A View from the Back of the Envelope top

People seconds
Scale of some things
People
seconds
Rough Draft

...
100you spending 1 second
101
102a 30 s comment in a 30 person class
103
104
105a 30 person 1hr class | a person work week
106awakeness in a month
107a person work year
108
109a life | 10k person work weeks
10101M people watching a 1hr program
1011a city work day
10121k lives
1013a US people day
1014
10151M lives (a mega life) | a World people day
1016
1017
10181G lives (a giga life)
1019
1020~total Homo Sapien seconds
10211T lives (a tera life)

Landmarks

world people seconds per day - 0.5 × 1015 (±5%?)
half a mega life

human life expectancy - two gigaseconds (Gs) (2 × 109s, [...do error bars...])

The back of my envelope...

Life expectancy
~70 yrs ~= 2 × 109 s.
(50,80) yrs ~= (1.6,2.5) × 109 s

A class
30 people for 1 hour = 1 × 105 people-seconds.

Creating a person
0-4mo: 1.1 × 107 s x [1, 2]
4-9mo: 1.3 × 107 s x [1, 2]
0-2yrs: 6,3 × 107 s x [1, 2]
2-5yrs: 9.5 × 107 s x [1, 2]
5-20yrs: 4.7 × 108 s x [1, 2]
So just 20yrs ~= 109. Eh.
Would be more interesting to do with `productive time', ie sans sleep/eat/maintenance.

7 hour day
7 x 60 x 60 ~= 2.5 × 104 s

people seconds / day
5.7 × 109 x 8.6 × 104 = 4.9 × 1014
Say 0.5 × 1015 people-seconds/day (±<5%?).

A View from the Back of the Envelope
Comments encouraged. - Mitchell N Charity <mcharity@lcs.mit.edu>