Alarm clocks are temporal. They tell you when some time criterion has been reached. They’re very useful.
But often, I really want an alarm with a spatial criterion – a location alarm. Let’s consider some possible uses:
- Beep shrilly if anyone tries to steal this device from its current location. [I think there are accelerometer-based programs for laptops that do this]
- I’m snoozing on the train – wake me up when we get near Penn Station. [This is where I first came up with the idea].
- Give me a kick if I’m still in my office when I’m supposed to have left for that meeting. After all, I don’t need the alarm to go off if I’m already on my way to the meeting. [though that's a combination space + time criterion]
This would make for an obvious and delightful iPhone app. I haven’t found one yet, but I haven’t looked hard either.
UPDATE: there are some really superb suggestions in the comments, and in Hacker News that take this idea much further. I particularly liked these:
- R.J.: Google Maps needs this so when I’m walking down the street I don’t have to pay attention to street address numbers/keep my eyes glued to the screen.
- Frankus: Maybe something like that could tell me when I’m close to the grocery store that I need to buy milk.
- Frankus: A game where you try and assassinate your friends by setting imaginary time bombs to go off at a particular location when you think your friend will be there.