Compared to dark energy or fluctuations in the cosmic microwave background, dark matter is not quite so daunting to explain. It is indirectly detected through its gravitational pull on visible matter – stars and galaxies. There's a lot of it and we don't know what it's made of but scientists...
Category: dark matter
Compared to dark energy or fluctuations in the cosmic microwave background, dark matter is not quite so daunting to explain. It is indirectly detected through its gravitational pull on visible matter – stars and galaxies. There's a lot of it and we don't know what it's made of but scientists have their theories. And so there was some fanfare made over the results of an experiment called AMS meant to detect positrons that would theoretically be emitted if antimatter takes a particular form, called WIMPs (weakly interacting massive particles), and these said WIMPs collide.
The experiment is also interesting because it was conceived by particle physicist Sam Ting, and because it’s flying on the International Space Station. The results were not definitive, but there was enough to work with.
I was disappointed to see little if any explanation for why the experiment flew on ISS and not some unmanned craft. Or why it was so atronomically...
Ron Cowen has a nice piece at Nature on the "long-standing but little-publicized software problems" of NASA's Fermi Gamma-ray Space Telescope. Since its launch in 2008, Cowen...
Ron Cowen has a nice piece at Nature on the "long-standing but little-publicized software problems" of NASA's Fermi Gamma-ray Space Telescope. Since its launch in 2008, Cowen reports, the world's leading gamma-ray telescope has had only a clouded view of the highest-energy gamma rays.
A better view of these gamma rays, with energies greater than 10 billion electron volts, "could yield clues to dark matter and the powerful stellar explosions known as gamma-ray bursts," Cowen writes.
This might have been reported elsewhere before, but Cowen is the only one I could find on Google news who's reporting it this week. And the occasion for the story is that a workaround for the problem was uploaded to the space telescope two weeks ago, and it is now being tested. When this software comes fully online at the end of 2013, it...
The cosmos is the playground of New York Times writer Dennis Overbye, who roams far and wide in his search for news of such things as dark matter, dark energy, strings, and black holes.
In Tuesday's New York Times science section,...
The cosmos is the playground of New York Times writer Dennis Overbye, who roams far and wide in his search for news of such things as dark matter, dark energy, strings, and black holes.
In Tuesday's New York Times science section, he reports that he seems to have found them--in an art gallery in Chelsea, on New York City's far west side.
Beginning with a quote from the Beatles ("Got to be good-looking 'cause he's so hard to see"), Overbye reports that the artist Shea Hembrey has created a collection of paintings and sculptures that he (Hembrey, not Overbye) calls "a collective meditation on the unseen structure of our universe."
"The show features black holes--including one that looks like a bottomless bird's nest...
When it came to tracking...
When it came to tracking interesting physics last week Sir Peter's Particle, ie the Higgs, pretty well blew apart hopes of doing much else. But as the media stampede's dust settles one see through it a nearly coincident smaller instance of herd journalism - and don't take 'herd' as a slight to anybody taking part. For, without such media fixations we'd have even less collective conversation over science news. In Nature an international team (US from U. of Michigan, Kavli-Stanford, Ohio U, and also institutions in Germany and the UK) reported a filament of dark matter between two clusters of galaxies. Actually it's between a duet of clusters on one side, and a third cluster at the other end.
One...
It's interstellar space week for media that follow such things. The American Astronomical Society has gathered in Austin, TX, for its annual meeting. The meeting's press room is streaming its news conferences live on the internet. It's better to be there in person, cruising poster sessions for excloos and schmoozing in all directions, but the live stream ensures more reporting in total.
AAS Press Officer Rick Fienberg reports about 75 people registered for the press room on site, about two thirds of them reporters, editors, broadcasters and so on, with another two dozen or so public information officers. Most of the streaming press...
This just in -...
This just in - science is not an entirely dispassionate and cordial collective enterprise of converting ignorance into solid theory and data. It is done by mortal people with ambitions, envies, alliances, grudges, embraces, and changes of heart. Data count. But so do the combative, defensive lizard reflexes raging up from our brain stems.
The small gaggle of reporters who follow the hunt right underfoot for the dark matter that holds galaxies and their clusters together - by scientists setting their germanium detectors inside mountains or deep underground and thus shielded from most cosmic rays - will know that some sort of joust is underway. Some competing groups say they see a...
In mid-April operators of the Xenon100 experiment in a lab inside...
In mid-April operators of the Xenon100 experiment in a lab inside a mountain in Italy reported new limits on the nature of wimps or whatever dark matter particles may be - meaning they've seen nothing in their first 100 days of operation. Too bad, but the field got a little perkier this week.
At the American Physical Society meeting in Anaheim, workers at another underground lab, in Minnesota, said their CoGeNT experiment can do a tad bit better. It has an asymmetry in results. Something seems to be slapping their device's detector - its heart a one-pound hunk of germanium crystal - a little more often in summer than in winter. That's consistent with something a different Italy-based test with sodium-iodide crystals has said it...
After more than three months operation a detector called XENON100, carrying 62...
After more than three months operation a detector called XENON100, carrying 62 kg or about 135 pounds of liquid xenon and a bunch of photoelectric cells to see if the xenon flashes in a subterranean lab off a traffic tunnel through Italy's Gran Sasso mountain, has gotten zilch. That is, nothing looks like what a dark matter particle might leave behind if scientists are correct about there being such things as dark matter particles heavy enough to be called WIMPs. Hi def version of illus here.
It still could be there, but have a mass or energy beyond what this detector's sensitivity. As often happens, this null...
Catching up still further on holiday...
Catching up still further on holiday omissions, Scientific American in the last days of 2010 ran, from Bruce Dorminey, a thoughtful and well-constructed story on dark matter particle skeptics. These are cosmologists and other physicists who agree something peculiar out there is distorting gravity - as gauged by the rotation patterns of galaxies, lensing of light as it traverses vast distances, and other such incontroverted observations.
But they don't think the case is good that swarms of particles - little motes that we'd be able to detect if just we had the right way...
About a week ago at ...
About a week ago at Symmetry Magazine, the in-house pub of FermiLab and Stanford's SLAC laboratory, blogger Rhianna Wisniewski reported a preprint paper making the on line rounds via the arXiv early-publishing site. Other media have since perked up.
The news is cool, and utterly arcane. , triggering other media to perk up. The spectrum of the signal fits what some expect from collisions between dark matter and the ordinary kind. This, aside from indirect evidence such as excess mass in galaxies and the gravitational...
A little bump is riffling astrophysics. Just a tiny one that, one...
A little bump is riffling astrophysics. Just a tiny one that, one suspects, means little. But so interesting. Last week in New Scientist Eugenie Samuel Reich reported a University of Durham team's startling conclusion that dark matter, even dark energy, may not after all that's been said about them be needed to explain astronomical observations of the universe and the gravitational fields that fill it.
A hint to how far this may go is in her fourth graf, which identifies one of the lead authors of this thesis (in a paper to appear in Monthly Notices of the R.A.S.:...
©2010 Knight Science Journalism at MIT. All Rights Reserved.