go back to the Sumerian civilization of approximately 2000 BCE. This is known as the Sumerian Sexagesimal System based on the number 60. 60 seconds in a minute, 60 minutes in an hour - and possibly a calendar with 360 (60x6) days in a year (with a few more days added on). Twelve also features prominently, with roughly 12 hours of day and 12 of night, and roughly 12 months in a year (especially in a 360 day year).

So time measurement, at the lowest basis is a number of discrete increments of from one point to another within a time line.

What Time is it?#

If someone would reply, "It is 12 O'clock" can we determine what time it is?

We would only know what time it is if we are within the same context that the replying party's context. This context is based on the context elements of "Time Zone" and "Calendar". That is to say, we would know what time it is if we are referencing the same time zone and calendar.


There are various calendars currently in use throughout the world today.

So even if we would would agree what time zone we are in, if we did not know what calendar we were using, we could be on a different calendar and therefore be day or even a year.

Time Zones and Daylight Savings Time#

Time Zones and the associated daylight savings time offsets are the big issue with time because:
  • There is no World Wide Standard that controls Time Zone or daylight savings time.
  • DST is not universally accepted and many localities do not observe it.
  • DST is changed for various reasons within a "local" and therefore it is necessary to record in addition to the Calendar and Time Zone, the DST offset that was in effect.

The solution?#

We can eliminate a lot of the confusion of computing time if all times are set to UTC time as then there is no Time Zone or DST component. THen all that is necessary is to note the calendar that was in effect at the time.

Hope for Time Zone Issues?#

The tz database is a possible source for accurate Time Zone and Daylight Savings Time Information. As an online source of Time Zone information that is updated several times a year.

In addition to the c code on that site there Java API

If you were Born Today#

Of an interesting note on Calendars. If you were born today at this time and you were using the Islamic Calendar, you can not determine when your 25th birthday will occur.

More Information#

There might be more information for this subject on one of the following:
[#1] http://en.wikipedia.org/wiki/Time#Measurement