In “From Dark Matter to Light: New models of galaxy formation show the gastro in physics” (SN: 3/22/08, p. 186), Ron Cowen says that gas is where the action is since dark matter predominantly responds to only gravity. Because dark matter responds to gravity, wouldn’t it, like gas, be pulled into the star-making process and become part of the resulting star? Why is our sun not predominantly dark matter?
Eugene (Gene) Cater
On the largest scales, the amount of dark matter is much greater than the amount of baryons—ordinary atoms. But on the scale of individual planets or stars, there is more ordinary matter. That’s because baryons can radiate away their energy (ridding them of heat that would fight gravity) and therefore clump more tightly under the influence of gravity than can dark matter (which can’t radiate), says theorist Piero Madau of the University of California, Santa Cruz.—Ron Cowen
“Rotten Remedy: Hydrogen sulfide joins the list of the body’s friendly, if foul, gases” (SN: 3/8/08, p. 152) shows the formula for sodium hydrosulfide as NaH2S. Would it not be more accurate to present it as NaHS?
G. David Grubbs
The reader is correct.
Respect the past
I feel that Rachel Ehrenberg was entirely too glib in “Digging that Maya blue” (SN: 3/1/08, p. 134). The description of an ancient Mayan religious ritual as “plucking the hearts from humans and tossing the bodies into the sacred cenote” is disrespectful. I am sure that Science News would never describe any contemporary religious rituals in this manner. Here is hoping that the editors and writers adopt a more dispassionate eye.
Gerard J. Cerchio
San Francisco, Calif.