Getting in sync can be exhilarating when you’re dancing in rhythm with other people or clapping along in an audience. Fireflies too know the joy of synchronisation, timing their flashes together to create a larger display to attract mates.
Synchronisation is important at a more basic level in our bodies, too. Our heart cells all beat together (at least when things are going well), and synchronised electrical waves can help coordinate brain regions – but too much synchronisation of brain cells is what happens in an epileptic seizure.
Sync most often emerges spontaneously rather than through following the lead of some central timekeeper. How does this happen? What is it about a system that determines whether sync will emerge, and how strong it will be?
In new research published in Proceedings of the National Academy of Sciences, we show how the strength of synchronisation in a network depends on the structure of the connections between its members – whether they be brain cells, fireflies, or groups of dancers.
The science of sync
Scientists originally became interested in sync to understand the inner workings of natural systems. We have also become interested in designing sync as a desired behaviour in human-made systems such as power grids (to keep them in phase).
Mathematicians can analyse sync by treating the individuals in the system as “coupled oscillators”. An oscillator is something that periodically repeats the same pattern of activity, like the sequence of steps in a repetitive dance, and coupled oscillators are ones that can influence each other’s behaviour.
It can be useful to measure whether a system of oscillators can synchronise their actions, and how strong that synchronisation would be. Strength of synchronisation means how well the sync can recover from disturbances.
Take a group dance, for example. A disturbance might be one person starting to get some steps wrong. The person might quickly recover by watching their friends, they might throw their friends off for a few steps before everyone recovers, or in the worst case it might just cause chaos.
