A self-duplicating machine coupled with a computer simulation of a cancer cell and suddenly it would need a thermonuclear device to stop it. My point is that while it is certainly within the realms of possibility, it may be far outside the realm of a rational thing to do. On some occasions the potential for harm is so great that an activity must be halted. This offers the potential of being one of those times.
It isn't scary at all, because it is so limited. It can approximate what a single protein can do, but at a huge scale. It would take a city sized machine made up of these things to imitate the self-duplicating behavior of a cell that might be able to reproduce them. And a lot more brainpower to come up with the structure of the machine and the programming equivalent of the DNA sequences to make it all work.
Where I see this is most useful is to help people visualize what goes on inside a living cell and start to realize just how amazing a nano-scale machine it really is, and what it would take to make such a thing work.
It is a bit scary to me! I don't like the idea of machine reproduction as I wonder it ultimately will be out of controlled (at least most people couldn't). Frankly, I think the technology is moving too fast!
I think the philosophers and ethicist tend to show up after the fallout.
First it's the science fiction writers. Then the crazy people. After the crazy people get things going, the business folks coming and try to turn it into a business. If it becomes popular and useful, there's a good chance regulators will come next. Unfortunately, the regulators tend to regulate the safe parts and let the dangerous parts wreak havoc on society.
Finally, those philosophers and ethicists come in and contemplate what we should have done.
one of the beauties of the nature is that each species reproduces exactly its own replica - the shape, the size, the life cycle and everything.
Will the self creating materials follow ( hopefully the bug free software) the rules to the hilt so that there is no anarchy in the world?