"Oh, your watch is beautiful! Is it...?" "Atomic," you'll be able to say very soon, if you have a huge amount of money and don't mind wearing radioactive matter about your well-tailored person.
Hoptroff, the London-based makers of the intricate insides of personal timepieces, have teamed up with time techies Symmetricom to make what they call the No 10, "the world's first atomic-powered pocket watch".
Hoptroff says it's the most accurate movement ever, losing one and a half seconds every thousand years -- that's 240,000 times more accurate than Big Ben.
Not to be confused with your common or garden watch that might achieve that kind of millenial accuracy by simply receiving a radio signal from a central atomic clock -- like this Hammacher Schlemmer effort -- the No 10 has all the gubbins it needs to do the job itself.
Indeed, Symmetricon developed the chip-scale atomic clock system for the US military, which needed self-reliant super-accurate timepieces in case of signal jamming. And because of the scary stuff inside it, you'll be subject to security clearances before you can buy one.
The movement contains a tiny caesium gas chamber inside a temperature-controlled oven, with a laser to activate the radioactive atoms and a microwave resonator to measure their atomic transitions -- their half-life -- in order to measure time.
"As far as we know it is the first time an atomic time source has been used in a pocket watch movement," boasts Richard Hoptroff, managing director of Hoptroff, "and it delights me that it was achieved right here in London, not Le Locle or Tokyo."
The movement has a staggering 28 dials, measuring useful things to know such as your longitude, latitude and humidity, and whether the mini nuclear reactor is about to tear a hole in your abdomen.
The finished pocket watch is due later this year, and will cost "well into five figures". Only 12 will be made. Here's a concept design of what it might look like:
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