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We have an explanation for all 2 xkcd comics, and only 21 (1%) are incomplete. Help us finish them!

## Latest comic

 6/6 Time Title text: You know how Einstein figured out that the speed of light was constant, and everything else had to change for consistency? My theory is like his, except not smart or good.

The original image has a link to a previous comic 1061: EST which is explained here.

## Explanation

 This explanation may be incomplete or incorrect: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.

Cueball suggests a regional time system similar to that used in many societies prior to the invention of mechanical time keeping, such as Japan during the Edo period or the Roman Empire, where the day is separated into two parts based on night and day and then subdivided by hour, minute, and second to give season-variable lengths for each. This method is also named temporal hour, and still in use in the Jewish religion time table.

Exact points in time such as noon, sunrise, or sunset vary on the longitude from east and west, while the length of day and night depends on the latitude. The first problem is solved today by using time zones in which at noon the sun is in most cases at or close to the zenith and sunrise/sunset happens at different times. The second issue is attributed to the tilt of Earth's axis and the curvature of its surface; in summer days are longer than nights and vice versa in winter. In the polar regions there are very long days (and nights) and by Cueball's suggestion the entire months-long polar day would last only 12 of the newly defined "hours".

The caption lays out the punchline in which Randall has very strong feelings and opinions on how standards of time should be measured, but as bad as he believes the official standards are he also recognizes that his own rules would not be popular with other people. After coming to recognize this he has made a hobby or game out of making the worst possible system of measuring time and sharing it with other people.

The caption, though vague, can also be assumed to relate to the gradual deviation of certain regions from the Coordinated Universal Time (UCT) zones with "Daylight Saving Time" that is observed inconsistently and smaller regions opting for awkward fractional increments of deviation from Coordinated Universal Time.

The title text refers to Einstein's special theory of relativity which postulates that the speed of light is the same for all observers, regardless of the motion of the light source (or the observers). An observer at high speed measures the same speed of light as an observer with no motion, measured from the same light source. In classical physics the speed of the moving observer would be added up but in special relativity this isn't true, instead the time runs slower for the moving observer. And additional to this time dilation there is also a length contraction, without which the geometry wouldn't work.

"Today is one of the two days each year when my clocks run at the same speed as everyone else's" refers to the autumnal equinox, when day and night are the same length, therefore causing his clocks to match the world.

## Transcript

[Cueball and White Hat are walking.]
Cueball: Under my time system, the sun rises at 6 am and it sets at 6 pm, as it should.
Cueball: The length of the second is different each day and night, and the current time shifts with your latitude and longitude.
Cueball: Today is one of the two days each year when my clocks run at the same speed as everyone else's.
[Caption below the frame:]
Time standards are so unfixably messy and complicated that at this point my impulse is just to try to make them worse.

## Trivia

• In the title text the name Einstein was originally misspelled as "einstein".
• This comic was released two days after the September equinox 2018 in the US

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