EPR 52

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A moon phase display where no display should fit: there are challenges in the world that even a genius inventor might have trouble with.

A collector and owner of one of the MIH watches asked Gerber if it might be possible to integrate a moon phase into the caliber for him. Even the talented Gerber had to pass on this idea as the layout of the already existent calendar displays take up the entire surface underneath the dial. But maybe there was a possibility of achieving this if the moon phase display were contemplated separately from the movement. This is how the idea for the micro moon phase EPR 52 began to take root.

The patent-pending micro moon phase EPR 52 pays homage to Einstein, Podolsky, and Rosen with the initials in its name, while the numeral 52 stands for the 52nd caliber that Paul Gerber has conceived, constructed, developed, and built in his forty-year career.

Micro moon phase designed for strap thickness 4 – 4.5 mm, from width 20mm  

Breaking the mold
The extreme miniaturization of a moon phase display wasn’t what puzzled Paul Gerber; it was more the search for the correct positioning of where the mechanism could be placed.

Why not within a small casing that could be placed on the strap, he thought? This way the watch dial would be close without the added moon phase having to take a prominent place on it. Naturally, the compact additional casing would have to offer the mechanism protection from the perhaps negative influence of its surroundings in a place that might get bumped more often, which is why its tiny titanium case is shockproof and water resistant.

Without a connection to the movement of the «mother watch», the moon phase also needed its own time source and its own drive train. As there was no room in the tiny case for a spring barrel and a balance, Gerber once again began to think outside the box: why not use a quartz movement with micro battery?

Quartz technology is in the world of mechanical Swiss watches relatively frowned upon, however this purist taboo feeling is normally aimed at inexpensive products exposed by the «traitorous» jumping second hand visible on the dial. Neither of these arguments have a place in Paul Gerber’s the micro moon phase, though, and using quartz technology solves the space problem elegantly, practically, and reliably.

Gerber’s micro moon phase EPR 52 builds a bridge between two worlds: on one side is the mechanical moon phase display, and on the other the electromagnetic drive. Thanks to quartz technology, this micro moon phase has a power reserve of at least three years, which just about corresponds to the shelf life of a normal leather strap in everyday use. Which means the strap and the battery can most efficiently usually be exchanged at the same time. The case is hermetically sealed and has neither crown nor corrector: correction of the moon phase display is simultaneously undertaken by the watchmaker when he or she changes the battery.


Einstein’s spooky action at a distance
In one way, the micro moon phase by Paul Gerber is an homage to quantum physics, and even more specifically to quantum entanglement, which states that two particles without physical contact can be connected, thereby sharing the same destiny even across great distance – just like the time and the moon phase in this instance. The two displays have no physical connection yet work hand in hand to display the passing of time.

The 1935 EPR paradox – named for the men who discovered it, Albert Einstein, Boris Podolsky, and Nathan Rosen – is a complex conceptual construct that is very difficult to imagine and even more difficult to describe. Einstein himself jokingly spoke of «spooky action at a distance,» and not just a few of his contemporaries treated the EPR paradox with healthy skepticism. However, the Chinese quantum satellite Micius has been orbiting the globe since 2016 with the goal of building a global quantum network whose purpose is to allow tap-proof data transmission. It is based upon Albert Einstein’s idea of «spooky action at a distance.»

Technical data

  • Titanium case Ø 12mm, height 5.5mm, sapphire crystal case back secured by 3 titanium screws, weight 0.8 gr,  waterresistant
  • Moondisc Ø 9mm with 2 polished inserted gold moons (18k)
  • Moon module Ø 10mm,height 0.9 mm, moon advances every 12 hours
  • Powered by modified 5 jewel quartz movement with micro battery.
  • Autonomously for three years
  • Designed for strap thickness 4 – 4.5 mm, from width 20mm 
  • Individually numbered on case back
  • Case made by UhrTeil AG ( Andreas Strehler)
  • Patent pending 


EPR 52 CHF 980.– plus watch strap of your choice


For leather or rubber strap thickness 4 -4.5mm, from width 20mm
(price are subject to change without notice)