March 18, 20255 min readReaders Respond to the December 2024 IssueLetters to the editors for the December 2024 issue of Scientific AmericanBy Aaron Shattuck Scientific American, December 2024WATERY SANCTUARIESIn The Afterlives of Oil Rigs, Asher Radziner describes how oil rigs are habitats for marine species and explores the question of whether they should be allowed to remain after they stop producing oil.For years I was an avid diver and dove on several oil rigs. I must admit that these were some of my most memorable dives. These rigs provide a sanctuary for an amazing variety of life, essentially an oasis in an ocean desert. Little, if any, life would exist there if not for these structures. Taking them down would destroy a well established ecosystem, not to mention that doing so would cost a lot of money.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.RANDY LANDRY VIA E-MAIL A COLORFUL PASTI thoroughly enjoyed The Map Color Conundrum [Math], Jack Murtaghs overview of the historical controversy over the four-color theorem, which states that no more than four colors are needed to fill in a given map so that no designated areas have the same color. Murtagh notes that Kenneth Appel and Wolfgang Haken finished a computer-aided proof of the theorem in 1976. No disrespect to Appel and Haken, but I dont regard their work as the final word on the matter. In his 1940 book A Mathematicians Apology, the great English pure mathematician G. H. Hardy stated, Beauty is the first test: there is no permanent place in the world for ugly mathematics. I await a more elegant proof.Of course, Martin Gardner published a famous counterexample of the four-color theorem in Scientific American back in April 1975.EAMONN WATERS RANGIORA, NEW ZEALANDMURTAGH REPLIES: Waters is in good company with many mathematicians who await a more elegant proof of the four-color theorem. Regarding Gardners publication: In 1975, only a year before Appel and Haken proved the theorem, Gardner played an April Fools prank in his long-standing Scientific American column Mathematical Games. He published a map with 110 regions and claimed that it could not be colored with only four colors, thus disproving what was then the four-color conjecture. Of course, the map did indeed have a four-coloring scheme (like all maps, we now know); it was just difficult to find. Gardner enlisted the help of mathematician William McGregor for the hoax and acknowledged it in his July 1975 column.HEALTH ANXIETYAs a psychologist, I appreciated Joanne Silberners attention to a condition that is so often minimized and used to dismiss peoples concerns in Hypochondrias Serious Toll. But I think it is important to recognize the role of safety behaviors and negative reinforcement, concepts that werent directly discussed in the article. They are central to a cognitive-behavioral understanding of the development and maintenance of illness anxiety disorder and somatic symptom disorderthe two separate syndromes that are referred to as hypochondria, as Silberner notesas well as related disorders. And addressing these concepts is central to effective treatment intervention.DANIEL KLEINER REHOBOTH BEACH, DEL.Having spent four decades as an internist, I have seen many people with hypochondria and have struggled to provide an appropriate treatment plan for these complicated patients. The article notes a book in which the author describes how he underwent multiple hospital tests for cardiac symptoms that all had normal results and how many of these symptoms were actually the side effects of a drug he had switched to on his own insistence. There is a twist to this kind of story: an aggressive response from a physician can unintentionally produce a positive feedback loop in which the patient (perhaps subconsciously) thinks, If this is nothing to worry about, why is my doctor ordering all these tests?IAN J. WILSON COLUMBUS, OHIOWHALES AND CARBONI was fascinated by Buried at Sea, Jaime B. Palters article about proposed engineering to promote the sequestration of carbon dioxide in oceans. Recently I read about how a whale can do the work of those engineering marvels. Whales fertilize the ocean surface, which in turn promotes phytoplankton growth. In addition to providing more food for larger animals, the increased amount of phytoplankton absorbs atmospheric CO2. And when these organisms die and sink to the ocean floor, they take carbon with them. It seems that protecting and nurturing whale populations to bring them back to their historical numbers may be the best bet for our own future.EVELYN WIEBE-ANDERSON ARCATA, CALIF.PALTER REPLIES: The idea of restoring whale populations is attractive, mostly because it aims to rewild the ocean and bring it back to its state before human activity degraded the ecosystem. There is no direct evidence, however, that it can make a meaningful dent as a method of prompting the ocean to store more carbon. Scientists have tried to estimate how much additional carbon sequestration whale restoration can provide (both directly, such as by the entrapment of carbon in whale carcasses, and indirectly, such as by the stimulation of phytoplankton growth).The top-line numbers for direct pathways dont indicate climate-relevant scales, although there are deep uncertainties, especially regarding the indirect pathways, that would require future research for us to understand and better quantify. Luckily, making our oceans more sustainable and restoring ecosystems can have cultural and economic value that goes well beyond dealing with carbon.GALAXY BRANDINGI have to agree with Phil Plaits assessment that Milkomeda is an awful name for the potential future merger of the Milky Way and Andromeda galaxies in The Milky Ways Fate [Universe]. He suggests Andromeway would be even worse, and I have to agree again, but he is on the right track. I think a snappier name for the merged galaxy, one that would sound better and flow off the tongue with greater ease, would be the Andy Way.NELSON G. THOMAS VIA E-MAILCLARIFICATIONUntangling the Vagus Nerve, by Jena Pincott [January 2025], described a 2017 study of people with treatment-resistant depression that found vagus nerve stimulation halved symptoms for 67.6 percent of them. This result refers to a decrease of 50 percent or more.ERRATUMTessellation Revelation, by Elise Cutts, incorrectly said that the faces of a polyhedrons dual correspond to the polyhedrons edges and vice versa. Rather the faces of each shape correspond to the vertices of the other.The Astronaut Club, by Clara Moskowitz and Zane Wolf [Graphic Science; February], incorrectly represented data regarding astronauts Christina Koch, Joe Engle, Michael R. Clifford, Susan J. Helms and Timothy Nash. Corrected illustrations can be viewed here.