A Look at the Femtosecond and Where to Find a Device Capable of Measuring It

A Look at the Femtosecond and Where to Find a Device Capable of Measuring It

Somewhere in La Chaux-de-Fonds, at an altitude of 1000 metres in the Jura mountains, an infinitely small measurement device has been housed in the heart of the only international watchmaking museum in the world.

By Joël A. Grandjean

People love to talk about what they haven't seen and never will. Thus we speak of galaxies, stars that take us from the top of their thousands of light years, to atom particles that divide again to infinity after we locate them.  In short, however insignificant it might be, the femtosecond, aka one quadrillionth of a second is something worth studying. Particularly, a unique unit which will be hustled in 3,600 units in one hour, is in the spotlight at the top of the Canton of Neuchâtel thanks to a media-ludic premiere: house in a room of its own.

Some clarifications about accuracy

The quest for precision has occupied watchmakers and scientists ever since the consciences of peoples have taken on temporal perceptions. As far as what concerns us most, namely mechanical watchmaking, this quest has generated a large number of innovations since the 17th century.

"Oscillators are at the heart of these developments: the pendulum, the balance-spring and then quartz made it possible to increase the precision of clocks tenfold" says Régis Huguenin-Dumittan, the MIH’s Curator.

Suddenly, the precision of time changes tack: at the end of the Second World War, the precise measurement of time passed from the camp of watchmakers and astronomers to that of physicists. Since 1967, the second is no longer defined by astronomical observations as the passage of the Sun at its zenith, but by the measurement of a microscopic phenomenon: the oscillation of cesium atoms. Since then, progress has been made to boost creativity, research and therefore discoveries. Thus it is possible to assert that the imprecision at the beginning of our third millennium, which is equivalent to the margin of error of a cesium ticking, is in the order of 0.000 000 000 000 001 second, or one femtosecond.

From Henri Grandjean to the micro second, History in motion

In La Chaux-de-Fonds, where the history of watchmaking has so influenced the architectural and human reliefs that Unesco has echoed it in its world heritage of humanity, this incredible museum stemming from private companies is the vision of a builder, Maurice Ditisheim. Allowing students and enthusiasts alike, scientists and neophytes alike, to remember that not so long ago, the clocks on the bell towers indicated only the hours and that it took a little while before minute and then second hands decided to sweep our dials.

This contextualization, this leap into the past to better grasp a future that gives vertigo, opens up a field of dreams and possibilities, one of the most tangible representations of which today in the collective consciousness remains the Galileo satellite whose existence nestles in the nooks and crannies of our smartphone. Then, at the end of the visit of this exhibition, other words will enrich the time vocabulary: like cesium, hydrogen or rubidium... Enough to delight, if he had had the possibility to attend, the initiator and the builder of the Neuchâtel Observatory, my ancestor, the great watchmaker Henri Grandjean. This exceptional man, who ten years later, in the name of the quest for precision, linked the watchmaking school of Le Locle to this Observatory whose large meridian telescope still echoes today the Oscillatom, this cesium atomic clock developed by the Oscilloquartz company in Neuchâtel.

In La Chaux-de-Fonds, time has a date with History. Together, they have plans for the future. And, contrary to the daring comparison recently made by Xi Jinping, the President of China visiting these walls, the MIH International Watchmaking Museum, is nothing like a Forbidden City.

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