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Dark matter is a big deal. The mysterious stuff makes up about a quarter of the universe, five times more than the ordinary matter of atoms and molecules. But we can’t see it. We can’t touch it. It’s just out there.
But it’s recognized by gravity. Big objects, such as galaxies, feel its gravitational tug. Galaxies such as our own Milky Way are believed to reside inside huge dark matter halos. And massive clusters of galaxies ought to be strung along filaments of dark matter, like pearls on a chain.
But those filaments are awfully hard to detect, being dark and all. Now a team of researchers reports identifying a dark matter filament joining two galaxy clusters. The astronomers used the technique called gravitational lensing to find the giant but invisible structure.
They measured how light from the distant universe gets rerouted slightly by massive objects, like it’s passing through a lens. Sure enough, there was an invisible bridge of massive stuff—dark matter—linking the galaxy clusters. The finding is in the journal Nature. [Jörg P. Dietrich et al., "A filament of dark matter between two clusters of galaxies"]
The filament is an important confirmation that dark matter is real. Now astrophysicists just need to figure out what it is.
—John Matson
[The above text is a transcript of this podcast.]
[Scientific American is part of Nature Publishing Group.]
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3 Comments
Add CommentJust as three dimensional objects would be invisible to two dimensional beings (think "Flatland"), objects that exist in four physical dimensions would be invisible to us 3D's. So if "Dark Matter" was actually matter in 4 dimensions, it would explain why we can't see it, and perhaps help explain why gravity is such a weak force in 3 dimensions.
Reply | Report Abuse | Link to thisI think it's more correct to say that (the improper evaluation of) gravity produces dark matter than to say that dark matter produces gravity.
Reply | Report Abuse | Link to thisPlease see my more complete comments posted to the Nature New article regarding this research
http://www.nature.com/news/dark-matter-s-tendrils-revealed-1.10951
or my more general commentary posted at
http://sciencewithoutfiction.com/uploads/JDwyer.PDF
If you assume that the multiverse exists and that gravity can leak between those universes, then there is another option and explanation why the expansion rate of our universe is growing. After our universe's big bang, what became our galaxies, expanded outward bound by the mutual attraction of this universe's gravity. When the mutual
Reply | Report Abuse | Link to thisattraction of these galaxies was outweighed by the surrounding "other" universes, the expansion would have accelerated. The other universes would be your black matter and the cause of the observed acceleration in our univere's expansion rate.