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update to clojure 1.4
author Robert McIntyre <rlm@mit.edu>
date Mon, 30 Apr 2012 03:23:12 -0500
parents 44f31e2126fa
children 66396e76dab9
rev   line source
rlm@1 1 #+title: A Universe of Human Experience
rlm@1 2 #+author: Robert McIntyre
rlm@1 3 #+email: rlm@mit.edu
rlm@2 4 #+description: How many man-years are in a year?
rlm@2 5 #+keywords: man-year man-month man-hour universe human experience philosophy
rlm@1 6 #+setupfile: ../../aurellem/org/setup.org
rlm@1 7 #+include: ../../aurellem/org/level-0.org
rlm@1 8
rlm@3 9 * What is a Man-Hour?
rlm@2 10 A [[http://en.wikipedia.org/wiki/Man-hour][/Man-Hour/]] is a term from the field of Management. It is one hour
rlm@2 11 of work by one person for a certain task.
rlm@2 12
rlm@4 13 For example, if I have a nine-to-five programming job at [[http://www.imdb.com/title/tt0151804/quotes][Initrode]], but
rlm@2 14 I slack off most of the time and only /actually/ work from
rlm@2 15 10:00-11:00, then I only put in one man-hour of work a day.
rlm@2 16
rlm@2 17 If my task is simply existing, then I put in 24 man-hours of work
rlm@2 18 every day.
rlm@2 19
rlm@2 20 * Experience
rlm@2 21 I've often wondered what it would feel like to have more than one
rlm@2 22 body, and to experience the same day from different perspectives.
rlm@2 23
rlm@2 24 For example, there are around twenty different majors available at
rlm@2 25 MIT. If you had ten different bodies, and each of them double-majored
rlm@2 26 in different subjects, then in only four short years you would
rlm@2 27 graduate with a degree in every field MIT has to offer. You would have
rlm@2 28 experienced forty man-years of college in the process.
rlm@2 29
rlm@2 30 How many man-years does the entire MIT class experience every year?
rlm@2 31 [[http://web.mit.edu/fnl/volume/192/century.html][There were around]] $4585$ undergraduates at MIT in the fall of 1982.
rlm@2 32
rlm@2 33 $4585$ students $\times$ $1$ year $=$ $4585$ man-years.
rlm@2 34
rlm@2 35 One person could help lay the first blocks of [[http://en.wikipedia.org/wiki/Great_Pyramid_of_Giza][great Pharaoh Khufu's
rlm@2 36 tomb]] and live to see [[http://www.burjkhalifa.ae/][Burj Khalifa]] and they would accrue the same
rlm@2 37 amount of experience as the MIT class of '82 did in one year.
rlm@2 38
rlm@2 39 * Forever in a Day
rlm@2 40 How many man-years does everyone experience in a day? There are almost
rlm@2 41 7 billion people around today, according to [[http://www.census.gov/main/www/popclock.html][www.census.gov]].
rlm@2 42
rlm@4 43 #+begin_src clojure :results output :exports both
rlm@2 44 (ns lifespan)
rlm@4 45 (use '[clojure [pprint :only [cl-format]]])
rlm@2 46
rlm@2 47 (cl-format *out* "Man-years per day: \n ~R"
rlm@2 48 (* 6969492979 ;; people on Earth
rlm@2 49 (/ 1 365) ;; years-per-day
rlm@2 50 ))
rlm@2 51 #+end_src
rlm@2 52
rlm@2 53 #+results:
rlm@2 54 : Man-years per day:
rlm@2 55 : nineteen million, ninety-four thousand, five hundred one
rlm@2 56
rlm@2 57 Together, we experience almost 20 million years every day!
rlm@2 58
rlm@2 59 A week in the lives of the people of Earth is enough to reach back to
rlm@2 60 the age of the dinosaurs.
rlm@2 61
rlm@2 62 * The Infinite Stories of Humanity
rlm@2 63 How many man-years is the sum total of human experience? That is, how
rlm@2 64 many man-years has every human who has ever lived experienced?
rlm@2 65
rlm@2 66 Using a very rough calculation involving the table from [[http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx][here]] and the
rlm@2 67 average human lifespans through the ages found [[http://en.wikipedia.org/wiki/Life_expectancy][here]], I get the
rlm@2 68 following:
rlm@2 69
rlm@4 70 #+begin_src clojure :results output :exports both
rlm@2 71 (in-ns 'lifespan)
rlm@2 72
rlm@4 73 (def
rlm@2 74 time-periods
rlm@4 75 "The time periods under question.
rlm@4 76 'start' here is taken to be 50,000BC"
rlm@2 77 [:start-8000BC
rlm@2 78 :8000BC-1
rlm@2 79 :1-1200
rlm@2 80 :1200-1650
rlm@2 81 :1650-1750
rlm@2 82 :1750-1850
rlm@2 83 :1850-1900
rlm@2 84 :1900-1950
rlm@2 85 :1950-1995
rlm@4 86 :1995-2011])
rlm@2 87
rlm@4 88 (def births
rlm@4 89 "number of people who existed in the given time periods"
rlm@2 90 (zipmap
rlm@2 91 time-periods
rlm@2 92 [ 1137789769 ;; \
rlm@2 93 46025332354 ;; |
rlm@2 94 26591343000 ;; |
rlm@2 95 12782002453 ;; |
rlm@4 96 3171931513 ;; | -- from the video at:
rlm@4 97 4046240009 ;; | http://www.prb.org/Articles/2002/
rlm@4 98 2900237856 ;; | HowManyPeopleHaveEverLivedonEarth.aspx
rlm@4 99 3390198215 ;; |
rlm@4 100 5427305000 ;; |
rlm@4 101 2130327622]));; /
rlm@4 102
rlm@2 103
rlm@2 104 ;; Confirm that the sum of people agrees with that in the video.
rlm@2 105 (assert (= 107602707791 (reduce + (vals births))))
rlm@2 106
rlm@4 107 (def lifespans
rlm@4 108 "lifespans in years from birth for the various time periods"
rlm@2 109 (zipmap
rlm@2 110 time-periods
rlm@2 111 [33 ;; start-8000BC \
rlm@2 112 22 ;; 8000BC-1 | -- from:
rlm@2 113 30 ;; 1-1200 | http://en.wikipedia.org/wiki/
rlm@2 114 32 ;; 1200-1650 / Life_expectancy
rlm@2 115 35 ;; 1650-1750 \
rlm@2 116 35 ;; 1750-1850 |-- from:
rlm@2 117 45 ;; 1850-1900 | http://www.deathreference.com/
rlm@2 118 66 ;; 1900-1950 | Ke-Ma/Life-Expectancy.html
rlm@2 119 66 ;; 1950-1995 /
rlm@2 120 70 ;; 1995-2011-------> form:
rlm@2 121 ;; http://www.prb.org/DataFinder/Topic/
rlm@2 122 ;; Rankings.aspx?ind=6&loc=241
rlm@4 123 ]))
rlm@2 124
rlm@2 125
rlm@4 126 ;;; ----------------------------------------
rlm@4 127 ;;; And now for the result!
rlm@3 128
rlm@3 129 ;; This section is just here to make the result look pretty.
rlm@2 130 (dorun
rlm@2 131 (map println
rlm@4 132 (clojure.string/split
rlm@3 133 (cl-format
rlm@3 134 nil "years of human experience: \n ~R years"
rlm@4 135 ;; Multiply each time-period's total number of people
rlm@4 136 ;; by those peoples' average lifespan in years to get
rlm@4 137 ;; the total number of man-years experienced during
rlm@4 138 ;; that period, then add them together.
rlm@3 139 (reduce +
rlm@3 140 (map *
rlm@3 141 (map births time-periods)
rlm@4 142 (map lifespans time-periods))))
rlm@4 143 #",")))
rlm@2 144
rlm@2 145 #+end_src
rlm@2 146
rlm@2 147 #+results:
rlm@2 148 : years of human experience:
rlm@2 149 : three trillion
rlm@2 150 : three hundred seventy-one billion
rlm@2 151 : ninety-three million
rlm@2 152 : five hundred ninety-five thousand
rlm@2 153 : one hundred eighty-one years
rlm@2 154
rlm@4 155 Humans have already collectively lived about two-hundred times longer
rlm@4 156 than the age of the universe.