Haunted Doors and Murphy's Law
As most of the world knows, January 1989 brought Alaska a spell of what lore-makers would call a Great Blue Cold. While the bottoms fell from thermometers, hardy reporters flocked north to tell the rest of the world about the phenomena of ice fog and square tires, frostbite and hypothermia.
They missed a good one. None of them reported on the haunted garage doors.
This was the scene played out many times in urban Alaska during that cold spell. Home from work drives some hardy soul, braving ice fog and fears of brittle fan belts. The garage door appears dimly through the gloom, the finger leaves the mitten, pokes the button on the door's remote control, and--nothing happens. The driver grumbles, worries about frozen mechanisms, waves the control gadget about, finger still on button...and eventually the recalcitrant door rises. Safe at home, the driver forgets the whole incident as just one more of the almost-problems that get lost in the string of real problems besetting everyone at fifty below.
Meanwhile, miles away, a garage door slowly lifts. Down the block, another creaks upward. The driveways are empty. There are no signaling devices in sight, perhaps no cars. Still, here and there, doors open.
It may seem like gremlins, but it's really the laws of physics operating here--with perhaps just a touch of Murphy's. Indeed, cold affects machinery; yes, just a little frost can louse up electronics. Worse, the atmosphere can start playing tricks with radio waves. The garage doors did not open by themselves. They did receive radio waves of the correct frequency to activate their motors, but those waves may have bounced in from an entirely different transmitter some distance away.
Some of the bounce effect may be produced by the ionosphere, the layer of the earth's atmosphere too high (at least 60 miles up) to be breathable, but laden with electrically charged particles. Because of those particles, the ionosphere can reflect radio waves.
At high latitudes, the ionosphere is especially susceptible to conditions on the sun, because here Earth's magnetic field pulls in particles the sun casts out. A stormy sun casts more particles into the solar wind.
Captured by our planet's magnetic field, the particles rush into the ionosphere, making it churn and warp with the new energy. When the ionosphere is calm, it reflects radio waves in predictable ways, but when it's disturbed, it can bounce radio waves every which way.
Radio-controlled garage doors operate on frequencies of 290 to 440 megahertz (million cycles per second). That part of the electromagnetic spectrum isn't uniquely assigned to garage doors, so people with powerful radio-controlled model airplanes have been known to send the neighbor's doors flapping up and down. For that matter, garages on the flight paths of airports have been subject to fits of spontaneous opening.
Normally the devices operate properly, ignoring extraneous signals. The incoming waves must be of the right frequency, arriving in the proper direction, and strong enough to trigger the radio-controlled switch. That's usually sufficient to guarantee proper operation, but not when the ionosphere is wobbling about severely.
Then there are the radio-propagation games played by the troposphere, the breathable layer of the atmosphere. When it's very cold and a strong inversion develops, so that the hills are much warmer than the valleys, other local signals operating near garage-door frequencies can be bent or bounced from their path. Garage doors then can receive stray radar signals, military communications, all manner of normally unnoticed broadcasts.
That's where Murphy's Law and its corollaries came in. Garage door openers, like every other device, can go wrong. Naturally, bitterly cold weather is when their owners would least like them to go wrong. And that, coincidentally, is when the troposphere can become unreliable. Furthermore, during our cold spell the sun turned stormy and put wobbles in the ionosphere. Thus the scene was set for some stray radio-wave signals to come in at the right frequency, right strength, and right direction to open a few radio-controlled doors--starting reports of a new mystery of the Arctic, one that this article may have helped solve.
