In reading “Toxins All around Us,” by Patricia Hunt [Forum], and the text pertaining to how the environment influences our genes in “10 Unsolved Mysteries,” by Philip Ball, I wonder about the following: If toxins in the environment are affecting our bodies in a negative way, as Hunt in particular asserts, and if some genes that were heretofore inactive are now being reactivated in response to chemicals in the environment, as Ball refers to, might these newly activated genes allow us to evolve to cope with all these toxic exposures? Perhaps that’s what they are there for. Maybe our bodies of the future will be able to be healthy within this toxic mix.
John Maas Rua Ernesto do Oliveira
São Paulo, Brazil

Regarding the discussion of biofuels in “10 Unsolved Mysteries,” you seem just as unwilling as other publications to discuss the economic law of diminishing returns. I don’t know exactly when this law became taboo, but technology-related reporting is especially notorious in this regard. Given the time and money spent researching biofuels, hybrid engines, hydrogen fuel-cell technology, and the like, it seems reasonable to suppose that, at some point, all this effort could be better spent investing in something like effective mass transit.
David R. Witzling
via e-mail

In “The Dark Side of the Milky Way,” Leo Blitz states that what dark matter consists of “remains as elusive as ever,” that the most conservative analysis is that it “consists of an exotic particle not yet detected in particle accelerators” and that it “reveals itself solely by its gravitational influence.”

A person familiar with the history of physics cannot help but think of the “ether”: that equally mysterious “substance” scientists of the 19th century supposed must exist, even though it could not be detected, to explain how light, then thought of exclusively as a wave, could propagate through space. The understanding of the dual nature of light made the ether’s existence unnecessary. We should thus not be surprised if a future, more complete theory of the nature of gravity, space and time will also render dark matter nothing more than a historic construct.
Harvey Smith
Carrollton, Tex.

Blitz replies: It remains possible that modifications to Einstein’s general theory of relativity could be responsible for the various phenomena that dark matter is invoked to explain. Nevertheless, despite the example of the ether, the history of astronomy is replete with dark objects that were later identified by other means. These include Neptune and the companion of Sirius, both of which, like dark matter, were first identified by their gravitational effects alone.

While reading “The Scent of Your Thoughts,” by Deborah Blum, I was somewhat startled to read a comment on University of Chicago researcher Martha McClintock’s “friendly face and flyaway hair” and later a description of her clothes (“She wears a tweedy jacket over a bright, patterned shirt”). What has her appearance got to do with her considerable achievements as a scientist? I suspect that if she had been male, such comments would not have been written, and they are irrelevant, irrespective of gender. If I had read this in my local newspaper, I would have just rolled my eyes and sighed. Based on the usual standard of writing in Scientific American, such comments have no place in your journal.
Sam Vincent
Auckland, New Zealand

In “Afghanistan’s Buried Riches,” Sarah Simpson discusses the availability of rare-earth elements, which are needed for high-tech manufacturing but are in short supply. She does not, however, note that these minerals are present in nuclear power plant “waste.”

In roughly 50 years of operation the U.S. has accumulated about 60,000 metric tons of used nuclear fuel. Within that so-called waste stream, one can find significant amounts of cerium, samarium, gadolinium and europium, all rare-earth elements listed in the article.

One would also find actinides, heavy radioactive elements such as plutonium and uranium that can act as future fuel. That is, the waste still contains around 95 percent of the energy that could have been extracted had the fuel put into the reactors been used properly, as detailed in your December 2005 issue in “Smarter Use of Nuclear Waste,” by William H. Hannum, Gerald E. Marsh and George S. Stanford.
Van Snyder
La Crescenta, Calif.

One of David Pogue’s points in “Big Progress on the Little Things” [TechnoFiles] is that the standardization of power cables is a highly desirable, and long overdue, trend in the gadget industry. He rightly points out that USB has become the industry standard (although he fails to emphasize that microUSB, not miniUSB, is becoming the de facto standard in the U.S.) for devices from cell phones to e-readers to MP3 players. But what he should have added is “except for Apple.”

Apple continues to refuse to wholly conform to USB conventions but rather still mainly uses a proprietary 30-pin dock connector. And instead of condemning the company, he applauds it for being “standardized” within its own ecosystem, for forcing customers who buy products outside Apple to have multiple power cords and for adding to the stockpiles of proprietary Apple cabling that grow the size of our landfills.
Adam Royce
San Diego