O Come, All Ye Scientists

Scientists from Manhattan to Pasadena, Moscow to Johannesburg, responded to The Scientist's question, "What gift do you most want this holiday season, and why?" Answers included the practical (sliceable gel blocks), the whimsical (a Star Trek tricorder), and meteorological (another El Niño). But what they all had in common was the desire for that most intangible and elusive of gifts: hastened progress in the researchers' respective fields.

For upcoming missions to Mars and Europa to search for life, Chris McKay, professor of astronomy and planetary scientist with NASA Ames Research Center in Moffett Field, Calif., says he wants a tricorder. "As every Star Trek viewer knows, a tricorder is a device [that] can detect life forms, even from orbit."

But even better than a tricorder, and a more reasonable wish, would be a grasp of the principles on which a tricorder works, or an understanding of the observable properties that ...