Serendipity strikes again !

As is well-known, many of the major discoveries in science have been serendipitous - most famously Alexander Fleming's discovery of penicillin.

A group in Britain has shown that forgeries of paper documents, plastic cards etc can be detected by using a simple laser scanner. The method, published in the latest edition of Nature, takes advantage of the fact that almost all documents 'contain a unique physical identity code formed from microscopic imperfections in the surface'. This fingerprint can be read by using the phenomenon of laser speckle (in lay terms, scattering of laser light from a surface) with an appropriate scanner. The biggest cost-saving from this technology would be not having to impart an external security tag such a hologram, watermarks, microchip etc. to important documents, currencies, credit cards etc.
So why the title ? As this report on NPR Morning Edition mentions, the researchers were actually scanning a new security chip they had developed, which fell off, exposing the paper underneath it to the laser. To their surprise they found a signal coming from the paper - further investigation led to the discovery that each piece of paper has its own unique 'roughness' and hence an unique signal !