keithl wrote:...There is another error in the calculation - 80 column punch cards only stored 1 of 64 symbols per column - the coding was sparse, 6 bits of information per column! The newer 96 column cards (which never really caught on) had denser coding ... Imagine telling a 1960's atmospheric scientist that you were about to "burn" 15 exabytes of data. If they believed you, they would kill you to stop you.
The cards are capable of handling more than 3 punches in a column, though, e. g. for binary.
Also, I think your estimate that card stock is as dense as water, and that all the carbon therein would become atmospheric CO2, is a bit high. Also, were 1960s atmospheric scientists especially concerned about CO2?
Please give an example of an 80 column card punched as you suggest. The 96 column cards indeed could be punched into binary lace, but the handling machinery was a lot more sophisticated and expensive, and thank goodness we went to disk packs and text terminals before those became widespread. The 80 column cards were stouter, and quite heavy; in my early teens I handled a few 2000 card boxes. Cards were pulled through readers and past mechanical contact switches at fairly high speeds and accelerations; a hypothetical card with all columns punched would simply tear in half and jam the reader. You could make such a card (pretty!) by running it through a keypunch multiple times. Submitting one in a card deck and jamming the reader was one way to sabotage a 1960's data center.
Another way was to wet the card and soften it, then go over it with a clothes iron to partly close the holes. Both were popular pranks among the anticorporate counterculture; utility bills were often printed on punch cards. Of course, the suits on the top floor weren't affected by these pranks, just the poor overworked schlubs in the basement machine room. My single mother was one such schlub.
Nope - normal 80 column cards had only 0 to 3 punches, for mechanical reasons. Even then, the readers were finicky and failed a lot; moisture would stick two cards together, lint from the cards would accumulate and jam the gears, etc. They used mechanical contacts because lint plugged up optical paths, and phototransistors weren't available.
Concern about CO2
and atmospheric warming? Demonstrated by Tyndall in 1860, numerically calculated by Arrhenius in 1896. The Mauna Loa CO2
measurements begin in 1958, and show an annual monotonic trend through the 1960's. While warming from atmospheric CO2
became a cause célèbre with Hansen's 1981 congressional testimony, the science was almost a century old. It's a pity most people (deniers and fearmongers alike) still don't understand Arrhenius's reasoning.