Scientist: "Dark Matter" Is A Load Of Crap

He claims that the various anomalies thought caused by "dark matter" are explainable by an adjustment to the formulas describing the effects of gravity:

A modified theory of gravity that incorporates quantum effects can explain a trio of puzzling astronomical observations – including the wayward motion of the Pioneer spacecraft in our solar system, new studies claim.

The work appears to rule out the need to invoke dark matter or another alternative gravity theory called MOND (Modified Newtonian Dynamics). But other experts caution it has yet to pass the most crucial test – how to account for the afterglow of the big bang.

Astronomers realised in the 1970s that the gravity of visible matter alone was not enough to prevent the fast-moving stars and gas in spiral galaxies from flying out into space. They attributed the extra pull to a mysterious substance called dark matter, which is now thought to outweigh normal matter in the universe by 6 to 1.

But researchers still do not know what dark matter actually is, and some have come up with new theories of gravity to explain the galaxy observations. MOND, for example, holds that there are two forms of gravity.

Above a certain acceleration, called a0, objects move according to the conventional form of gravity, whose effects weaken as two bodies move further apart in proportion to the square of distance. But below a0, objects are controlled by another type of gravity that fades more slowly, decreasing linearly with distance.

But critics point out that MOND cannot explain the observed masses of clusters of galaxies without invoking dark matter, in the form of almost massless, known particles called neutrinos.

Okay, got that? Well there's another non-dark-matter theory, too.

Now, Joel Brownstein and John Moffat, researchers at the Perimeter Institute for Theoretical Physics and the University of Waterloo in Ontario, Canada, say another modified gravity theory can account for both galaxies and galaxy clusters.

The theory, called scalar-tensor-vector gravity (STVG), adds quantum effects to Einstein's theory of general relativity. As in other branches of physics, the theory says that quantum fluctuations can affect the force felt between interacting objects.

In this case, a hypothetical particle called a graviton – which mediates gravity – appears in large numbers out of the vacuum of space in regions crowded with massive objects such as stars. "It's as if gravity is stronger" near the centres of galaxies, Brownstein told New Scientist. "Then, at a certain distance, the stars become sparse, and the gravitons don't contribute that much." So at larger distances, gravity returns to the behaviour described by Newton.

Okay, physics geeks: In Ringworld, Larry Niven postulated that the maximum allowable speed (usually the same as the speed of light) was not constant, but was low when near a "singularity" (a massive body like a star) and very high when away from such a mass. Thus permitting FTL travel when you were far away from a star.

Which I always thought was silly.

Does this second theory have anything to do with that?

posted by Ace at 06:53 PM

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