What is Life?

That's not quite true: hardly any processes take place in a virus itself. One of the characteristics of viruses is that they have outsourced almost all of their chemistry to their host cells. All a virus does is insert its DNA into a host cell. The cell then takes care of the rest.I believe Richard Dawkins said somewhere that life is molecular information technology, and I think he was pretty much on the mark there. Viruses have managed to strip this concept to the absolute bare minimum: molecular information in an envelope able to make sure the information is copied. Other lifeforms have gone to sometimes extraordinary lengths to get the job done, by building enormously complex aggregates of billions and billions of cells, some of which we call elephants, others we call sequoias. But in the end these big bodies serve the same purpose as the simple protein envelopes of viruses: to make sure the DNA inside it gets copied.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Ever since Darwin we know quite well what the driving force behind the increasing complexity of life on earth is: it's Darwinian evolution. This suggests another interesting way of defining life, for which I'll quote Gerald Joyce (look under the heading "Proposed", a bit further down):"Life is a self-sustained chemical system capable of undergoing Darwinian evolution."Whether one could take this one step further and include any such system, not just chemical ones, is a matter of debate. Speaking for myself, I would be inclined to view a computer simulation in the form of a genetic algorithm as genuine evolution, but I would not go so far as to call it life.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.