A Universe of Human Experience


Written by:

Robert McIntyre

1 What is a Man-Hour?

A Man-Hour is a term from the field of Management. It is one hour of work by one person for a certain task.

For example, if I have a nine-to-five programming job at Initrode, but I slack off most of the time and only actually work from 10:00-11:00, then I only put in one man-hour of work a day.

If my task is simply existing, then I put in 24 man-hours of work every day.

2 Experience

I've often wondered what it would feel like to have more than one body, and to experience the same day from different perspectives.

For example, there are around twenty different majors available at MIT. If you had ten different bodies, and each of them double-majored in different subjects, then in only four short years you would graduate with a degree in every field MIT has to offer. You would have experienced forty man-years of college in the process.

How many man-years does the entire MIT class experience every year? There were around \(4585\) undergraduates at MIT in the fall of 1982.

\(4585\) students \(\times\) \(1\) year \(=\) \(4585\) man-years.

One person could help lay the first blocks of great Pharaoh Khufu's tomb and live to see Burj Khalifa and they would accrue the same amount of experience as the MIT class of '82 did in one year.

3 Forever in a Day

How many man-years does everyone experience in a day? There are almost 7 billion people around today, according to www.census.gov.

(ns lifespan)
(use '[clojure [pprint :only [cl-format]]])

(cl-format *out* "Man-years per day: \n ~R"
           (* 6969492979 ;; people on Earth
              (/ 1 365)  ;; years-per-day
Man-years per day: 
 nineteen million, ninety-four thousand, five hundred one

Together, we experience almost 20 million years every day!

A week in the lives of the people of Earth is enough to reach back to the age of the dinosaurs.

4 The Infinite Stories of Humanity

How many man-years is the sum total of human experience? That is, how many man-years has every human who has ever lived experienced?

Using a very rough calculation involving the table from here and the average human lifespans through the ages found here, I get the following:

(in-ns 'lifespan)

  "The time periods under question.
    'start' here is taken to be 50,000BC"

(def births
  "number of people who existed in the given time periods"
   [ 1137789769  ;; \
    46025332354  ;;  | 
    26591343000  ;;  |
    12782002453  ;;  |
    3171931513   ;;  | -- from the video at:
    4046240009   ;;  | http://www.prb.org/Articles/2002/
    2900237856   ;;  |    HowManyPeopleHaveEverLivedonEarth.aspx
    3390198215   ;;  |
    5427305000   ;;  |
    2130327622]));; /

;; Confirm that the sum of people agrees with that in the video.
(assert (= 107602707791 (reduce + (vals births))))

(def lifespans
  "lifespans in years from birth for the various time periods"
   [33   ;; start-8000BC  \
    22   ;; 8000BC-1      | -- from: 
    30   ;; 1-1200        | http://en.wikipedia.org/wiki/
    32   ;; 1200-1650     /    Life_expectancy
    35   ;; 1650-1750 \
    35   ;; 1750-1850  |-- from:
    45   ;; 1850-1900  | http://www.deathreference.com/
    66   ;; 1900-1950  |    Ke-Ma/Life-Expectancy.html
    66   ;; 1950-1995 /
    70   ;; 1995-2011-------> form:  
         ;;   http://www.prb.org/DataFinder/Topic/
         ;;      Rankings.aspx?ind=6&loc=241

;;; ----------------------------------------
;;;         And now for the result!

;; This section is just here to make the result look pretty.
 (map println
        nil "years of human experience: \n ~R years"
        ;; Multiply each time-period's total number of people
        ;;  by those peoples' average lifespan in years to get
        ;;  the total number of man-years experienced during
        ;;  that period, then add them together.
        (reduce + 
                (map *
                     (map births time-periods)
                     (map lifespans time-periods))))
years of human experience: 
 three trillion
 three hundred seventy-one billion
 ninety-three million
 five hundred ninety-five thousand
 one hundred eighty-one years

Humans have already collectively lived about two-hundred times longer than the age of the universe.

Author: Robert McIntyre

Created: 2016-07-13 Wed 00:17

Emacs 24.5.1 (Org mode 8.3beta)