MOND Matters
I am glad to see Mordehai Milgrom's alternative to the dark-matter theory ["Gravity's Gadfly," August]. I will be happy to have dark matter consigned to the same place as ether and phlogiston, other substances postulated to exist without some defining properties of matter. Both had some odd properties and turned out to be undetectable. Of course, dark matter has its own set of odd properties (transparent but with enough mass to affect the rotation of galaxies) and as of yet is also undetected. Milgrom's equation may not be a valid solution, as changing Newton's formula in only certain circumstances seems a bit like hand-waving to me. On the other hand, once it is further developed, I think it has more potential than dark matter.
Daniel Rubin
Wynnewood, Pennsylvania
Good-bye, Gasoline
"Life After Oil" [August] by Robb Mandelbaum was rather balanced discussing the pros and cons in the present race to ethanol. However, far too much money in the form of federal grants and subsidies is being invested in an ethanol culture, considering that it's a low-efficiency fuel. If the ethanol is made from corn, huge amounts of fossil fuel are consumed in producing the man-made fertilizer required to grow it. A gallon of diesel fuel contains 139,000 British thermal units per gallon, gasoline has 124,000, and biodiesel 120,000, while ethanol contains only 76,000. A diesel engine extracts more energy from its fuel and can travel much farther on a tank than can an ethanol-fueled vehicle. And the diesel-fuel distribution system is already in place nationwide—not so with ethanol.
Robert Abramson
Stonington, Connecticut
Mandelbaum fails to acknowledge a potential drawback of ethanol. He implies that the use of ethanol will increase as the costs decline when the technology to convert cellulose, hemicellulose, etc., from stalks, husks, and other biomass becomes more efficient—that is, when we can convert more of the plant to ethanol. However, this biomass is not "free." Its breakdown is needed to enrich the soil. Without it, we are even more dependent on synthetic fertilizers, which require a lot of energy to produce and are proving to be far less effective at protecting soil quality and nutrition than fertilizers derived from organic sources.
Garry W. Auld
Department of Food Science and Human Nutrition
Colorado State University
Fort Collins, Colorado
Familiarity Breeds Content
In his essay "Sing a Song of Evolution" [August] on the possible evolution of language from song, Jaron Lanier speculates that our music has lost some of its variety and blames it on the tools we use to make the music. It's more reasonable to conclude that music in the United States is now much more rigid for the same reason it is for birds in the wild. In a world that seems to be getting bigger, we're limiting the numbers of our "calls" so that similar types of people can find each other. We're free to travel anywhere for jobs or a change of scenery, so we feel a need to seek the stability of people who enjoy the same songs and culture, or "plumage."
Walter Acuña
Burbank, California
Our Bad
Due to an editing error, August's Map (Data) states that the "extra girth around [Earth's] middle partly explains why things weigh more there than at the poles." The sentence should have read, "This extra girth around the middle partly explains why things weigh more at the poles." The photo caption on page 53 of the August issue states that the creatures in Will Wright's computer game Spore can be rendered in three dimensions for a fee. Electronic Arts, the game's publisher, has not confirmed that it will make 3-D versions available to the public.
