Could you light the Superdome with cell phones?Posted by David Zaslavsky on
If you care at all about (American) football, or are trying to pretend you do, you probably saw the power go out during the Superbowl this past Sunday. Half the stadium lights, the scoreboard, and the announcers’ booth, completely out of commission. Hey, did you know there are actually people talking during the game most of the time?
Anyway, one of my friends made an offhand comment about people holding their phones up like candles, but it got me thinking, XKCD-style: what kind of light could you get on a football field from cell phones? Enough to play? Or would you have to give everyone xenon lamps? To find out, we have to delve into the, um, murky world of photometry, the science of measuring the perception of light.
Let’s start with something simple. Anyone who’s familiar with a bit of physics knows about power: the amount of energy per unit time. When you characterize a light bulb as a hundred-watt bulb, for instance, that’s a measure of the power it puts out when attached to the circuitry of a standard lamp. There’s a whole hierarchy of other measurements you can make that are all …