MOG SYNTHESIZERS:

Cosmic collision explained without dark matter (Physics World, 11/06/07)

To see how mass is distributed in the Bullet Cluster, scientists examine how it behaves as a “gravitational lens” by bending the path of passing light. In 2006, astrophysicists noted that X-ray light emitted from very distant galaxies travelling through the Bullet Cluster to Earth was bent more by the small galaxies at the sides rather than the hot gas dominating the centre, which represents most of the normal matter. This implied that there is an extra mass component that is not associated with normal matter, leading many physicists to hail it as strong evidence for dark matter. Assuming conventional theories of gravity are true, dark matter is predicted to comprise about 95% of all gravitating mass in the universe.

Moffat and Brownstein, however, argue MOG can provide a more natural explanation by removing the need to invoke mysterious dark matter. Essentially MOG adds extra terms to Einstein’s theory of gravitation — general relativity — that allow the gravitational constant G to vary across space and time. The researchers modelled the hot gas distribution using their MOG theory, and found the gravitational force would be stronger as you move away from the centre of the Bullet Cluster, explaining the stronger lensing seen at the edges.

“Whenever dark matter is said to dominate a system, in MOG, the extra gravity exerts a strong and measurable influence based only on the observable [normal] matter,” explained Brownstein. The researchers have used MOG before to explain the dynamics of hundreds of galaxies and clusters.

These guys don't do science, just science fairs. You choose whose model you like better.

Posted by Orrin Judd at November 6, 2007 7:02 AM