From flashing fireflies to cheering crowds — Physicists unlock secret to synchronisation

Physicists from Trinity College Dublin have unlocked the secret that explains how large groups of individual “oscillators” – from flashing fireflies to cheering crowds, and from ticking clocks to clicking metronomes – tend to synchronise when in each other’s company.

Their work, just published in the journal Physical Review Research, provides a mathematical basis for a phenomenon that has perplexed millions – their newly developed equations help explain how individual randomness seen in the natural world and in electrical and computer systems can give rise to synchronisation. 

We have long known that when one clock runs slightly faster than another, physically connecting them can make them tick in time. But making a large assembly of clocks synchronise in this way was thought to be much more difficult – or even impossible, if there are too many of them.

The Trinity researchers work, however, explains that synchronisation can occur, even in very large assemblies of clocks.

Dr Paul Eastham, Naughton Associate Professor in Physics at Trinity, said: 

“The equations we have developed describe an assembly of laser-like devices – acting as our ‘oscillating clocks’ – and they essentially unlock the secret to synchronisation. These same equations describe many other kinds of oscillators, however, showing that synchronisation is more readily achieved in many systems than was previously thought.

“Many things that exhibit repetitive behaviour can be considered clocks, from flashing fireflies and applauding crowds to electrical circuits, metronomes, and lasers. Independently they will oscillate at slightly different rates, but when they are formed into an assembly their mutual influences can overcome that variation.”

This new discovery has a suite of potential applications, including developing new types of computer technology that uses light signals to process information.

The research was supported by the Irish Research Council and involved the Trinity Centre for High Performance Computing, which has been supported by Science Foundation Ireland.