view org/man-years.org @ 158:043412f7a429

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author Robert McIntyre <rlm@mit.edu>
date Thu, 28 Jan 2016 09:36:35 -0800
parents 66396e76dab9
children
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1 #+title: A Universe of Human Experience
2 #+author: Robert McIntyre
3 #+email: rlm@mit.edu
4 #+description: How many man-years are in a year?
5 #+keywords: man-year man-month man-hour universe human experience philosophy
6 #+setupfile: ../../aurellem/org/setup.org
7 #+include: ../../aurellem/org/level-0.org
9 * 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 hour
11 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]], but
14 I slack off most of the time and only /actually/ work from
15 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 work
18 every day.
20 * Experience
21 I've often wondered what it would feel like to have more than one
22 body, and to experience the same day from different perspectives.
24 For example, there are around twenty different majors available at
25 MIT. If you had ten different bodies, and each of them double-majored
26 in different subjects, then in only four short years you would
27 graduate with a degree in every field MIT has to offer. You would have
28 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's
36 tomb]] and live to see [[http://www.burjkhalifa.ae/][Burj Khalifa]] and they would accrue the same
37 amount of experience as the MIT class of '82 did in one year.
39 * Forever in a Day
40 How many man-years does everyone experience in a day? There are almost
41 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 both
44 (ns lifespan)
45 (use '[clojure [pprint :only [cl-format]]])
47 (cl-format *out* "Man-years per day: \n ~R"
48 (* 6969492979 ;; people on Earth
49 (/ 1 365) ;; years-per-day
50 ))
51 #+end_src
53 #+results:
54 : Man-years per day:
55 : nineteen million, ninety-four thousand, five hundred one
57 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 to
60 the age of the dinosaurs.
62 * The Infinite Stories of Humanity
63 How many man-years is the sum total of human experience? That is, how
64 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 the
67 average human lifespans through the ages found [[http://en.wikipedia.org/wiki/Life_expectancy][here]], I get the
68 following:
70 #+begin_src clojure :results output :exports both
71 (in-ns 'lifespan)
73 (def
74 time-periods
75 "The time periods under question.
76 'start' here is taken to be 50,000BC"
77 [:start-8000BC
78 :8000BC-1
79 :1-1200
80 :1200-1650
81 :1650-1750
82 :1750-1850
83 :1850-1900
84 :1900-1950
85 :1950-1995
86 :1995-2011])
88 (def births
89 "number of people who existed in the given time periods"
90 (zipmap
91 time-periods
92 [ 1137789769 ;; \
93 46025332354 ;; |
94 26591343000 ;; |
95 12782002453 ;; |
96 3171931513 ;; | -- from the video at:
97 4046240009 ;; | http://www.prb.org/Articles/2002/
98 2900237856 ;; | HowManyPeopleHaveEverLivedonEarth.aspx
99 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 lifespans
108 "lifespans in years from birth for the various time periods"
109 (zipmap
110 time-periods
111 [33 ;; start-8000BC \
112 22 ;; 8000BC-1 | -- from:
113 30 ;; 1-1200 | http://en.wikipedia.org/wiki/
114 32 ;; 1200-1650 / Life_expectancy
115 35 ;; 1650-1750 \
116 35 ;; 1750-1850 |-- from:
117 45 ;; 1850-1900 | http://www.deathreference.com/
118 66 ;; 1900-1950 | Ke-Ma/Life-Expectancy.html
119 66 ;; 1950-1995 /
120 70 ;; 1995-2011-------> form:
121 ;; http://www.prb.org/DataFinder/Topic/
122 ;; Rankings.aspx?ind=6&loc=241
123 ]))
126 ;;; ----------------------------------------
127 ;;; And now for the result!
129 ;; This section is just here to make the result look pretty.
130 (dorun
131 (map println
132 (clojure.string/split
133 (cl-format
134 nil "years of human experience: \n ~R years"
135 ;; Multiply each time-period's total number of people
136 ;; by those peoples' average lifespan in years to get
137 ;; the total number of man-years experienced during
138 ;; that period, then add them together.
139 (reduce +
140 (map *
141 (map births time-periods)
142 (map lifespans time-periods))))
143 #",")))
145 #+end_src
147 #+results:
148 : years of human experience:
149 : three trillion
150 : three hundred seventy-one billion
151 : ninety-three million
152 : five hundred ninety-five thousand
153 : one hundred eighty-one years
155 Humans have already collectively lived about two-hundred times longer
156 than the age of the universe.