(A chart showing how quickly your life is slipping through your fingers - each year weighted by its percent of the total lifespan to that point)

This is a graph of an eighty-year life. Each slice represents one year.

The slices’ sizes are weighted by what percentage that year represents of the whole lifespan to that point. At age one, the first year represents 100% of your whole life, so it is given a width of one hundred. Your second year is given a width of fifty, since it represents 50% of your life at age two.

By the time you get to age 21 and look back on the last year, you find that year 20 represents only 4.8% of your life. Furthermore, because each additional year represents a smaller relative portion of your life, three quarters of your life is already over. This is why time seems to go by more quickly as you get older.

In an attempt to offset the depressing nature of this visualization, I have added an unscientific representation of your potential cumulative effect on humanity, good or bad, as your life progresses. This is purely a function of your increasing ability to affect other people in (1) more areas of life and (2) within ever-widening physical bounds as time goes on, combined with the generational effects of your influence on others’ contact with people in their lifetimes.

—JD

“In theory, there is no difference between theory and practice; in practice, there is.” — Chuck Reid

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This is a correlation to the “life is like a roll of toilet paper” idea that my Dad used to quote fairly often (well, about as often as everything else profound he “said”). I say quote – because the way he said it and the twinkle in his grin made me suspicious that he had heard it from someone else at least as clever. […] The diminishing diameter of a roll of toilet paper as it is used means each succeeding revolution yields fewer and fewer square inches of useable surface. So unless you figure out how to use less and less toilet paper as the roll gets smaller, it will go faster.

— Tim Dueck ·

This graph was used in a video titled How Old Can We Get (relevant section starts at 2:53), which was uploaded in October 2011 and as of this note has more than 1.6 million views.

— Joel Dueck (Author) ·

Maximilian Kiener recently created a beautiful interactive visualization of this concept — and gave us a great little window into its history, to boot.

On his site, Kiener states “This theory was first put forward by Paul Janet in 1897” but does not directly offer a source. This piqued my curiosity, so I emailed Kiener to ask about it. He very kindly replied that he had read it in an article by Steve Taylor for New Dawn Magazine: The Speed of Life: Why Time Seems to Speed Up and How to Slow it Down. Taylor writes:

This theory seems to have been first put forward in 1877 by Paul Janet, who suggested the law that, as William James describes it, “the apparent length of an interval at a given epoch of a man’s life is proportional to the total length of the life itself. A child of 10 feels a year as 1/10 of his whole life – a man of 50 as 1/50, the whole life meanwhile apparently preserving a constant length.”

He also quotes Janet as saying:

“Whoever counts many lustra in his memory need only question himself to find that the last of these, the past five years, have sped much more quickly than the preceding periods of equal amount. Let any one remember his last eight or ten school years: it is the space of a century. Compare with them the last eight or ten years of life: it is the space of an hour.”

Taylor is quoting from chapter 15 of William James’s The Principles of Psychology, which in turn gives the source of the Janet quotes as the Revue Philisophique, vol III p. 496.

— Joel (Author) ·