Given that average life expectancy is somewhere between 25,000 and 30,000 days, I suppose it's almost guaranteed that I'll find myself involved in a few "no chance it'll happen" moments before my time here is up. We just live too long, you know? I'll put it this way - if something has a 0.00004% chance of happening on a given day, then that means there's a pretty good chance it'll happen at least once over the course of an average lifetime.
These stray thoughts cross my mind when I realize that very well designed systems have minimized the odds of a problem to what the non-math folks would describe as "no chance it'll happen". One such example is returning a book to the library. I’ve returned close to a thousand books since graduating college and each time the system has worked perfectly – I bring the book to the library, leave the item someplace ‘official’ like a bin or a counter-top, and a day later the book is closed out of my account. This system worked perfectly every single time I participated in it over the last decade. And yet, during certain idle moments, I’d wonder about that day in the future. What if the book fell out of the bin? What if someone snatched it from the counter-top before the librarian? What if the power briefly went out just as the book was being scanned? What if the scanning system went haywire and marked a different book as returned? Regardless of the exact detail, the end result would be the same – I’d be stuck having to find some way to return a book I’d already returned.
Naturally, this long-feared situation finally happened just a few months ago after I finished Amanda Stern’s Little Panic. I returned the book to the library on my lunch break and went about my life for a few days without giving the matter a second thought. When I logged into my account to request a few new books, I found Little Panic staring back at me. I'd returned it a week ago and it was due in seventeen days. How fitting, I suppose, that the book in question was Little Panic, for my reaction was the same uncomfortable mixture of anxiety and confusion that Stern writes so masterfully about in her book. I wasted significant time and energy over the next couple of days having this pointless problem weighing down my mind before I finally acknowledged that the only thing to do was to go to the library, explain the situation, and ask for help.
I went to the library the next day and explained the situation. After a couple seconds of deliberation, the man at the desk announced I was ‘all set’ and sent me on my way. All set? What the heck does that mean, I wondered? I never did get a good answer. Maybe he knew from experience that these books have a habit of turning up, eventually, or maybe he just didn’t care about doing more because closing the book from my account was the easiest resolution. It’s possible he’s still deep in the stacks somewhere, looking for the lost copy of Little Panic. I guess there’s no way for me to know for sure. I just hope the question of this book isn’t weighing down some corner of his mind and bringing needless anxiety into his life because this is like most problems I've spent time worrying about - in the end, I've learned that it was never worth worrying about it at all.
Endnotes / the cutting room floor...
0. Turned out, the math didn't work on this one...
My original draft included the ATM as another example. Someday, this modern marvel of banking efficiency is going to go haywire and start spitting extra money into my greedy palms, right? Like, what could the odds of that happening on a given day be? There's no chance of this happening today, or tomorrow, or on any specific day. If I go to the ATM around three times a month, I should like my odds that this will have to happen someday while I'm making a transaction, right?
When I did the math, I realized that I'd fallen for a basic trap - I considered the odds of something happening on a given day equivalent to the odds it might happen to me. That's not really the same thing (and especially in the context of this post) and since I didn't really need another example, I buried it here instead.
The broad point is more important - nothing designed by humans maintains its perfect record forever. The ATM system, no matter how well designed, is still designed by humans - it's going to fail sometime. It just probably won't involve me standing in front of one, trying to catch the cash flying out of the broken thing...
