Hubble Telescope Maps Dark Matter in 3D 174
dido writes "The BBC reports that the Hubble Space Telescope has been used to make a map of the dark matter distribution of the universe, providing the best evidence of the role dark matter plays in the structure and evolution of the universe. From the article: 'According to one researcher, the findings provide "beautiful confirmation" of standard theories to explain how structures in the Universe evolved over billions of years.'"
dark matter does not exist (Score:3, Insightful)
What standard theories? Dark matter does not exist, as least not as far as anyone (except astronomers with good imaginations) knows. There is a very nice (and complete!) standard model of physics, and dark matter holds no place.
I should qualify, I'm talking about theroes of non-baryonic dark matter [wikipedia.org] and even worse dark energy [wikipedia.org].
Regular matter, that is simply dark - i.e. cold, and not emiting light, does not bother me. But making up particles no one has ever seen just because you don't understand what you are seing is fitting facts to the data.
Scientists often discuss new theories, etc, and in that context dark matter has it's place, but to claim it exists - as this story does - without being able to actually measure anything is quite silly and premature. If you don't understand something, say so, don't invent plausable explanations that have nothing supporting them except your lack of knowledge.
RTFA (Score:2, Insightful)
So this map is based on what they assume the universe should look like. Then they use how its different to find where the dark matter might be. Doesnt sound 100% certain by any means, but its a nice picture.
Re:dark matter does not exist (Score:5, Insightful)
Re:RTFA (Score:2, Insightful)
There is no assumption on the Universe is supposed to look like in this map. The only assumption is that the General Relativity of gravitation is correct. So far, it has not been disproved.
Re:Does Dark Matter exist? (Score:3, Insightful)
This is what I don't get about dark matter, and this is just how I see it, and no one has ever given me a decent explanation. Why is it that scientists think that dark matter exists simply because the observed galaxies don't conform to Newton's Laws? Wouldn't a simpler solution be to take a step back and consider that, maybe, Newton's Laws are flawed? I am not trying to disprove dark matter, I certainly am no cosmologist, but it just seems odd that so much attention is given to dark matter, and very little is given to competing theories, such as MOND [wikipedia.org](Modified Newtonian Dynamics), that to me, at least, make more sense.
My basic point is, from a layman's perspective, dark matter just sounds like something physicists pulled out of thin air to explain something they don't understand. Your observations don't make sense? Well, throw in some dark matter and we're good!
Can someone explain to me why dark matter is the prevalent theory? Or perhaps why something like MOND is always ignored? As I said, I don't know what is right, but it just seems like a hack-job to me.
Re:Does Dark Matter exist? (Score:3, Insightful)
Re:dark matter does not exist (Score:2, Insightful)
I smell a Thomas Kuhn moment in the making. Or at least, a phlogiston moment.
Explaining the universe is hard. But saying stuff like "it's real", even implying that it is
Re:Enlighten me (Score:3, Insightful)
I fail to see how it is a "poor excuse" for anything, it's mearly a description of something we don't fully undersatnd but can indirectly observe and therfore label. Maybe our elegant theories will need to change to account for future observation but right now our notion of what we label as "dark matter" explains the observed anomolies better than any other concept, including the proposed modifications to gravitational theory.
For a historical perspective you just need to go back a hundered years to a time when scientists were having a similar debate about the existance and structure of atoms. Sure the model of atoms looking like "a pudding with razor blades stuck in it" fell by the wayside when it failed to explain all the observations. That is how science progresses, it's an evolution of ideas and analogies, not a static statement of "the truth".
Re:Does Dark Matter exist? (Score:3, Insightful)
You mean, apart from the fact that you need to create 90+ percent more matter in the universe than what is visible to prevent galaxies from flying apart?
i.e. without dark matter (and dark energy), gravity doesn't predict much.
Dark matter == epicycles? (Score:3, Insightful)
Some skepticism is certainly in order. Since we currently have no way of independently confirming the existence of dark matter, we also have no way of distinguishing between two possible cases: one case is that dark matter corresponds to some real, physical material; the other is that the theory of gravity we're using is flawed. The fact that a better theory of gravity hasn't been produced doesn't mean that the current one is correct.
There are pretty strong parallels between dark matter and the infamous epicycles [wikipedia.org]. The case for epicycles was about as strong as that for dark matter: epicycles were a construction required to make the theory work, but there was no way to independently verify their existence, and they turned out to be essentially fictitious (assuming one doesn't take the position that they could be turned into a valid way of describing the solar system's orbital motion taking the Earth as center.)
The real problem is that there are no checks and balances here: by adjusting the mass distribution of dark matter, we can get whatever result we want, and there's nothing to either prove or disprove the proposed distribution. It's the ultimate hack, since it can be adjusted to suit every individual galaxy we observe.
In the absence of independent evidence of dark matter, it would be more elegant if laws of gravity were discovered which explained the observations well without dark matter.
That's a pretty weak position. It certainly doesn't do anything to counter the accusation that objects are being invented just to make the theory work.
Re:Does Dark Matter exist? (Score:2, Insightful)