Letters
By Science News
SN on the newsstand
I’m blind so I’ve been reading your magazine in braille for quite a while. But most of my sighted friends have never heard of you guys. This is a great publication, and I’m glad that more readers will now become familiar with it (“Science News goes public: available on newsstands,” SN: 5/22/10, p. 2).
Rick Lovecchio, Doraville, Ga.
We hope so too. Select bookstores across the country now stock Science News. To find out how to order the braille edition, contact the National Library Service for the Blind and Physically Handicapped at www.loc.gov/nls. — Eva Emerson
RHIC: No catastrophe
Could you give more details on the measurement reported in the March 13 issue (“Physicists cook cosmic soup to 4 trillion degrees,” SN: 3/13/10, p. 8)? You quote one researcher as saying that the photons are “brightest when the matter is hottest” and refer to heated iron going from red to white hot. But I thought that classical physics fell precisely due to the “ultraviolet catastrophe” when the Rayleigh-Jeans formula failed to predict the drop in frequency of blackbody radiation at higher temperatures. This led Planck to his equation and started us on the road to quantum mechanics.
David Sole, Detroit, Mich.
The RHIC researchers did indeed measure thermal radiation, but they used the rules of quantum mechanics to extrapolate the temperature, says Steven Vigdor of Brookhaven National Laboratory in Upton, N.Y. As the reader notes, classical physics overestimated the probability of high-frequency radiation, Vigdor says. “But this does nothing to invalidate the steady march of materials toward higher frequency emission as the temperature is increased. Quantum physics still predicts, and experiment confirms, that the intensity of emitted radiation grows at a given frequency with increasing temperature, and that the mean frequency of the entire spectrum of emitted radiation grows with increasing temperature.” The PHENIX experiment observed very high-energy photons compared with visible light. — Laura Sanders
Neandertal in you
At last, DNA analysis has shown that we carry Neandertal genetics (“Modern people carry around Neandertal DNA, genome reveals,” SN: 6/5/10, p. 5). About time. I had long concluded that Homo sapiens and Homo neanderthalensis must have interbred a lot. There are just too many people who show Neandertal characteristics in their facial bones.