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Hubble Telescope Maps Dark Matter in 3D
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.'"
According to one researcher, the findings provide "beautiful confirmation" of standard theories to explain how structures in the Universe evolved over billions of years.'
... thereby proving god exists.
Push Button, Receive Bacon
I wonder what a 3d model of dark matter around a black hole would look like? Does it share the same properties as regular matter near a black hole?
To those /.ers that know more of physics than I do, is Dark Matter supposed to be some actual particle, or is it a kind of natural gravitational topography? Everything I read ( quick google search/old copy of "Elegant Universe") about it seems to be rather vague and mysterious.
We are all just people.
Think of it this way. On slashdot you have a lot of posts. Some of them are good. But they can't all be good all the time. So it follows that there has to be bad posts. Lot's of them.
That's dark matter.
I think that should be a modifier. -1, Dark Matter
Don't be mad that you didn't think of it...
clifgriffin > blog
"beautiful confirmation" of standard theories?????
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 and even worse dark energy.
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.
-Ariel
"We understand statistically what those galaxies are supposed to look like,"
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.
Yes, there is, but we do not have a clue yet of what it is made of.
Astronomers have ways to measure the mass of objects, like galaxies, and cluster of galaxies, using a theory of the gravitation. For galaxies, the classical newtonian theory is enough: they just measure how fast the stars and the gas orbit around the galaxy, and derive directly their mass from kepler laws. For clusters of galaxies, or large structure, they use the bending of light by mass from general relativity. These measure are getting reasonably accurate. When they compare these masses to the mass they actually can see (stars, gas, etc..), they find that they can only account for 1/6 of the total mass they measure, well above all the uncertainties of the measurments. Therefore, there must be some matter (that is, something with a mass), that we cannot see (that does not interact via electromagnetism). This is the dark matter.
For more info, there is a [wikipedia] entry.
Maybe because Dark matter doesn't damn you to hell for wanting to have sex? Or because it is not based on campfire tales of desert nomads from thousands of years ago, but rather mathematical equations, observations, you know, scientific stuff.
Note to self: No more arguing with the faithful.
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 (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.
Any information may be true or incorrect depending on your perception of said information
- The current accepted theory of gravitation, general relativity, works extremely well: it's predictive power has so far never be successfully challenged. Many have tried, noone has succeeded.
- MOND had some success in explaining various observational puzzles, but has also some problems with others, as the wikipedia entry you link indicates.
- MOND is an ad-hoc theory, just like dark matter is an ad-hoc solution
- It is very hard to change your theoretical framework, much easier to add some stuff to the universe.
This explains to me why, right now, the current accepted paradigm is dark matter. While it is not satisfying, it is enough to explain both the rotation curves of disk galaxies, and the formation and evolution of the large scale structure of the Universe. I don't think many astronomers are satisfied with this current situation, and some are trying to resolve the issue, either explaining dark matter or getting rid of it. The others find with dark matter a framework where they can go on in exploring other scientific questions, like the evolution of galaxies, where you need to explain how their (normal) matter was assembled together, but also how this matter (gas) is made into stars, etc...Next time you get an infection, please do us all a favor and take the ID challenge: http://www.doonesbury.com/strip/dailydose/index.ht ml?uc_full_date=20060702
The plural of 'anecdote' is not 'data'. --Dan Kaminsky
No. Neutrinos aren't massive enough to be (most of the) dark matter. See here for a brief but more detailed discussion.
The real story of how we ended up with dark matter is not widely understood or accepted.
Some time ago, a man named Hannes Alfven, who is today considered the father of plasma physics, founded the field of magnetohydrodynamics, which astrophysicists have been using to model plasma in the universe for several decades now. This field treats plasma as a fluid and assumes that currents cannot flow through the plasma because it treats plasma as an ideal conductor with no resistance. This is actually not *anything* like the way that plasma operates in the real world, and since plasma represents 99%+ of all observable matter within the universe, this massively incorrect assumption yields absurd results in astrophysics today. Plasma is in fact electrically conductive and its electrical properties interact with its mechanical motions, and vice-versa. If you've ever seen a novelty plasma globe, then you intuitively know that plasma is not like a fluid. You can tell by looking closely at a plasma globe that the plasma creates filaments and these filaments pair up and twist around one another. These twisting currents are called Birkeland Currents. As the current flow increases through them, they pinch together with increasing force and this pinching action can actually condense matter into a ball. This is a big deal because there is no good reason to believe that molecules will gravitationally collapse from a diffuse collection of matter in space; in fact, gases obviously expand in a vacuum. Contrary to the more popular beliefs propagated in astrophysics and the media today, the z-pinch effect is likely actually how planets and stars form. Astrophysicists don't understand this because of their earlier assumptions regarding plasma being a fluid with no currents. But we can see strong evidence of Birkeland Currents and Z-Pinches happening through our telescopes.
The thing is, astrophysicists will see what they want to see through the telescope. All observations today are interpreted through mainstream concepts like stellar evolution and Big Bang theory. When an anomaly pops up, it can be a very simple matter to propose a "patch" for the theory to keep it going. Astrophysicists will invoke collisions, black holes, gravitational lensing or malformed electrical theory in order to explain away anomalies. But you will notice that anomalies are discovered nearly every week these days (especially with stellar evolution), and this is a problem because things like collisions should not actually be happening as often as they are being invoked to dismiss the anomalies.
When Hannes Alfven received his nobel prize for plasma physics in the 70's, he recused himself from the field that he created (MHD) and warned astrophysicists to abandon it, and that the path they were taking would eventually dead-end. But they completely ignored him and continue to do so. So, now we have mysterious forces tugging on matter throughout the universe that we can't see. This is what we call dark matter. Dark energy is supposed to be matter that can gravitationally repel. Electrical forces can accomplish both of these feats without any mysterious matter. All you have to do is drop the earlier incorrect assumptions about plasma and accept that extremely diffuse plasma flows can and do exist. You will notice over time that the dark matter studies will reveal some details that correspond with the properties of electricity over plasma. For this particular article, it was noticed that the structure of the dark matter was in places filamentary. Filamentary structures are far easier to generate with electricity than with gravity. It was also mentioned that dark matter can exist in the absence of physical matter. This is to be expected with plasma because plasma can consist of just electrons and ions, or it can also be coexisting with or collecting dust.
Some brave scientists and electrical engineers called Electric Universe Theorists are working on understanding the universe in terms of real plasma physics -- which makes p
"A man cannot begin to learn that which he thinks he already knows." --Epictetus, 1st Century A.D.
# The current accepted theory of gravitation, general relativity, works extremely well: it's predictive power has so far never be successfully challenged. Many have tried, noone has succeeded.
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.
_
\\/ are accustomed' - First Lensman
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. 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.
now I can hang my map of dark matter up right next to my picture of albino polar bears walking the tundra in a blizzard.
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Yes, there is, but we do not have a clue yet of what it is made of.
Well, most of science has yet to agree what it is, but Randy Mills has a pretty solid theory backed by observations.
Mainstream says the 10% of the universe that is observable is 90% hyrogen, 9% helium, and 1% everything else. Mills says that the 90% unobservable universe is a lower-state hydrogen atom that he calls a "hydrino". The Mills theory explains the answers to some very old scientific questions, such as 'what happens to a photon upon absorption' and explains why the Sun's corona is so hot (>1,000,000 K) in spite of the fact that Sun's surface is so cool (6,000 K), and correctly predicted the accelerating expansion of the universe before it was observed (there was no big bang, just a sinusoidal expansion/contration where we are currently on the accelerating region of the curve).
The foundation of Mills theory is that an electron is spherical shell, not a point. From this posit pretty much everything can be explained with 4 dimensions, Newtwon, Maxwell, and relativity - with no need for string theory, spooky interaction, uncertainty, or quantum mechanics.