I've been accused of making good use of back of the envelope calculations, so called because they are historically done on the back of scrap paper like an old envelope. I'm a big proponent of these simple calculations, which often take the form of a kind of thought experiment. They can sometimes change your entire perspective on whatever problem is at hand.
Computer scientist Jon Bentley wrote a column called Programming Pearls for the journal Communications of the ACM, the articles of which were later collected into a book by the same name. He devoted a chapter to back of the envelope calculations. He discussed how to use simple arithmetical techniques to do things like estimate answers to complex questions, do performance estimates, and compute safety factors. Some of the tips he gives for back of the envelope calculations are two answers are better than one (if you arrive at similar answers by following two different paths, you are more likely to be in the ballpark), quick checks (be sure that the magnitude of your answer makes sense in the real world), and (quoting Albert Einstein) everything should be made as simple as possible, but no simpler.
I recently did a simple back of the envelope calculation to do a little self-discovery, and the result surprised me.
Mrs. Overclock (a.k.a. Dr. Overclock, Medicine Woman) and I share a lot of the same tastes in books. We met thirty years ago as college students in a science fiction club. But our literary interests diverge when it comes to fantasy. Yes, I enjoyed Tolkein's Lord of the Rings. Susanna Clarke's Hugo-winning Jonathan Strange & Mr Norrell was probably the best fiction book I read last year. But Mrs. Overclock finds it irritating (to say the least) when I say that when it comes to whatever latest epic fantasy she's reading, life is too short. My friend Tamarra Noirot, who is also an avid science fiction and fantasy reader, says that I am just not sophisticated enough to appreciate a good alternate history fantasy dragon story. She's undoubtedly right.
But to put things in perspective, let's do a back of the envelope calculation.
I am fifty-one years old. I have maybe twenty more productive reading years left in me. Could be more, but it's not likely to be decades more. Could be less, particularly if I keep pursuing hobbies of potential lethality. But twenty years is a good upper bound. And choosing the number twenty, rather than twenty-one or nineteen, makes the math easy and will yield an answer that is close enough. Doing something like trying to calculate my expected longevity using actuarial tables is way too much work and definitely not in the spirit of the back of the envelope, not to mention completely unnecessary.
I read a lot. In a year, I read about twenty books. Some years more, some years less. Of course, I read a lot more than just those twenty books. I read most of BusinessWeek and Newsweek every week, and just about all of Esquire, Wired, and Dr. Dobbs every month. I also read the occasional motorcycle and shooting magazine, as well as perusing IEEE technical journals, white papers, the occasional article in Harvard Business Review, and a slew of blogs I subscribe to via Google Reader. Can't miss any of Stuff On My Cat. But twenty books a year is in the ballpark.
Twenty years times twenty books a year yields four hundred books.
Of those four hundred books, about half will be fiction. The other half are non-fiction books like Freakonomics, Blink, The World Is Flat, or Peopleware. That leaves two hundred fiction books.
Of those two hundred fiction books, about half will be speculative fiction. The other half are other genres like mainstream or detective novels. I'm partial to Robert B. Parker, but I also read bestsellers like, recently, Special Topics in Calamity Physics and The Road. (The Road won the Pulitzer Prize, but it's not the feel good book of the year, unless the image of babies turning on a spit over an open fire makes you feel good. It's the kind of book that leads you to suddenly see the wisdom in a gun safe full of tactical weapons in your basement.) That leaves one hundred science fiction books.
One hundred science fiction books. Maybe more, but not ten times more, probably not even twice as many. Maybe less. Maybe a lot less. One hundred science fiction books spread out over the rest of my entire life.
When I arrived that estimate, it was a sobering revelation. No wonder I'm so damned picky about who and what I read. Life really is too short to read stuff I'm not really interested in.
Through a similar back of the envelope calculation, I can arrive at the conclusion that life is also too short to do work that I'm not really interested in, or not really good at, or spend time in a job I don't really love. It's too short to spend any of it with people I don't like. Bob Sutton arrived at the same conclusion through a different route in his latest book, The No Asshole Rule. Unless you happen to be immortal, a similar calculation will apply to you.
I'm currently reading The Three Musketeers by Alexandre Dumas. First published in 1844, it is a classic that has stood the test of time. Three hundred and ninety nine more to go.
Cardinal Richelieu is my role model.