letters to the editor to find their way back to their beehive”), and interestingly In praise of the Slinky ignores substantial evidence indicating adverse health effects In the process of preparing a lecture on my adventures of mobile phone use in students (e.g., headache, concentra- with oscillations and waves, I considered a wide range of wave tion problems, fatigue, depression, poor sleep quality, and machines dating back to the middle of the 19th century, and 2,3 insomnia). Moreover, while the author has paid attention came to the conclusion that if you can only have one wave to the effects of radio frequency radiation on orientation in machine, you ought to have a Slinky. bees, other health effects of cell phone use such as sedentary For my 10th birthday in 1947 I was given a Slinky. At behaviors on cardiorespiratory fitness are entirely forgotten. the time it was best known for its ability to descend a flight In this light, limiting the health effects of mobile phones to of stairs, one at a time. It was invented by a naval engineer cancer can mislead teachers (and their students). named Richard James in 1943, and when it was introduced at Moreover, Plotz seems to be interested in the findings of Christmas time in 1945, the inventory sold out in 90 minutes. the INTERPHONE study (“There are two big studies using Only when I began to teach physics at Kenyon did I realize this design. The first was the INTERPHONE study con- that it was the ultimate wave machine. Early in my career I ducted in 13 different countries and investigating more than acquired one about seven inches long. When laid on a smooth 5000 glioma cases”) and claims, “In this study the researchers floor and stretched out to a length of 10 or 15 feet, and with conclude that there is no significant effect. They do not see a reliable student anchoring the far end, it is easy to send a a link between glioma and the usage of mobile phones. Parts transverse pulse down the length of the widely spaced coils. It of another study confirm this result.” It should be noted that can also be used to send a longitudinal pulse down the device, recently Momoli et al. have performed a reanalysis of the although this is best seen if the students are standing at either Canadian data from the 13-country INTERPHONE case- of its ends. control study, and when they applied a probabilistic multiple- With a little practice you can also set up a standing trans- bias model to address possible biases simultaneously, the verse wave one half wavelength long, one wavelength long, etc. odds ratio (OR) for glioma comparing highest quartile of use Standing longitudinal waves are a bit harder but are possible. (> 558 cumulative lifetime hours of use) to non-regular users However, standing waves can be set up only in bounded sys- was 2.0 (95% confidence interval: 1.2, 3.4). When adjusted for tems; the wave that is sent down the Slinky interacts with the selection and recall biases, the OR was 2.2 (95% confidence one returning from the far end to set up the stationary pattern. interval: 1.3, 4.1). The tricky thing is looking at boundary conditions. In SMJ Mortazavi my younger days I used to hop up on the lecture bench and, Fox Chase Cancer Center, Philadelphia, PA holding one end of the Slinky above my head, pull up enough coils so that the lower end is just clear of the floor. With the 1. T. Plotz, “Mobile phone radiation and cancer,” Phys. Teach. 55, lower end free, a downward transverse pulse to the right will be 210–213 (April 2017). reflected as an upward transverse pulse also to the right. How- 2. L. Vernon, K. L. Modecki, and B. L. Barber, “Mobile phones ever, if a student holds the bottom of the Slinky to the floor, it in the bedroom: Trajectories of sleep habits and subsequent will be seen by the class that a downward pulse to the right is adolescent psychosocial development,” Child Develop. (May 29, reflected as an upward pulse to the left. Once this idea is estab- 2017). PubMed PMID: 28556891. lished, you can then display the familiar textbook diagrams in 3. H. Tamura, T. Nishida, A. Tsuji, and H. Sakakibara, “Associa- which a pulse approaching the end of a cord disappears into tion between excessive use of mobile phone and insomnia and depression among Japanese adolescents,” Int. J. Environ. virtual space, while a similar pulse, either upright or inverted, Res. Public Health 14 (7) (June 29, 2017). PubMed PMID: propagates out of virtual space and into real space. 28661428. Pubmed Central PMCID: PMC5551139. Thomas Greenslade Jr. 4. F. Momoli et al., “Probabilistic multiple-bias modelling applied Kenyon College, Gambier, OH to the Canadian data from the INTERPHONE study of mobile phone use and risk of glioma, meningioma, acoustic neuroma, Cell phones, cancer, and other problems and parotid gland tumors,” Am. J. Epidemiol. (May 23, 2017). I have read with interest the article by Thomas Plotz en- 1 PubMed PMID: 28535174. titled “Mobile Phone Radiation and Cancer” wherein he has addressed the possible link between mobile phone use and Correction: “The indeterminate case of cancer. Despite its strengths, this paper has at least one major classical static friction when coupled with shortcoming. This shortcoming comes from the point that readers who are physics teachers (and their students) may tension,” by Kenneth D. Hahn and think the only main problem associated with mobile phone Jacob M. Russell (Feb. 2018), p. 83 use is cancer. Although this paper aims to discuss the cancer In Fig. 1 of this article, the sin and cos were reversed in issue, it discusses the orientation in bees (“Another study with order. The Physics Teacher regrets the error made during pro- bees indicates a connection between microwaves and the ca- duction. (Thanks to Rod Cross for finding the error.) pability to orientate. Bees exposed to radiation were less able The Physics Teacher ◆ Vol. 56, March 2018 131
The Physics Teacher – American Association of Physics Teachers
Published: Mar 1, 2018
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