Five metronomes, two empty drink cans and a physicist have combined to create a surprise internet hit.
A video of a strangely mesmerising experiment by Alireza Bahraminasab has been watched more than 1.2 million times on the video-sharing site YouTube. It is now the site's top rated and most discussed UK education video.
The one-minute clip starts with Dr Bahraminasab, a physicist at Lancaster University, setting off five metronomes, which tick away in unsynchronised fashion.
He then places them on a board balanced so that it spans the gap between two cans on their sides.
Slowly the metronomes start to synchronise until, less than a minute later, they tick away in unison.
Dr Bahraminasab said the demonstration sheds light on a concept that is found commonly in nature, as well as in man-made structures such as London's famously bouncy Millennium Bridge.
"If you put the metronomes on the steady table, the metronomes do not realise each other's vibrations. But if you put them on the empty cans, because of the movement in the base, they synchronise very quickly," he said.
"This happens often in nature. For example, if you record the voice of crickets and then play it to other crickets, they start to sing in time with the recording.
"Another example was when the (pedestrian-only) Millennium Bridge opened and the people walking over it created vibrations. Although they were walking randomly, the small interaction they had made the whole bridge resonate."
Dr Bahraminasab, a postdoctoral research associate, said he has been surprised by the popularity of the video.
He put its success down to the simplicity of the experiment.
"Anyone can understand it, and it's entertaining and short too. That's the only way I can explain its popularity. A lot of people also said they found it quite hypnotising."