Haunting the Web Since 1999
By way of Dangerous Meta, did Dark Matter kill the dinosaurs? Extremely speculative here, but food for thought. “The European Space Agency’s Gaia mission, which launched last year, will map the gravitational field of the Galaxy and could rule out or confirm the presence of this darker disk.”
There are older things than Orcs in the deep places of the world: Symmetry Magazine checks in with the Cryogenic Dark Matter Search experiment happening a mile beneath Minnesota. As I’ve mentioned before, I came close to spending a summer in high school standing around a similar underground science project, searching for neutrinos. “The year 2013 should be an interesting one in the search for dark matter.”
This came out while I was in Seattle and I’ve been meaning to catch up: By measuring the cosmic background radiation still extant from the Big Bang, the ESA’s Planck satellite gives us our most detailed map of the universe yet.
“[T]he new satellite data underscored the existence of puzzling anomalies that may yet lead theorists back to the drawing board. The universe appears to be slightly lumpier, with bigger and more hot and cold spots in the northern half of the sky as seen from Earth than toward the south, for example. And there is a large, unexplained cool spot in the northern hemisphere.”
I find these maps particularly fascinating because, as I said when NASA’s WMAP returned its data in 2003 (and here in 2002), I spent the summer of 1992 poring over the original COBE DMR version of this map for my high school senior thesis, in order to determine whether the radiation exhibited a fractal distribution. (And, honestly, how early 90’s is that?)
“‘A.M.S. has confirmed with exquisite precision and to high energy one of the most exciting mysteries in astrophysics and particle physics,’ said Justin Vandenbroucke, of the University of Wisconsin and Stanford’s SLAC National Accelerator Laboratory.” In related news, NASA’s recently-installed Alpha Magnetic Spectrometer on the ISS is helping physicists and cosmologists get to the bottom of the dark matter mystery.
The A.M.S. has “confirmed previous reports that local interstellar space is crackling with an unexplained abundance of high energy particles, especially positrons, the antimatter version of the familiar electrons that constitute electricity and chemistry…’Over the coming months, A.M.S. will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin.’“
“If DAMA’s signal were due to dark matter, Xenon 100 would have seen dozens of events — unless the properties of dark matter are very different than expected, says Lang. ‘If DAMA really does see dark matter, it has to be something very, very exotic, something much different from what we expect, so it’s getting a bit unlikely.‘” A new study casts doubt on apparent discoveries of dark matter particles by the DAMA experiment. Back to MOND, then?
“The second law states that a force is proportional to an object’s mass and its acceleration. But since the 1980s, some physicists have eyed the law with suspicion, arguing that subtle changes to it at extremely small accelerations could explain the observed motion of stars in galaxies.” Also on the subject of spinning, a new experiment finds a way to test Modified Newtonian Dynamics (MOND) on Earth, which, if successful, could revise Newton’s heretofore ironclad 2nd law…and explain away the longstanding dark matter problem. (By way of my new favorite Twitter feed, @newscientist.)
Using the thankfully soon-to-be-refurbished Hubble, astronomers find more evidence of “dark energy” in the early universe working along the lines of Einstein’s famous fudge factor, the cosmological constant, to combat a gravitational crunch. “‘Dark energy makes us nervous,’ said Sean Carroll, a theoretical physicist at the California Institute of Technology who was not involved in the supernova study. ‘It fits the data, but it’s not what we really expected.’“