From the title - "This result doesn't rule out alternate gravity theories like MOND".
Actually, this directly rules out MOND. That's a big part of the point of the experiment.The idea is that the mass in these clusters doesn't come from the obvious sources of visible matter (the gas), as it would in a MOND or normal gravity scenario, but rather from the invisible (i.e., dark) matter.
I think you're referring to cosmological redshift here - the redshift that makes objects farther away seem redder. You're correct that GR doesn't predict cosmological redshift a priori; cosmological redshift is caused by the expansion of the universe, and GR allows for an expanding universe, a contracting universe, or even a static universe. But GR does demand that gravitational redshift exist. This redshift is caused by the curvature of spacetime by matter which lies at the heart of GR itself, so graivtational redshift is tightly connected to GR, and its observation an important piece of evidence for the theory.
It seems to me that Lucas could run into lots of trouble with sequels conflicting with the enormous, convoluted, and in places, self-contradictory universe of the Star Wars Books.
Of course, the solution I propose is to use the Trhawn series as the scripts for the sequels. Does anythone think that this could actually happen?
Slashdot Mirror
From the title - "This result doesn't rule out alternate gravity theories like MOND". Actually, this directly rules out MOND. That's a big part of the point of the experiment.The idea is that the mass in these clusters doesn't come from the obvious sources of visible matter (the gas), as it would in a MOND or normal gravity scenario, but rather from the invisible (i.e., dark) matter.
I think you're referring to cosmological redshift here - the redshift that makes objects farther away seem redder. You're correct that GR doesn't predict cosmological redshift a priori; cosmological redshift is caused by the expansion of the universe, and GR allows for an expanding universe, a contracting universe, or even a static universe. But GR does demand that gravitational redshift exist. This redshift is caused by the curvature of spacetime by matter which lies at the heart of GR itself, so graivtational redshift is tightly connected to GR, and its observation an important piece of evidence for the theory.
It seems to me that Lucas could run into lots of trouble with sequels conflicting with the enormous, convoluted, and in places, self-contradictory universe of the Star Wars Books. Of course, the solution I propose is to use the Trhawn series as the scripts for the sequels. Does anythone think that this could actually happen?