Английский язык: Аннотирование и реферирование текста

289 cally relies on plants full of large, pressurized tanks of chemicals. Not surprisingly, these occasionally spill, explode, or burn. With nanotech- nology, chemical plants will be unnecessary because molecules can be transformed in smaller numbers, as needed and where needed, with no need for high temperatures, high pressures, or big tanks. This will not only avoid polluting by-products, but reduce the risk of accidents. How to Prepare a Big Mistake The so-called "Star Trek scenario" (named after an episode of Star Trek : The Next Generation that featured runaway "nanites") is perhaps the most commonly imagined problem. In this scenario, some- one first invests considerable engineering effort in designing and build- ing devices almost exactly like the one just described: bacterial-sized, omnivorous, able to survive in a wide range of natural environments, able to build copies of themselves, and made with just a few built-in safeguards – perhaps a clock that shuts them off after a time, perhaps something else. Then, accidentally, the clock fails, or one of these dan- gerous replicators builds a copy with a defective clock, and away we go with an unprecedented ecological disaster. This would be an extraordinary accident indeed. Note well, though, that this accident scenario starts with someone building a highly capable device that is almost disastrously dangerous, but held in check by a few safeguards. This would be like wiring your house with dynamite and relying on a safety-catch to protect the trigger: a subse- quent explosion could be called an accident, but the problem isn't with the safety mechanism, it's with the dynamite installation. Do we need to build nanotechnological dynamite? It's worth con- sidering just how little practical incentive there is for anything even resembling the dangerous replicator just described. (Note that our topic here is accidents; deliberate acts of aggression are another matter.) How to Avoid It With our present technology, which is simpler to build – a car that runs on gasoline, or one that forages for fuels in the forest? A for-