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 might offer that the researchers might better have called that fat connector a bridge, not a filament. (Hold it! Just read Amina Khan's LA Times story, below. It explains we're seeing this thing in foreshortened perspective - it really would be long and skinny if we saw it broadside.)
Evidence for it includes a good deal of mathematical digestion of the data, including visible evidence. The latter, already well in hand before this recent study, included a soft X-ray glow and a scattering of galaxies at the same distance as the larger galactic cluster bulbs. They inferred the dark matter from the distortion of background galaxies as their light got bent by gravity when going past and through the bridge. The distortion implies a gravity field ten times stronger, or so, than what the visible gas and galaxies could provide. And dark matter is the likeliest suspect as its main source. At least that's how this old tracker reads the paper. Most important, the analysis's conclusion fits well with theoretical models of how visible galactic clusters would mainly lie at the intersections or odes in a cosmos-spanning skein of less-dense filaments and bridges of dark matter. Now the greater warp and woof of matter's main material seems to have been glimpsed.
- LA Times - Amina Khan : Dark matter filament found, scientists say / Astrophysicists say they have discovered one strand of the long-elusive dark matter filaments, though to connect galaxies and help shape the universe ; Ha, perspective, as noted above. Speaking of that her first source quoted is not an author of the paper, but a local expert on the topic.
- Christian Science Monitor - Pete Spotts: Cosmic scaffolding uncovered? Scientists find thread of dark matter.
- Ars Technica: Matthew Francis: Dark matter is the thread connecting galaxy clusters ;
- Popsci - Rebecca Boyle: In a Cosmology Breakthrough, Astronomers Measure a Filament of Dark Matter ; Good example why most old time science journalists have taught themselves to quash the syllables "break" and "through" when they hook up in the mind's meanderings. One must ration it, preserve its meaning. This discovery is solid and significant, sure. It is hardly a breakthrough. It confirms a theory, doesn't propel it forward, does not settle a great argument among alternatives, and opens no windows of insight.
- The Register (UK) Rik Myslewski : Revealed at Last: Universe's intergalactic dark matter skeleton / Boffins' first glimpse of the structural framework of our universe ; What?! No pictures? An absensce more than compensated by the cheeky lede: "Higgs, Schmiggs ... What that infinitesimal speck was sucking up all the journalistic oxygen..." and so on. Exactly well put. Except for the part about this being a 'momentous scientific discovery.' It's diverting, but mainly a relief to see backing for a grand theoretical expectation but surely not the turning point that the word 'momentous' implies.
- Science News - Devin Powell: Dark matter filament illuminated ;
Grist for the Mill: University of Michigan Press Release ; It calls the threads and cables of dark matter "highways of sorts." Not highways of no sort at all, metaphoric or otherwise, one thinks. Why plant the wrong word in the collective mind of the aggregator sites? Does one call the ranks of marching soldiers "highways of sorts"? No. Dark matter's ropy lineaments are more like strands of a spider's web, snaring the regular matter that comes by, agglomerates, and lights up.
*UPDATE: In comments, the release's author explains. It makes a lot more sense now. I still don't think the metaphor quite works but regret the overdone tenor of my remarks immediately preceding.
- Charlie Petit