A lesson learned by centuries of beachcombers has been distilled to a physicist's formula: to make the perfect sandcastle, use eight parts sand to one part water.
The physicists' study, released before publication in the journal Nature Physics, is entitled, rather grandly, 'Maximum angle of stability of a wet granular pile'.
While it deals with sandcastles, it could also help determine the stability of retaining walls and the material they hold back, one of its authors said.
This study and those that follow on this subject might have implications for those preparing for or recovering from a watery disaster like a hurricane, physicist Arshad Kudrolli said.
'Our study is the first step, in some sense, in trying to understand what's the most stable angle that one can build, say, a retaining wall,' he said. 'And if it fails, where would the material end up? How much part of the land will give way?'
Inspired by childhood memories of the seaside, the study's authors worked on a simple model of what makes for the most stable construction involving liquid and particles.
In the case of a sandcastle, builders need to use roughly one-eighth the water to the amount of sand, though Mr Kudrolli said there is a range of possibilities that would work.
Quicksand myth exposed
Quicksand is not the bottomless pit portrayed in Hollywood films that sucks in unsuspecting victims and swallows them whole. It is true the more people struggle, the deeper they sink into the soupy mixture.But its buoyancy makes it impossible to be completely submerged, scientists report today in the journal Nature. 'Everybody thinks, thanks to Hollywood, that you can drown in quicksand. Basically if you do a simple buoyancy calculation, the Archimedes force, it is immediately evident that you can't drown completely,' says Professor Daniel Bonn, a physicist at the University of Amsterdam.Quicksand consists of salt, water, sand and clay. It is the water content that makes quicksand, which is found near estuaries, beaches and rivers, so dangerous.
This important research has significant rhetorical, domestic and foreign policy implications. George Bush, despite charges that he's all hat and no cattle, loves Western metaphors, like getting Osama bin Laden dead or alive (give or take a delay longer than separates Pearl Harbour and VJ Day). He also loves saving money on flood protection. Now if you can't drown in a quagmire... And if you can build a levee bank that's 8 parts sand...