{"id":5154,"date":"2023-12-15T17:02:08","date_gmt":"2023-12-15T17:02:08","guid":{"rendered":"https:\/\/www.betrisey.ch\/synchronisations-de-3-pendules-de-foucault"},"modified":"2025-01-28T06:49:20","modified_gmt":"2025-01-28T06:49:20","slug":"synchronisations-de-3-pendules-de-foucault","status":"publish","type":"page","link":"https:\/\/www.betrisey.ch\/en\/synchronisations-de-3-pendules-de-foucault","title":{"rendered":"Synchronisation of 3 Foucault pendulums"},"content":{"rendered":"\n\n

Improbable experiment posted live….<\/strong><\/p>\n\n\n\n\n\n

The idea for this experiment came to me in 2002 in my studio when I saw two Foucault pendulums hanging from the same concrete ceiling, their rotations remaining perfectly synchronous for a whole month.<\/strong> They had been doing this for perhaps a year without me noticing. This couldn’t have happened by chance, so what was the law that made them rotate together?<\/p>\n\n\n\n\n\n

So here was a triple experiment to synchronise the rotations of small Foucault pendulums swinging freely against the same wall, the aim being to discover what would happen between the 5 choices available when they were initially thrown in the same direction:<\/p>\n\n\n\n\n\n

1) Anarchy<\/strong>: everyone goes their own way, ignoring the other.<\/p>\n\n\n\n\n\n

Or<\/p>\n\n\n\n\n\n

2) Love<\/strong>: they synchronise their rotations and always oscillate on the same parallel plane.<\/p>\n\n\n\n\n\n

Or<\/p>\n\n\n\n\n\n

3) Dictatorship<\/strong>: they start to oscillate in the same plane, then the heaviest one kills the other by successive phases and phase shifts.<\/p>\n\n\n\n\n\n

Or <\/p>\n\n\n\n\n\n

4) Cold war<\/strong>: they choose the plane of oscillation most opposed to the other (90\u00b0 for 2 pendulums, 120\u00b0 for 3 pendulums) and maintain it indefinitely.<\/p>\n\n\n\n\n\n

Or else… <\/p>\n\n\n\n\n\n

5) …<\/strong> There’s something else<\/strong> we’re going to have to find out.<\/p>\n\n\n\n

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Experiment n\u00b01, December 2023 <\/strong><\/p>\n\n\n\n\n\n

This experiment was not as pure as I would have liked because there was also the miniFoucault<\/a> oscillating at the same time in the same room and the three pendulums tested were barely adjusted. Why on earth not set them better before? Simply because it would have taken me a month per pendulum to do it properly and I don’t have three months to waste. Anyway, the experiment went like this.<\/p>\n\n\n\n\n\n

The experiment went like this, with a 15-second video capture taken automatically every hour for a fortnight:<\/p>\n\n\n\n\n\n

Test 1: pendulum 1 & pendulum 3<\/p>\n\n\n\n\n\n

Test 2: pendulum 1 & pendulum 2<\/p>\n\n\n\n\n\n

Test 3: pendulum 2 & pendulum 3<\/p>\n\n\n\n\n\n

Pendulum 1 (left) weighs around 10 kg for a period of one second.<\/p>\n\n\n\n\n\n

Pendulum 2 (centre) weighs about 3 kg for a period of 0.88 seconds.<\/p>\n\n\n\n\n\n

Pendulum 3 (right) weighs about 6 kg for a period of one second.<\/p>\n\n\n\n\n\n

3 Raspberries, 1 Mac, a Siemens Logo as orchestra conductor. Behind the scenes: a real mess…<\/p>\n\n\n\n\n\n

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