A series of six lectures by Professor Colin Blakemore 2: The Sound of Silence
The photosensitive rods in the retina of the eye are so sensitive that they can generate a signal when they catch a single quantum, the smallest unit of light possible. The sun is 10,000 million million times brighter. But our eyes can operate satisfactorily over that enormous range although our senses are passed to the brain over low-quality wires, our nerve fibres.
(The Sixth Sense - and the Rest tomorrow at 2.55 pm)