Mercurial > thoughts
view org/man-years.org @ 124:7415863b39f2
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author | rlm |
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date | Tue, 03 Jun 2014 15:33:21 -0400 |
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1 #+title: A Universe of Human Experience2 #+author: Robert McIntyre3 #+email: rlm@mit.edu4 #+description: How many man-years are in a year?5 #+keywords: man-year man-month man-hour universe human experience philosophy6 #+setupfile: ../../aurellem/org/setup.org7 #+include: ../../aurellem/org/level-0.org9 * What is a Man-Hour?10 A [[http://en.wikipedia.org/wiki/Man-hour][/Man-Hour/]] is a term from the field of Management. It is one hour11 of work by one person for a certain task.13 For example, if I have a nine-to-five programming job at [[http://www.imdb.com/title/tt0151804/quotes][Initrode]], but14 I slack off most of the time and only /actually/ work from15 10:00-11:00, then I only put in one man-hour of work a day.17 If my task is simply existing, then I put in 24 man-hours of work18 every day.20 * Experience21 I've often wondered what it would feel like to have more than one22 body, and to experience the same day from different perspectives.24 For example, there are around twenty different majors available at25 MIT. If you had ten different bodies, and each of them double-majored26 in different subjects, then in only four short years you would27 graduate with a degree in every field MIT has to offer. You would have28 experienced forty man-years of college in the process.30 How many man-years does the entire MIT class experience every year?31 [[http://web.mit.edu/fnl/volume/192/century.html][There were around]] $4585$ undergraduates at MIT in the fall of 1982.33 $4585$ students $\times$ $1$ year $=$ $4585$ man-years.35 One person could help lay the first blocks of [[http://en.wikipedia.org/wiki/Great_Pyramid_of_Giza][great Pharaoh Khufu's36 tomb]] and live to see [[http://www.burjkhalifa.ae/][Burj Khalifa]] and they would accrue the same37 amount of experience as the MIT class of '82 did in one year.39 * Forever in a Day40 How many man-years does everyone experience in a day? There are almost41 7 billion people around today, according to [[http://www.census.gov/main/www/popclock.html][www.census.gov]].43 #+begin_src clojure :results output :exports both44 (ns lifespan)45 (use '[clojure [pprint :only [cl-format]]])47 (cl-format *out* "Man-years per day: \n ~R"48 (* 6969492979 ;; people on Earth49 (/ 1 365) ;; years-per-day50 ))51 #+end_src53 #+results:54 : Man-years per day:55 : nineteen million, ninety-four thousand, five hundred one57 Together, we experience almost 20 million years every day!59 A week in the lives of the people of Earth is enough to reach back to60 the age of the dinosaurs.62 * The Infinite Stories of Humanity63 How many man-years is the sum total of human experience? That is, how64 many man-years has every human who has ever lived experienced?66 Using a very rough calculation involving the table from [[http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx][here]] and the67 average human lifespans through the ages found [[http://en.wikipedia.org/wiki/Life_expectancy][here]], I get the68 following:70 #+begin_src clojure :results output :exports both71 (in-ns 'lifespan)73 (def74 time-periods75 "The time periods under question.76 'start' here is taken to be 50,000BC"77 [:start-8000BC78 :8000BC-179 :1-120080 :1200-165081 :1650-175082 :1750-185083 :1850-190084 :1900-195085 :1950-199586 :1995-2011])88 (def births89 "number of people who existed in the given time periods"90 (zipmap91 time-periods92 [ 1137789769 ;; \93 46025332354 ;; |94 26591343000 ;; |95 12782002453 ;; |96 3171931513 ;; | -- from the video at:97 4046240009 ;; | http://www.prb.org/Articles/2002/98 2900237856 ;; | HowManyPeopleHaveEverLivedonEarth.aspx99 3390198215 ;; |100 5427305000 ;; |101 2130327622]));; /104 ;; Confirm that the sum of people agrees with that in the video.105 (assert (= 107602707791 (reduce + (vals births))))107 (def lifespans108 "lifespans in years from birth for the various time periods"109 (zipmap110 time-periods111 [33 ;; start-8000BC \112 22 ;; 8000BC-1 | -- from:113 30 ;; 1-1200 | http://en.wikipedia.org/wiki/114 32 ;; 1200-1650 / Life_expectancy115 35 ;; 1650-1750 \116 35 ;; 1750-1850 |-- from:117 45 ;; 1850-1900 | http://www.deathreference.com/118 66 ;; 1900-1950 | Ke-Ma/Life-Expectancy.html119 66 ;; 1950-1995 /120 70 ;; 1995-2011-------> form:121 ;; http://www.prb.org/DataFinder/Topic/122 ;; Rankings.aspx?ind=6&loc=241123 ]))126 ;;; ----------------------------------------127 ;;; And now for the result!129 ;; This section is just here to make the result look pretty.130 (dorun131 (map println132 (clojure.string/split133 (cl-format134 nil "years of human experience: \n ~R years"135 ;; Multiply each time-period's total number of people136 ;; by those peoples' average lifespan in years to get137 ;; the total number of man-years experienced during138 ;; that period, then add them together.139 (reduce +140 (map *141 (map births time-periods)142 (map lifespans time-periods))))143 #",")))145 #+end_src147 #+results:148 : years of human experience:149 : three trillion150 : three hundred seventy-one billion151 : ninety-three million152 : five hundred ninety-five thousand153 : one hundred eighty-one years155 Humans have already collectively lived about two-hundred times longer156 than the age of the universe.