Crown Splash

There is something inherently satisfying about the sound of a pebble breaking the surface of a pond, so satisfying in fact that a few years ago certain DJs and producers encapsulated, mutated and repeated it to create the global phenomenon of ‘minimal’ techno. Having somewhat passed us by we found the sound more befitting of a misty spring morn, camping lake-side in the yorkshire dales than set in an overcrowded nightclub.

A thoroughly satisfying plonk requires a few certain conditions, calm water, a fairly weighty round pebble and a perpendicular entry path. Physicists at the universities of Valencia and Twente have been studying this plonk and have found that a sonic boom is behind it’s well rounded sound. When the stone enters the pond the first reaction is a cylindrical sheet of water called the “crown splash” which is sent up into the air encircling the falling object. Then the stone sinks and leaves in its wake a cylindrical cavity of air. The water surrounding this then begins to collapse in on it, starting at the centre, and creates an hour glass shape. When this form then collapses the result is a jet of air which shoots up the centre of the ever diminishing cavity faster than the speed of sound creating a miniature sonic boom. This combined with the slap of the the water collapsing in on itself gives rise to that sound synonymous with fishing holidays, walks on stoney beaches and, in cases where the falling object is not necessarily a pebble, certain trips to the w.c.

Burchberry Dogwood

It was in the 1950s that aircraft started to break the sound barrier on a regular basis and it wasn’t until 1969 that Concorde took the first supersonic commercial flight. Seen as a barrier there to be broken, Concorde undoubtably did so in the most grandiose manner; but the aircraft was not however the first human invention to cross the supersonic milestone. In fact this invention came from our cat loving friends the Ancient Egyptians in the form of a whip. The tip or a cracked whip will accelerate to speeds way faster than the 340m/s that sound travels at. For the mathematically minded we can see how the thinning and unfurling whip will increases to faster and faster speeds through the equation E = (m(v^2)) / 2. Something which the archaeological crusader Indiana Jones singularly failed to point out even with his copious use of whip and academic background.

And to find the first living thing to break the sound barrier you must venture into the forest covered Canadian Rockies in search of the Burchberry Dogwood, a small plant which spits its pollen out at nearly twice the speed of sound. The force which this plant generates is more than 800 times greater than that which is experienced by astronauts as they leave the earth’s orbit.

Nowadays unmanned craft and missiles can travel upwards of 20 times the speed of sound. Although pioneers in their own right, the designers of the weapons, the masterminds behind Concorde and minimal techno DJs are merely following in the footsteps of ejaculating plants.