News Scan Briefs; April 2002; Scientific American Magazine; by Philip Yam, Alison McCook, JR Minkel; 2 Page(s)

In No Uncertain Terms: The Bohr family has finally released the mysterious letters that Niels Bohr wrote but never sent to Werner Heisenberg. They shed some light on the two physicists' mysterious meeting in 1941, which became the basis for Michael Frayn's play Copenhagen. In the letters, released in February, Bohr indicates that Heisenberg was not in fact stalling the Nazi atomic bomb program, as Heisenberg later claimed. "You spoke in a manner that could only give me the firm impression that, under your leadership, everything was being done in Germany to develop atomic weapons," Bohr wrote. The documents are not likely to be the last word, as some historians think Bohr could have misinterpreted Heisenberg's statements.-Philip Yam

Gene Fiends?: As genetically modified crops in North America grow, so does the debate over their use. A January report commissioned by the British conservation group English Nature showed that in Canada neighboring canola crops modified to be resistant to different kinds of herbicides have cross-pollinated and produced seeds that contain multiple resistances. If left behind after a harvest, the seeds could grow amid new crops or in field margins; English Nature argues that the offspring could become noxious weeds uncontrollable by existing chemicals. Keith Downey, research scientist emeritus at Canada's Saskatoon Research Center, disagrees. Canadian researchers expected resistance genes to accumulate, he says, and because there are more herbicides than resistance genes, the plants are just as easy to control as singly modified varieties. "The presence of the additional gene doesn't change it one little bit," Downey contends.