Konstantinos Charatzas

Time Unit Graph

An interactive explorer of how various units of time from different cultures are related to each other.

SPEC
Type
Interactive graph, drawn in SVG
Stack
TypeScript, d3-force, d3-zoom
A picture of the time unit graph. Blue circles for units and ringed orange circles for observed sources such as the new moon and the March equinox, with arrows linking each time unit to what it is derived from.

Open the graph in a new window

The idea

While there are many units of time in use across cultures and history, the natural sources for them are relatively few. I wanted to explore the following concepts:

  • What are the various “root” sources of time units?
  • What scales do time units tend to cluster around throughout cultures and history? i.e. what scales of time do people tend to find meaningful to refer to often?
  • What units of time break from the above and why? For example, a week is 7 days despite there being no observed phenomena at 7 day scales.

Reading it

Filled circles are units. Ringed circles are sources: things you watch happen, like the day/night cycle, a new moon or a caesium atom’s transition. In “Length mode”, Depth is length, shorter above longer on a log scale, so units of a similar length line up whether or not they are intentionally linked. NOTE: Where a long stretch of lengths is empty it is drawn shorter, and the scale on the left edge marks the break.

Lines/arrows are relations:

  • A solid arrow is a definition: e.g. a week is defined by being 7 days.
  • A dash-dot line is a relation rather than a definition, so a synodic month is roughly 29.53 days, because it is defined not by days but by the lunar cycle.