Web edition: April 11, 2006
Print edition: April 15, 2006; Vol.169 #15 (p. 239)
Regarding "Blasts from the Past: Astronomers begin to go the distance with gamma-ray bursts" (SN: 2/11/06, p. 88), why is it that visible light is shifted to lower frequencies but gamma rays aren't? Shouldn't they have become X rays after all that distance?
All wavelengths are redshifted. That means that high-energy gamma rays beyond a detector's energy range would get shifted into the detectable range by cosmic expansion, while slower-energy gamma rays would get shifted to below the detector's range.R. Cowen
There are several problems with the popular-press interpretation of the study described in "Low-Fat Diet Falls Short: It's not enough to stop cancers, heart disease" (SN: 2/11/06, p. 85). The study saw a reduction to only 29 percent of calories from fat, which is still far above the 20 percent-or-less advocated by dietary and cardiovascular experts. Also, no one in the field of heart disease prevention would advocate solely reducing fat intake. For instance, salt intake needs to be reduced, exercise needs to be added, stress should be avoided, and diets should include more fruits and vegetables and less red meat and simple carbohydrates.
Glenn M. Gungel
Science takes another big hit from the results of the new low-fat study. What is troubling is the number of people whose behavior was affected by an earlier study's faulty conclusions. Nonscientists are becoming increasingly cynical about scientific research. The fields of nutrition, medicine, and environmental studies appear to be particularly vulnerable to this problem. We scientists need to spend a little more time and some intelligent design in policing ourselves to ensure that our credibility is preserved.
St. Louis, Mo.