Survey Finds No Hint of Dark Matter Near Solar System

Eponymous Hero writes "Does dark matter exist or doesn't it? It seems these results don't shed as much light as we'd hoped. 'Moni Bidin says he's not sure whether dark matter exists or not. But he says that his team's survey (PDF) is the most comprehensive of its type ever done, and the puzzling results must be reckoned with. "We don't have a good comprehension of what is going on," he says.' This has the smell of a Neutrinogate scandal, but at least we've been warned about the shoulder shrugging. 'As an example, Newberg notes that the researchers assumed that the group of stars they examined were smoothly distributed above and below the plane of the Milky Way. But if the distribution turns out to be lumpier, as is the case for stars in the outer parts of the galaxy, then the resulting calculations of dark matter density could be incorrect. Flynn agrees that there are a number of ways that the method employed by Moni Bidin and his co-authors "could get it wrong."'"

Re:I'm not surprised

[thegreatemu]

At first, maybe. Dark matter was proposed to explain the high velocity of stellar orbits, and dark energy to explain the redshift of distant stars. However, cosmologists later used dark matter and dark energy theory to predict the angular spectrum of the cosmic microwave background and the baryon acoustic oscillation peak in galaxy distributions.

Predictive power ftw!

Re:Of course it exists

[buchner.johannes]

Dark matter is the name of the problem, not the solution.

It may not be particles, but the universe is very well described by the cold dark matter particle model (plus dark energy).

Re:Of course it exists

[hazem]

that helps peoples sums add up is dubious at best.

I think it's a bit more than just coming up with stuff willy nilly.

We have these theories that work great for a lot of observations. They break down a bit for some observations, but can be "fixed" by adding dark matter. This either means the theories are wrong somehow, or there is something out there that's not been accurately observed, or maybe both. The key is to come up with experiments that can falsify the proposition that there is dark matter and that it's the cause of the aberrations.

A nice analogy is the discovery of Neptune. The theories predicted the planets would move in such a way. However they didn't quite do that. But by assuming another planet (which had not been observed), they could get their sums to add up. The testable part of it was when they said, "look here, and you should find a planet that's causing these deviations", and behold, they did.

The thing is, the current theories, even if they're wrong with dark matter, they're "close" to whatever the real situation is because they work so well in most cases. That means the "correct' theory won't be too extremely different, or must at least reduce to the current theories for the special cases we have observed.

If there are competing but "good" theories out there, the key is to find out what differentiates them in their predictions, then to devise experiments to observe what happens in those cases. If you can't devise and carry out such experiments, then it's all mere speculation.

Re:Of course it exists

[Charliemopps]

Sorry, you're off base. Dark matter, whatever it is, has mass but does not interact with other matter or energy. This doesn't just mean that it doesn't give off or reflect light and radiation. It also means that it's transparent to light and radiation. Per observation, there are huge swaths of "dark matter" between us and other stars/galaxies. Yet we can see these radiation emitting bodies undistorted, so whatever is there generating the gravitational effect must be totally transparent to every form of radiation we can measure. "dark matter" was a poor choice in a name. It's not dark, and it very likely is not even matter.