1.1 --- a/org/man-years.org	Thu Oct 20 01:13:26 2011 -0700
     1.2 +++ b/org/man-years.org	Thu Oct 20 07:22:13 2011 -0700
     1.3 @@ -1,8 +1,163 @@
     1.4  #+title: A Universe of Human Experience
     1.5  #+author: Robert McIntyre
     1.6  #+email: rlm@mit.edu
     1.7 -#+description: how many man-years are in a year?
     1.8 -#+keywords: man-year man-month universe human experience philosophy
     1.9 +#+description: How many man-years are in a year?
    1.10 +#+keywords: man-year man-month man-hour universe human experience philosophy
    1.11  #+setupfile: ../../aurellem/org/setup.org
    1.12  #+include: ../../aurellem/org/level-0.org
    1.13 +#+babel: :results output :exports both
    1.14  
    1.15 +* What is a Man-Hour
    1.16 +
    1.17 +A [[http://en.wikipedia.org/wiki/Man-hour][/Man-Hour/]] is a term from the field of Management.  It is one hour
    1.18 +of work by one person for a certain task. 
    1.19 +
    1.20 +For example, if I have a nine-to-five programming job at Initrode, but
    1.21 +I slack off most of the time and only /actually/ work from
    1.22 +10:00-11:00, then I only put in one man-hour of work a day.
    1.23 +
    1.24 +If my task is simply existing, then I put in 24 man-hours of work
    1.25 +every day.
    1.26 +
    1.27 +
    1.28 +* Experience
    1.29 +
    1.30 +I've often wondered what it would feel like to have more than one
    1.31 +body, and to experience the same day from different perspectives. 
    1.32 +
    1.33 +For example, there are around twenty different majors available at
    1.34 +MIT. If you had ten different bodies, and each of them double-majored
    1.35 +in different subjects, then in only four short years you would
    1.36 +graduate with a degree in every field MIT has to offer. You would have
    1.37 +experienced forty man-years of college in the process.
    1.38 +
    1.39 +How many man-years does the entire MIT class experience every year?
    1.40 +[[http://web.mit.edu/fnl/volume/192/century.html][There were around]] $4585$ undergraduates at MIT in the fall of 1982.
    1.41 +
    1.42 +$4585$ students $\times$ $1$ year $=$ $4585$ man-years.
    1.43 +
    1.44 +One person could help lay the first blocks of [[http://en.wikipedia.org/wiki/Great_Pyramid_of_Giza][great Pharaoh Khufu's
    1.45 +tomb]] and live to see [[http://www.burjkhalifa.ae/][Burj Khalifa]] and they would accrue the same
    1.46 +amount of experience as the MIT class of '82 did in one year.
    1.47 +
    1.48 +
    1.49 +* Forever in a Day
    1.50 +
    1.51 +How many man-years does everyone experience in a day? There are almost
    1.52 +7 billion people around today, according to [[http://www.census.gov/main/www/popclock.html][www.census.gov]]. 
    1.53 +
    1.54 +#+begin_src clojure
    1.55 +(ns lifespan)
    1.56 +(use '[clojure.contrib [pprint :only [cl-format]]])
    1.57 +
    1.58 +(cl-format *out* "Man-years per day: \n ~R"
    1.59 +           (* 6969492979 ;; people on Earth
    1.60 +              (/ 1 365)  ;; years-per-day
    1.61 +              ))
    1.62 +#+end_src
    1.63 +
    1.64 +#+results:
    1.65 +: Man-years per day: 
    1.66 +:  nineteen million, ninety-four thousand, five hundred one
    1.67 +
    1.68 +Together, we experience almost 20 million years every day!
    1.69 +
    1.70 +A week in the lives of the people of Earth is enough to reach back to
    1.71 +the age of the dinosaurs.
    1.72 +
    1.73 +
    1.74 +* The Infinite Stories of Humanity
    1.75 +  
    1.76 +How many man-years is the sum total of human experience? That is, how
    1.77 +many man-years has every human who has ever lived experienced?  
    1.78 +
    1.79 +Using a very rough calculation involving the table from [[http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx][here]] and the
    1.80 +average human lifespans through the ages found [[http://en.wikipedia.org/wiki/Life_expectancy][here]], I get the
    1.81 +following:
    1.82 +
    1.83 +#+begin_src clojure 
    1.84 +(in-ns 'lifespan)
    1.85 +(use '[clojure.contrib [def :only [defvar]]])
    1.86 +
    1.87 +(defvar
    1.88 +  time-periods
    1.89 +  [:start-8000BC
    1.90 +   :8000BC-1    
    1.91 +   :1-1200      
    1.92 +   :1200-1650   
    1.93 +   :1650-1750   
    1.94 +   :1750-1850   
    1.95 +   :1850-1900   
    1.96 +   :1900-1950   
    1.97 +   :1950-1995   
    1.98 +   :1995-2011]
    1.99 +  "The time periods under question.
   1.100 +    'start' here is taken to be 50,000BC")
   1.101 +
   1.102 +(defvar births
   1.103 +  (zipmap
   1.104 +   time-periods
   1.105 +   [ 1137789769  ;; \
   1.106 +    46025332354  ;;  | 
   1.107 +    26591343000  ;;  |
   1.108 +    12782002453  ;;  |
   1.109 +     3171931513  ;;  | -- from the video at:
   1.110 +     4046240009  ;;  | http://www.prb.org/Articles/2002/
   1.111 +     2900237856  ;;  |    HowManyPeopleHaveEverLivedonEarth.aspx
   1.112 +     3390198215  ;;  |
   1.113 +     5427305000  ;;  |
   1.114 +     2130327622]);; /
   1.115 +  "number of people who existed in the given time periods")
   1.116 +
   1.117 +;; Confirm that the sum of people agrees with that in the video.
   1.118 +(assert (= 107602707791 (reduce + (vals births))))
   1.119 +
   1.120 +(defvar lifespans
   1.121 +  (zipmap
   1.122 +   time-periods
   1.123 +   [33   ;; start-8000BC  \
   1.124 +    22   ;; 8000BC-1      | -- from: 
   1.125 +    30   ;; 1-1200        | http://en.wikipedia.org/wiki/
   1.126 +    32   ;; 1200-1650     /    Life_expectancy
   1.127 +    35   ;; 1650-1750 \
   1.128 +    35   ;; 1750-1850  |-- from:
   1.129 +    45   ;; 1850-1900  | http://www.deathreference.com/
   1.130 +    66   ;; 1900-1950  |    Ke-Ma/Life-Expectancy.html
   1.131 +    66   ;; 1950-1995 /
   1.132 +    70   ;; 1995-2011-------> form:  
   1.133 +         ;;   http://www.prb.org/DataFinder/Topic/
   1.134 +         ;;      Rankings.aspx?ind=6&loc=241
   1.135 +    ])
   1.136 +  "lifespans in years from birth for the various time periods")
   1.137 +
   1.138 +
   1.139 +
   1.140 +;; multiply each time-period's total number of people
   1.141 +;; by those people's average lifespan in years to get
   1.142 +;; the total number of man-years experienced during
   1.143 +;; that period, then add them together.
   1.144 +
   1.145 +(dorun
   1.146 + (map println
   1.147 +      (clojure.contrib.string/split
   1.148 +       #"," 
   1.149 +       (cl-format nil "years of human experience: \n ~R years"
   1.150 +                  (reduce + 
   1.151 +                          (map *
   1.152 +                               (map births time-periods)
   1.153 +                               (map lifespans time-periods)))))))
   1.154 +
   1.155 +#+end_src
   1.156 +
   1.157 +#+results:
   1.158 +: years of human experience: 
   1.159 +:  three trillion
   1.160 +:  three hundred seventy-one billion
   1.161 +:  ninety-three million
   1.162 +:  five hundred ninety-five thousand
   1.163 +:  one hundred eighty-one years
   1.164 +
   1.165 +
   1.166 +
   1.167 +Humans have already collectively lived far longer than the age of the
   1.168 +universe.