It also gives us an opportunity to reflect on how scientific inquiry directs new technology.

One area worth noting is global warming and the role of nuclearpower plants in reducing emissions of greenhouse gases. Global warming itself is still a subject of great debate. Proponents of apocalyptic warming scenarios point to computer projections as one reason for their concern. Many of these projections show steadily rising worldwide temperatures and implicate greenhouse gases as the culprit.

Skeptics, on the other hand, don't buy the argument and point to the same computer projections as the reason. They note, among other things, that computer models have an unimpressive track record for accuracy when it comes to predicting either short or long-term global temperatures.

Computer projections also enter into the debate about new nuclear-reactor designs, a subject MACHINE DESIGN has covered in the past. Experts say pebble-bed nuclear-power plants are orders of magnitude safer than those now in place. These experts also base their arguments on computer projections.

But the antinuke movement disagrees, maintaining that computer projections of reactor safety can't be believed. They may have a point if history is a guide. Sadly, for example, NASA calculations of Space Shuttle safety at the beginning of the program proved to be far off the mark.

There is an irony here. Many of the same people willing to accept computer projections of global warming refuse to accept computer projections of reactor safety. This is an interesting position to take. It is reasonable to think that the creators of both sets of calculations would use recognized statistical methods for determining probable error. So a more logical position would be to buy both sets of projections, or neither.

Solar power is another area MACHINE DESIGN has covered from time to time in which there continues to be ambiguity. No question that solar is the great hope of the alternative-energy crowd for replacing hydrocarbon-burning generators. But consider that commercially available solar cells can capture about 30 W/m2. This sounds promising until it's compared to typical usage rates.

New York City, for example, consumes about 55 W/m2 of city surface area. Powering a city like the Big Apple with solar cells would entail covering an area twice that of the metropolis itself. Though there are more efficient solar cells on the horizon, even doubling cell efficiency would only halve the space requirement. So don't count on solar to replace conventional power plants anytime soon.

Besides, there is still a good argument to be made that we already use sunlight wisely, even without lining the earth with solar cells: It is great for growing plants, trees, and wilderness.

— Leland Teschler, Editor