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As the son of the man whose name is attached to "Murphy's Law," I want to thank you for accurately and respectfully identifying the origin of this "law" in your recent article ["The Science of Murphy's Law," by Robert A. J. Matthews, April]. My father was an avid reader of Scientific American, and I can assure you that were he still alive, he would have written to you himself, thanking you for a more serious discussion of Murphy's Law than the descriptions on the posters and calendars that treat it so lightly. Yet as interesting as the article is, I suggest that the author may have missed the point of Murphy's Law. Matthews describes the law in terms of the probability of failure. I would suggest, however, that Murphy's Law actually refers to the CERTAINTY of failure. It is a call for determining the likely causes of failure in advance and acting to prevent a problem before it occurs. In the example of flipping toast, my father would not have stood by and watched the slice fall onto its buttered side. Instead he would have figured out a way to prevent the fall or at least ensure that the toast would fall butter-side up. Murphy and his fellow engineers spent years testing new designs of devices related to aircraft pilot safety or crash survival when there was no room for failure (for example, they worked on supersonic jets and the Apollo landing craft). They were not content to rely on probabilities for their successes. Because they knew that things left to chance would definitely fail, they went to painstaking efforts to ensure success. EDWARD A. MURPHY III After receiving more than 362 intact issues of Scientific American, I received the April issue--with the article on Murphy's Law--that was not only assembled incorrectly by the printer but also damaged by the U.S. Post Office during delivery. My teenage daughter is taking this magazine into her science class to talk about Murphy's Law. The condition of this issue is an excellent example for her presentation. BRAD WHITNEY
Like Richard E. Rice, Raymond E. Gullison and John W. Reid, authors of "Can Sustainable Management Save Tropical Forests?" [April], we are dedicated to conserving biodiversity in the tropical rain forest, and we are doing so both commercially and sustainably. We have been working for four years on 40,000 acres of Paraguayan forest that has been certified as well managed. In addition, we are shipping lesser known species to market, and we are making money. Our experience suggests that the authors' conclusions may not apply across the tropics. Their example--cutting only one species in a species-rich, high-volume forest--is both atypical and one of the least efficient ways to generate either short- or long-term profits. It has been our experience that sustainable forestry need not be any more expensive than massive, indiscriminate extraction or single-species elimination.
JEFFREY ATKIN
Pardon some observations from a simple patent litigator regarding the article by Leonard Susskind, "Black Holes and the Information Paradox" [April]. (Albert Einstein was a patent examiner, after all.) Consider that the quantity of information that can be transmitted is usually viewed as a function of carrier wave frequency--a 28.8 modem typically carries more information than a 14.4. If strings slow their vibration frequencies as they approach a black hole, their ability to carry information should also decrease. At a carrier frequency of zero, no information can be carried. How can strings carry or radiate information once they're at the horizon of a black hole?
ROBERT KUNSTADT Susskind replies: Kunstadt makes an interesting point. Someone stationed far from a black hole that is absorbing a flow of information carried by an electromagnetic wave sees the frequency of the wave diminish as it approaches the horizon. So, as Kunstadt indicates, the flow of bits must also diminish. But information is not lost at the horizon. There is no limit on how much information can be carried at low frequencies, only on the rate of flow of that information.
I was disappointed to read "A New Take on Telomeres" [News and Analysis, "In Brief," May], which refers to studies purportedly demonstrating that the link between cell aging and telomere loss is wrong. Telomere length can be in a dynamic flux in immortal cells, but this finding does not negate the fact that aging is linked to telomere loss in mortal dividing cells. Our original observations have been confirmed and extended in numerous labs over the past seven years. Suggesting that new insight into additional regulators of telomere length in immortal cells disproves the telomere hypothesis of cell aging is a bit like concluding that since your bank account fluctuates up and down even when you have an income, it won't shrink when you spend without one.
CAL HARLEY
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