Post Script.
As a spinning coin, or disc, begins to fall flat it rattles with increasing speed until it abruptly stops. This may seem unremarkable enough, but scientists have struggled to explain why it happens.
Yesterday a Cambridge University mathematician provided the solution - and revealed a link between spinning coins and Black Holes.
In a bewildering flurry of equations, Prof Keith Moffat showed that the phenomenon was caused by the thin layer of air between the disc and the table.