Constructing devices or matter at one-billionth of a meter scale, about the width of ten atoms, poses unlimited opportunities and you have cited just a few of them. One of the most promising, perhaps, is the development of miniaturized delivery vehicles for targeted pharmaceutical delivery or the use of micro-surgical cutters. ET End of the world scenarios have been a favorite topic throughout history. Statistically, there are a considerable number of formidable dangers that could threaten devastation of earth, just as they did many millions of years ago periodically in decimating existing life forms. But resilient life forms survived and entire new evolutionary paths were hewn.
Manmade interventions fall on a lesser scale but nonetheless are important.
Statistical probabilities for these kinds of terminal disasters are minimal. ET Media density is something that has enhanced communications over the millennia. The first stone etchings or inlays required about one square inch per character. Today, silicon computer chips are approaching the packing density of one billion transistors by the year 2005. As quantum physics is tapped for digitizing data, existing storage of media will probably increase by as much as one trillion fold.