Since we relaunched Technology Review in mid-1998, we've taken as our mission telling you about the most important emerging technologies and their potential impact on our society, economy, culture and individual lives. Most of the time, fulfilling that mission means talking about the remarkable transformative power of new technologies. We live at a time when three simultaneous technology revolutions are under way-in information technology, biotechnology and, just over the horizon, nanotechnology. What's more, those three revolutions will ultimately merge into a single force capable of changing almost everything about what it means to be human. As a result, writing and reporting for Technology Review is, most of the time, a pretty upbeat job.

Not always, though. One reason is that if our mission is to delineate the impact of emerging technologies, implicit in that mission is a responsibility to spell out the limits of those technologies-what they can't do now and won't be able to do in the future as far as we can see into it. We're intrigued by the power of new technologies, but we're not true believers in them. We aim to be just as hardheaded as we can. And the responsibility to be skeptical is never more important than when the stakes are high, when what's at issue isn't just economic or cultural change but the safety of our friends and family and neighbors. In the special report that forms the heart of this issue of Technology Review, "Technology vs. Terror," we've tried to give you a clear picture of just what it is that technology can do to help make us safer-along with what it can't do.