From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of John Denker
Sent: Wednesday, December 18, 2013 4:16 PM
To: Phys-L@Phys-L.org
...
> In that spirit, we consider the hypothesis that the bulbs are up in the ceiling,
> out of reach, and that they are LED bulbs anyway, so they don't heat up.
> This means that the hot/warm/cold strategy suggested by Chris Gould --
> which is an excellent strategy under other conditions -- does not work here.
I've never been in a house where the lights were inaccessible. If they were, how would you ever replace them when they burn out? And LED bulbs _do_ heat up -- just not as much as incandescent bulbs. But I digress.
If you insist on playing by the rules (i.e., information consists solely of "in band" data: switch states and bulb states) then you are, of course, correct. You can't solve the problem in one traversal of the stairs.
My solutions (and Jeff Bigler's clever use of a fourth light bulb) used "out of band" data (temperature, voltage, brightness) to increase the number of bits of information, solving the problem. In a different context that's called thinking outside of the box. Can't do that in physics class. :-) But as you said, this was "just for fun."
_________________
Christopher M. Gould 213-740-1101 Dept. of Physics & Astronomy
gould@usc.edu Univ. of Southern California http://physics.usc.edu/~gould/ Los Angeles, CA 90089-0484