Notes for the Book: Timelines

I love timelines, especially those scaled depictions of the progress of time from left (the past) to right (the present and the future). Back in the 8th grade, I think it was, I constructed such a timeline on a scroll of paper, on what particular subject I don’t remember, except that it was inspired by articles in National Geographic and included my tracing of an illustration of Quetzalcoatl, something like the one shown at Wikipedia (

In my imaginary book timelines will be a counterpart to the hierarchies of concepts. I started thinking about that yesterday and, this morning, realized that the most prominent timelines that I know of are out there on the web; I don’t need to copy them out of the relevant books.

The big timelines are those that cover all of history, since the beginning of the universe – “big history,” in the current parlance, with human history set in proportional context.

  • One is the Timeline of History presented by Yuval Noah Harari, is his brilliant pop-history book SAPIENS: it begins 13.5 billion years ago and covers, in some two dozen steps, the significant developments of the universe and of humankind. It’s here:
  • Another is the set of thresholds of “big history,” as conceived of by David Christian, in his courses and in his book ORIGIN STORY: A BIG HISTORY OF EVERYTHING (and more loosely in the DK coffee table book BIG HISTORY.) This site,, describes the “Eight Fundamental Thresholds of Big History”; Christian’s book includes a ninth, with a question mark, “a sustainable world order,” that might be achieved in 100 years.
  • And then there’s the classic “Cosmic Calendar” of Carl Sagan, who introduced it in his 1977 book THE DRAGONS OF EDEN and popularized the concept in his 1980 TV series Cosmos; his book of the same name used literal measures of years rather than the relative calendar, presumably because he’d already introduced that in his previous book. The Cosmic Calendar has its own Wikipedia entry:
  • And then, of course, there are any number of traditional timelines covering the geological epochs, or life on Earth, etc., many of them gathered at Wikipedia here:

My plan is to reduce such calendars, or timelines, into small steps, rather like David Christian’s, in order to use them as a context to discuss the big issues of science fiction.

My thought also is to develop timelines of human understanding. This will require some research. I’d like to be able to document, for instance: In 2000 BC, the average informed citizen knew (this much) about the size and age of the world. This changed by (year) when people knew the world was (this big) and much later when scientists discovered that the world was actually (this old). And so on. In part because even the best informed people today don’t appreciate how extensively this knowledge has changed over the past centuries and decades; many take for granted our understanding of the universe that has not emerged until recent decades.

Related to such timelines: appreciations of scale. The classic example is Powers of Ten, the video and book; And more examples since.

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