I seem to have some for of quantum uncertainty watch ...

… or perhaps the polar opposite. It might be the only time it is accurate is when I’m observing it. It’s a Citizen Men’s AT4006-06X watch. Solar powered, “atomic” time accuracy set by radio signals from the Halls of Science somewhere in America, once set I should never have to adjust it again until entropy disables its movement.

I’ve had this thing just a couple of weeks, and I’ve noticed some really odd behavior. I’ll preface this by saying that I’m often wearing a long sleeved shirt or light jacket, and the watch is hidden under the cuff.

Three times now, I’ve pulled back the cuff and seen the second hand of the watch running with frantic speed, until it gets to the correct time and then it resumes it’s normal second to second pace. I know it gets back to the right time, because I’ve checked it against a reference time shortly afterward.

So what’s going on? My logical mind tells me the following is possible, but there is nothing in the documentation to support this theory. First, the speeding second hand is normal behavior for those time when the watch is set incorrectly and it then receives the signal to correct the time. But when that happens – and it’s only happened a couple of times in the first couple of days when I was playing with the controls – the minute and hour hands also fly around at high speeds until it gets to the correct time. But the later sightings have only involved the second hand moving.

So my theory goes that, when light is cut off from the watch face, the second hand movement stops, to save energy, while the minute and hour hands remain at their slower movements. When enough light hits the sensor in the watch face, the second hand is triggered to catch up at high speed to the correct time. So may watch may be unpredictably inaccurate when I’m not viewing it, and only achieve accuracy again when light makes the hands visible.

Either that, or the second hand just randomly stalls out on occasion, and as randomly corrects itself on other occasions. But it’s very odd that I haven’t witnessed such a stall, only correctly kept time, or a speeding hand working to catch up to the correct time.

Any thoughts on this odd behavior?

I also have a little alarm clock, also with a correcting mechanism that listens to the radio (it’s WWV, in Fort Collins, Colorado), but it only sends the signal once every 24 hours, and if there is bad signal (it’s a low power station), it might be another day before it corrects the time (like when Big Brother makes us all switch to daylight wasting time). That radio time signal does not send out correcting time signals readable by clocks constantly, but periodically, and clocks have to wait for them to reset…

Your watch may be powered by a solar cell, that only has enough power to reset when it is lit. So it can still hear and remember the signal, but it doesn’t activate the watch
s hands unless powered up.

If you catch it in the act frequenlly, my guess is that the watch is so inaccurate, it has to correct by several seconds just about every day.

(The above is my guess, based on what I believe I know about them.)

Presumably since it’s solar-powered, it won’t correct itself unless there’s adequate power supply, so the reaction when you expose it to light is easy to understand.

The speeding second hand may be because it only rotates in one direction. The watch may be persistently gaining only one second every few days, but the only way to correct that is to rotate the second hand forward by 59 seconds.

I’m curious. Why only one? Why so low power? And why don’t watches and clocks use GPS satellites instead – I believe they have very precise clocks.

I have a Citizen Eco Drive. Its second hand movement stops to save power when it has no light. If you suddenly give it light you will see the second hand slave to the correct seconds as you have been observing with your watch. This behaviour was described in the manual by the way.

And here it is in the manual for your watch:

It’s actually a reasonably high-power transmitter (70 kW, which is more than most FM stations). But the received signal strength is low because the station covers the whole country. There’s only one because… that’s all that’s needed.

GPS indeed provides a precise time signal, but requires sophisticated and computationally expensive decoding. GPS receiver watches do exist, but they don’t have great battery life, and certainly couldn’t be powered by a solar cell unless the GPS was activated only very rarely.