ABSTRACT
Nobody knows how life works. Neither physicists nor chemists have ever been able to make a living object from non-living matter. The theory of evolution, initiated by Charles Darwin in the 1800s and developed by innumerable biologists since, envisages life beginning, somehow, as single microscopic 'cells' a few billion years ago. In a human being, some growing cells turn into brain cells, some become stomach or liver cells, and so on. In the early part of the 1900s, the brain was often compared to a telephone exchange. These days, preferred technical analogy is with the digital computer. The brain is digital in the sense that its billions of brain cells exchange digital nerve pulses among each other, and that these pulses seem to convey information by their number or frequency, and not by their intensity or duration. The brain probably has many other tasks than storing and handing data, and again, that lack of precision ought to help.
