Thread: Scientists Say Dark Matter Doesn't Exist

http://www.space.com/scienceastronom...og-theory.html

Last August, an astronomer at the University of Arizona at Tucson and his colleagues reported that a collision between two huge clusters of galaxies 3 billion light-years away, known as the Bullet Cluster, had caused clouds of dark matter to separate from normal matter. Many scientists said the observations were proof of dark matter's existence and a serious blow for alternative explanations aiming to do away with dark matter with modified theories of gravity.

Two Canadian astronomers think there is a good reason dark matter, a mysterious substance thought to make up the bulk of matter in the universe, has never been directly detected: It doesn't exist.

"MOG gravity is stronger if you go out from the center of the galaxy than it is in Newtonian gravity," Moffat explained. "The stronger gravity mimics what dark matter does. With dark matter, you take Einstein and Newtonian gravity and you shovel in more dark matter. If there's more matter, you get more gravity. Whereas for me, I say dark matter doesn't exist. It's the gravity that's changed."

What do you think?

I'd like to know:

1. Does this 'MOG' theory account for the 90% discrepancy we see between observed matter and assumed gravitational forces (ie that the universe seems to be almost perfectly poised between eternal expansion and a Big Crunch)?

2. If gravity is variable with distance from large masses, does this make it fundamentally different from the other three forces or are they too subject to such effects? If so, another thread here (I think started by zinjanthropus) would be very relevant - the gravitational effects upon light, the uncertainty as to light's 'actual' velocity in a vacuum, and so on - meaning that the universe needn't be expanding at all?!!

You can find more info here I think:

http://www.arxiv.org/abs/astro-ph/0608675