Candle Flame Oscillations as a Clock

Summary

Todays candles have been optimized for millenia not to flicker. But it turns out when we bundle three of them together, we can undo all of these optimizations and the resulting triplet will start to naturally oscillate. A fascinating fact is that the oscillation frequency is rather stable at ~9.9Hz as it mainly depends on gravity and diameter of the flame. We use a rather unusual approach based on a wire suspended in the flame, that can sense capacitance changes caused by the ionized gases in the flame, to detect this frequency and divide it down to 1Hz. Introduction Candlelight is a curious thing. Candles seem to have a life of their own: the brightness wanders, they flicker, and they react to the faintest motion of air. There has always been an innate curiosity in understanding how candle flames work and behave. In recent years, people have also extensively sought to emulate this behavior with electronic light sources. I have also been fascinated by this and tried to understand real candles and how artificial candles work. Now, it’s a curious thing that we try to emulate the imperfections of candles. After all, candle makers have worked for centuries (and millennia) on optimizing candles NOT to flicker? In essence: The trick is that there is a very delicate balance in how much fuel (the molten candle wax) is fed into the flame. If there is too much, the candle starts to flicker even when undisturbed. This is controlled by how the wick is made. Candle Triplet Oscillations Now, there is a particularly fascinating effect that has more recently been the subject of publications in scientific journals12 : When several candles are brought close to each other, they start to “communicate” and their behavior synchronizes. The simplest demonstration is to bundle three candles together; they will behave like a single large flame. So, what happens with our bundle of three candles? It will basically undo millennia of candle technology optimization to avoid candle flicker. If le...