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first draft of man-hours is complete
author Robert McIntyre <rlm@mit.edu>
date Thu, 20 Oct 2011 07:22:13 -0700
parents bfd876105ebd
children 44f31e2126fa
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1:bfd876105ebd 2:c29b950c8729
1 #+title: A Universe of Human Experience 1 #+title: A Universe of Human Experience
2 #+author: Robert McIntyre 2 #+author: Robert McIntyre
3 #+email: rlm@mit.edu 3 #+email: rlm@mit.edu
4 #+description: how many man-years are in a year? 4 #+description: How many man-years are in a year?
5 #+keywords: man-year man-month universe human experience philosophy 5 #+keywords: man-year man-month man-hour universe human experience philosophy
6 #+setupfile: ../../aurellem/org/setup.org 6 #+setupfile: ../../aurellem/org/setup.org
7 #+include: ../../aurellem/org/level-0.org 7 #+include: ../../aurellem/org/level-0.org
8 #+babel: :results output :exports both
8 9
10 * What is a Man-Hour
11
12 A [[http://en.wikipedia.org/wiki/Man-hour][/Man-Hour/]] is a term from the field of Management. It is one hour
13 of work by one person for a certain task.
14
15 For example, if I have a nine-to-five programming job at Initrode, but
16 I slack off most of the time and only /actually/ work from
17 10:00-11:00, then I only put in one man-hour of work a day.
18
19 If my task is simply existing, then I put in 24 man-hours of work
20 every day.
21
22
23 * Experience
24
25 I've often wondered what it would feel like to have more than one
26 body, and to experience the same day from different perspectives.
27
28 For example, there are around twenty different majors available at
29 MIT. If you had ten different bodies, and each of them double-majored
30 in different subjects, then in only four short years you would
31 graduate with a degree in every field MIT has to offer. You would have
32 experienced forty man-years of college in the process.
33
34 How many man-years does the entire MIT class experience every year?
35 [[http://web.mit.edu/fnl/volume/192/century.html][There were around]] $4585$ undergraduates at MIT in the fall of 1982.
36
37 $4585$ students $\times$ $1$ year $=$ $4585$ man-years.
38
39 One person could help lay the first blocks of [[http://en.wikipedia.org/wiki/Great_Pyramid_of_Giza][great Pharaoh Khufu's
40 tomb]] and live to see [[http://www.burjkhalifa.ae/][Burj Khalifa]] and they would accrue the same
41 amount of experience as the MIT class of '82 did in one year.
42
43
44 * Forever in a Day
45
46 How many man-years does everyone experience in a day? There are almost
47 7 billion people around today, according to [[http://www.census.gov/main/www/popclock.html][www.census.gov]].
48
49 #+begin_src clojure
50 (ns lifespan)
51 (use '[clojure.contrib [pprint :only [cl-format]]])
52
53 (cl-format *out* "Man-years per day: \n ~R"
54 (* 6969492979 ;; people on Earth
55 (/ 1 365) ;; years-per-day
56 ))
57 #+end_src
58
59 #+results:
60 : Man-years per day:
61 : nineteen million, ninety-four thousand, five hundred one
62
63 Together, we experience almost 20 million years every day!
64
65 A week in the lives of the people of Earth is enough to reach back to
66 the age of the dinosaurs.
67
68
69 * The Infinite Stories of Humanity
70
71 How many man-years is the sum total of human experience? That is, how
72 many man-years has every human who has ever lived experienced?
73
74 Using a very rough calculation involving the table from [[http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx][here]] and the
75 average human lifespans through the ages found [[http://en.wikipedia.org/wiki/Life_expectancy][here]], I get the
76 following:
77
78 #+begin_src clojure
79 (in-ns 'lifespan)
80 (use '[clojure.contrib [def :only [defvar]]])
81
82 (defvar
83 time-periods
84 [:start-8000BC
85 :8000BC-1
86 :1-1200
87 :1200-1650
88 :1650-1750
89 :1750-1850
90 :1850-1900
91 :1900-1950
92 :1950-1995
93 :1995-2011]
94 "The time periods under question.
95 'start' here is taken to be 50,000BC")
96
97 (defvar births
98 (zipmap
99 time-periods
100 [ 1137789769 ;; \
101 46025332354 ;; |
102 26591343000 ;; |
103 12782002453 ;; |
104 3171931513 ;; | -- from the video at:
105 4046240009 ;; | http://www.prb.org/Articles/2002/
106 2900237856 ;; | HowManyPeopleHaveEverLivedonEarth.aspx
107 3390198215 ;; |
108 5427305000 ;; |
109 2130327622]);; /
110 "number of people who existed in the given time periods")
111
112 ;; Confirm that the sum of people agrees with that in the video.
113 (assert (= 107602707791 (reduce + (vals births))))
114
115 (defvar lifespans
116 (zipmap
117 time-periods
118 [33 ;; start-8000BC \
119 22 ;; 8000BC-1 | -- from:
120 30 ;; 1-1200 | http://en.wikipedia.org/wiki/
121 32 ;; 1200-1650 / Life_expectancy
122 35 ;; 1650-1750 \
123 35 ;; 1750-1850 |-- from:
124 45 ;; 1850-1900 | http://www.deathreference.com/
125 66 ;; 1900-1950 | Ke-Ma/Life-Expectancy.html
126 66 ;; 1950-1995 /
127 70 ;; 1995-2011-------> form:
128 ;; http://www.prb.org/DataFinder/Topic/
129 ;; Rankings.aspx?ind=6&loc=241
130 ])
131 "lifespans in years from birth for the various time periods")
132
133
134
135 ;; multiply each time-period's total number of people
136 ;; by those people's average lifespan in years to get
137 ;; the total number of man-years experienced during
138 ;; that period, then add them together.
139
140 (dorun
141 (map println
142 (clojure.contrib.string/split
143 #","
144 (cl-format nil "years of human experience: \n ~R years"
145 (reduce +
146 (map *
147 (map births time-periods)
148 (map lifespans time-periods)))))))
149
150 #+end_src
151
152 #+results:
153 : years of human experience:
154 : three trillion
155 : three hundred seventy-one billion
156 : ninety-three million
157 : five hundred ninety-five thousand
158 : one hundred eighty-one years
159
160
161
162 Humans have already collectively lived far longer than the age of the
163 universe.