Thursday evening, I had an odd experience on my ride home on the subway. I was sitting on a crowded E train, next to a middle-aged white woman who was sound asleep. It’s always amazed me when someone manages to fall asleep on a crowded subway train during rush hour. Somewhere along the ride, the woman’s wristwatch alarm went off with the standard Casio digital beep. She didn’t wake. The alarm kept beeping, and for a moment, I was scared. I could feel the fear from the people around me on the train, as well. A simple, beeping wristwatch on a crowded train. Was this a portent of death?

If you’re reading this, you know the ending. Nothing happened. The watch stopped beeping, the woman kept sleeping, and everyone around her returned to their own world. Even I forgot about the incident until I got home, and had a chance to breathe and think back on my day. I had to think about this. I’ve lived in New York City for only nine months, but I’ve been a city dweller for the majority of my life. There are more likely threats than a subway bomb, and I know it from experience. One Christmas Eve, on the subway in Philadelphia, I was the victim of an attempted mugging for my phone. [1] Why, then, should a beeping wristwatch alarm scare me, or anyone else on the train?

The Casio F–91W is ubiquitous. An inexpensive digital watch, with classic styling. I’ve owned three, once because they’re cheaper to replace than spend the effort to replace the band. The Casio F–91W is also easy to turn into a timer for an improvised explosive device. The bombs used in the London subway bombings in 2005 didn’t use watch-based detonators, but it’s not impossible for a future attacker to try it. I don’t know how many of my fellow passengers knew what I knew, but the shared moment of fear as the alarm beeped confirmed that my paranoia wasn’t exclusive.

The denizens of any dense, urban environment go about their day living in their own little bubbles. We’re all less worried about the threats to our lives as we are about the little threats: if we can make the rent, if our boss is planning to fire us, if tickets to that show are sold out. We don’t think about the possibility that something could happen to us, by accident or by malice. We’re inured to the idea of our own safety. Perhaps this is for the best. We could be afraid of anything, but we choose not to be. It takes something serious to pop that bubble. If something does, and it turns out to be a false threat, it hones our sense of what to really be aware of.

I choose not to live in fear. I don’t always succeed.