ntury chemistry. Nor can it be conjured up by infusing matter with energy, such as a bolt of electricity, à la Dr Frankenstein. There is no life force over and above normal intermolecular forces.
Instead, the living cell is best thought of as a supercomputer - an information processing and replicating system of astonishing complexity. DNA is not a special life-giving molecule, but a genetic databank that transmits its information using a mathematical code. Most of the workings of the cell are best described, not in terms of material stuff - hardware - but as information, or software. Trying to make life by mixing chemicals in a test tube is like soldering switches and wires in an attempt to produce Windows 98. It won't work because it addresses the problem at the wrong conceptual level.
The approach pioneered by Miller is bottom-up, synthesising the building blocks of life from inorganic substances and then trying to assemble them into more complex structures. Meanwhile, molecular biologists have been making strides with a top-down approach, breaking apart the innards of bacteria and viruses, and reassembling the components. Just last month, Craig Venter, famous for his pioneering work on the human genome project, announced his intention to create a brand new life form. Venter plans to strip down and reconstruct the genome of Mycoplasma genitalium, a primitive microbe that inhabits the genital tract.
But this isn't making life so much as rearranging it. Even a simple bacterium is a vast assemblage of intricately crafted molecules, many of them elaborately customised. Although those specialised molecules are not themselves living, they are the products of living things. Scientists make use of them in their microbial tinkering. In other words, they use the products of living organisms to re-make living organisms. They remain a long way from being able to put together a living cell from scratch.
If artificial life is manufactured, it will be by applying the lessons of information technology and nanotechnology rather than organic chemistry. These are emerging fields, and the principles that underlie them are only dimly perceived. The hottest topic is quantum computation - an attempt to harness the weird properties of electrons and atoms to process information at the molecular level. Here, the concept of information is transformed, and the rules for processing it are different. Quantum computation enthusiasts foresee a leap in processing power if the technology can be made to work. Perhaps this could pave the way to creating life in the lab.
Which leaves us with a curious conundrum. How did nature fabricate the world's first digital information processor - the original living cell - from the blind chaos of blundering molecules? How did molecular hardware get to write its own software? The answer must wait until we understand the nature of information, and the principles that govern its dynamics and complexity.
· Paul Davies is a visiting professor at Imperial College and author of The Fifth Miracle: the Search for the Origin of Life