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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."'"
We have seen its effect on the solar system but I don't think we have any really evidence for what exactly Dark Matter is?
Is it matter? is it particles?
We have theories on what Dark Matter is, but those theories could be completely wrong.
So dark matter, as we know it, might not exist, all we know is that something is causing the effects that we see.
Troll is not a replacement for I disagree.
We have so much evidence about the existence of the dark matter that's not even funny: https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence
All indirect evidence. Personally the idea of an invisible, intangible, ethereal magical material that helps peoples sums add up is dubious at best. There are plenty of other good theories out there that do not include this populistic hypothesis.
such as http://www.springerlink.com/content/g332701735121773/
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).
NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
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.
I understand that saying "we don't know what dark matter is" is unsatisfying, but some particles don't interact much with other particles. Neutrinos are a great example, since they only take part in the weak force and gravity (so not the electromagnetic or strong forces). Is it so hard to believe that some matter interacts solely through the gravitational force? That would mean no electromagnetic effects and almost no interactions with other forms of matter. Such matter would only be noticeable at gravity-dominated, cosmological scales.
Who knows? Maybe there's a whole segment of matter humans are unfamiliar with which interacts very little with the matter we know about but interacts with itself in complicated ways. Maybe there are dark matter solar systems populated by dark matter people who are just as confused as we are about the weird gravitational anomalies caused by our otherwise invisible existence. Communicating through gravity would certainly be an interesting challenge! I don't really believe this, but my point is basically the same as Hamlet's: "There are more things in heaven and earth than are dreamt of in your philosophy"--that is, it's arrogant to expect humans to be in a position to observe all the parts of the universe. Perhaps some things are just hidden.
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.
In other words, gravitational lensing of light waves - which is 100% direct evidence of matter - shows a region where there is matter that is clearly non-baryonic (i.e. does not interact with the electromagnetic field, a.k.a. "dark"). This is not subject to dispute. The question of what, exactly, is dark matter - is indeed still a subject of scientific research. There are, however, a number of super-symmetric theories which posit super-partners for well known particles, the most stable of which turn out to have the exact characteristics we're noting observationally. It is important to note that these theories were not tailored to account for the dark matter, but seem to fit the observational evidence quite well so far. As with all science however, theories are subject to falsification at any times as soon as new evidence comes on the scene.
So, it could be that the laws of physics are slightly off, and Dark Matter is just an illusion we "see" because of the errors in physics.
Or Dark Matter could be actual matter, and is just ... dark.