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Temporal Proposal

Fixing Date

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PERSPECTIVE

We all see dates and times from different angles

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The Global Timeline

1

2

3

4

5

6

7

8

9

Point in absolute time

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Coordinated Universal Time (UTC)

  • A perspective of the global timeline
  • Allows us to keep track of absolute time
  • Primary standard by which the world regulates clocks
  • Defined precisely by scientific community
  • Includes leap seconds
  • Has no relationship to geography
  • Basically the same as GMT, but GMT is not defined precisely by the scientific community

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Local Time

  • A local time is a perspective of time
  • It does not represent a point on the global timeline
  • It is usually not a contiguous timeline (DST)

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UTC Time:�2016-04-09T14:17:47Z

What we know

  • The point in absolute time
  • Whether this time is before or after another point in time

What we don’t know

  • Whether it is morning or night
  • What day of the week it is

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Local Time:�Saturday, April 9, 2016 9:11 AM�

We Know

  • It is Saturday
  • It is morning

We Don’t Know

  • What point this is on the global timeline
  • Whether it is before or after a time from a different locality
  • What the time will be if we add one hour to this time

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TIME ZONES

Uniting Perspectives

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Time Zone Basics

  • A time zone is a region that observes a uniform standard time
  • A time zone is defined by a set of offsets from UTC
  • Offsets are typically in one hour intervals, but not always
    • Nepal Standard Time is UTC +5:45
  • Time zones frequently have multiple offsets
  • There are two main resources for time zones
    • Internet Assigned Numbers Authority (IANA)
    • Windows Time Zones
  • IANA time zones are more widely used, and more accurate

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Time Zone: America/Chicago

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moment('2016-01-01').add(1.5, 'hours').format('LLL')

"January 1, 2016 1:30 AM“

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moment('2016-01-01').add(1.5, 'days').format('LLL')

"January 3, 2016 12:00 AM"

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Timeline Math vs Calendar Math

Timeline math:

  • Refers to operations involving hours, minutes, seconds, milliseconds
  • Works by incrementing or decrementing the position on the global timeline by the number of units in question
  • Can use fractional units

​

Calendar Math:

  • Refers to all operations larger than hours – days, months, years, quarters, etc.
  • Works by moving places on the calendar
  • Cannot be converted to time math
  • Cannot use fractional units

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JodaTime/

NodaTime

Types