By Steven Hyman

Web edition: November 7, 2008

Two crops, only one pops In “Let’s get vertical” (SN: 10/11/08, p. 16), writer Rachel Ehrenberg reports that “increased demand for a single crop, such as corn, is felt from movie theaters to hog farms.” It is important to note, however, that the corn fed to moviegoers and the corn fed to farm animals aren’t the same thing. In fact, they are two distinct and different varieties. Popcorn is Zea mays averta, a type of flint corn. The corn used as animal feed, called dent corn or field corn, is Zea mays indentata. Try to pop field corn, and you’ll just get hard, tough, hot corn. Jeffry D. Mueller, Eldersburg, Md. The reader is correct that popping corn and field corn are two different varieties. But the markets for the crops are intertwined. Demand for field corn—which is also used in corn syrups, in products such as paint and, increasingly, in ethanol—has led to price increases, prompting some farmers to switch from popping to field corn. This cuts supply of popping corn and ups its price. —Rachel Ehrenberg Shifting paradigms I wanted to congratulate you on the cogent article by Tom Siegfried on the nature of spacetime (“It’s likely that times are changing,” SN: 9/13/08, p. 26). Since the contributions of Einstein and a few of his contemporaries, physicists have been stuck in the mud as far as new paradigms in physics are concerned. The problem to my mind has been the understanding of time and the entrenched belief that the constants of the universe are the same throughout the universe and throughout time. If physicists wish to make real progress, they need to open their minds to two fundamental ideas: First, our universe is a bottom-up reality, not top-down, with forces and structure due to emergent properties that evolved from the hierarchical interactions “built” at the most fundamental level from quanta. Second, all constants are relative in space and time. The constants and properties we observe and can so accurately measure and (sometimes) predict are the result of the central tendency of an astronomical number of quanta. In short, the universe is statistical. We are forced to observe and measure nature as a part of it. Time is an illusion based on the changing interaction of nature itself. Finally, although Darwin may not have realized it himself, he did not only discover and elucidate the way biology changes, but also the way the entire universe evolves as well. The world has yet to completely understand the incredible contribution he has made to science. Ronald McMurtry, Modesto, Calif. Cold down there In the article “Around the ring” (SN: 10/11/08, p. 8), Ron Cowen writes that the Large Hadron Collider is closed down for the winter to conserve fuel costs. Since the major portion of the facility is 100 meters below ground, how much colder is it there in the winter than in the summer? Jesse Stoner, Huber Heights, Ohio “The LHC tunnel is at a constant temperature year round,” says James Gillies, an LHC spokesman. “I don’t have a precise figure, but if you’re down there for a long time, it’s good to take a jacket. The reason we do our maintenance in winter is that energy demand is higher in the winter in this part of the world, so the cost of electricity to us is about 10 times higher in winter than in summer.” —Ron Cowen Drug-focused Every time there is a new discovery relating to human biochemistry, the knee-jerk reaction of Science News has always been: “This may lead to the development of a new drug,” as in “Dopamine’s role linked to location” (SN: 8/2/08, p. 8). However, it has become clear in the past 30 years that new synthetic drugs often cause more harm than good. Why not: “This discovery may lead to a new dietary approach, or a new combination of nutrients and natural phytochemicals to treat such-and-such disease.” The degree to which it would be unthinkable for Science News to print some version of this statement is exactly the degree to which pharmaceutical thinking (and politics) have taken over the minds of scientists and science writers. Irv Givot, Sisters, Ore. Clashing continents Sid Perkins’ article about the effect on CO2 levels when India and Asia collided was very interesting (“Continental clash cooled climate,” SN: 10/11/08, p. 12). Mentally following the progress of India from Gondwana to Asia got me thinking that, of course, this continental wandering hasn’t stopped. Where do geoscientists predict this ongoing migration is going? Skip Simonds, Studio City, Calif. If present-day plate motions continue, in the next 50 million years the Atlantic Ocean will widen, Africa will collide with Europe and parts of California will slide northward to Alaska. About 250 million years from now, most major landmasses will join together to form a supercontinent—just as they have several times in the past billion years, geological evidence suggests. —Sid Perkins Calming imagery Regarding the article “Pain relief you can believe in” (SN: 10/11/08, p. 9): Surely there must be equivalent calming imagery that would have a similar effect on pain perception and brain activity in those unaffected by the religious imagery. I doubt it’s the religious symbols per se that caused the effect. More likely, the Virgin Mary image did not have the same mental or emotional effect on those not predisposed to view a religious icon as an emotionally and spiritually uplifting image. Wayne Harris-Wyrick, Oklahoma City, Okla. Mars-Earth collision “Impact may have scarred Mars” (SN: 7/19/08, p. 10) interested me. It stated that “something big smacked into Mars and stripped half the crust off the planet”. I also understand the current theory of the formation of the Moon is that a Mars-sized object sideswiped the Earth. I know nothing about celestial mechanics, but is there any way that the Earth and Mars could have collided? The impact on Mars might have been smaller if it had formed further away from the Sun and thus had cooled and solidified more by the time of the impact. Dick Smith, Kingsland, Texas Planetary scientists don’t believe Mars and Earth could have collided, given their current orbits and where they would have been located in the early solar system. – Ron Cowen Calories over contaminants I would like to make an observation about “Plastics chemical takes another hit” (SN: 10/11/08, p. 14). The article reported on research in which a link was made between the presence of a chemical called bisphenol A in certain types of beverage cans and the incidence of heart disease and cancer. However, correlation is not causation. As an early stage diabetic I know that it is what goes in the can that you eat or drink that is of utmost importance. I think it is the calories and the kind of calories that make up the product that really matter. Mike Moody, Newnan, Georgia The reader is correct that correlation is not causation. Diseases such as cancer and diabetes are complex and scientists are still trying to ascertain how factors such as heredity, chemical exposure and diet—to name a few—may conspire to bring about disease. – Rachel Ehrenberg Waves pass through Regarding “Solid evidence about Earth’s core” (SN: 9/13/08, p. 14): If Earth has a solid inner core but a liquid outer core, any direction you look at it the shear waves have to go through some outer core before they get to the solid inner core. So how do they get through the molten outer core? Tom Turner, Newport, R.I. When the shear waves traveling down through the mantle reach the liquid outer core, some of their energy is converted into pressure waves (which can travel through liquid, unlike shear waves). When those pressure waves reach the solid inner core, some of their energy is converted into shear waves. Once these vibrations reach the other side of the solid inner core, some of their energy is converted into pressure waves that rise through the outer core. Finally, when these waves reach the mantle, some of their energy is converted to shear waves that then spread and can be detected by seismometers at Earth’s surface. Each of these conversions -- four, count em! -- is relatively inefficient, which leaves very little energy in the particular vibrations that scientists needed to identify to prove their theory. – Sid Perkins