Thursday, November 01, 2007

MOG Trumps Dark Matter?

First we had MOND. Then came the observation from the Bullet cluster that puts MOND into trouble and give further support to Dark Matter. Now along comes MOG (link may be open for free only for a limited time), as reported in today's Science daily news update.

In a paper published online 25 October in the Monthly Notices of the Royal Astronomical Society, Moffat and co-author and Perimeter Institute colleague Joel Brownstein argue that their modified theory of gravity, which they call MOG, can also explain the Bullet cluster discrepancy. Einstein argued that gravity arises because mass warps space and time--he even came up with an equation for how the warping works. Moffat says he added "minimal" additional terms to Einstein's equation that subtly change how gravity behaves on galactic scales. The upshot is that gravity is stronger at these scales than Einstein predicted and that MOG can explain the gravity of the Bullet cluster without dark matter. Brownstein says he and Moffat have applied MOG to the behavior of more than 100 galaxies and more than 100 clusters, and in all cases, it has successfully predicted their motions "without the necessity of adding dark matter."

Of course, many astrophysicists are not convinced, so we will just have to wait and see how this turns out, especially with more and more observations being planned. Even the LHC will come into play at the search for the possible dark matter candidates.


1 comment:

Anonymous said...

The Royal Astronomical Society has released some new images of the Bullet Cluster at jbrownstein/mog/prediction/ -- a spectacular cluster of galaxies merger with a main and subcluster. Is it dark matter? Or is it the visible matter we are certain is there, but according to a modified gravity!