Astronomers Make Important Dark Matter Discovery

saudadelinux writes "To quote a press release on NASA's site, astronomers using the Chandra X-ray Observatory have discovered 'how dark and normal matter have been forced apart in an extraordinarily energetic collision.' There will be a briefing at noon, August 21 ET, on this discovery, with streaming media provided by NASA, and some details of the research posted on Harvard's Chandra site just beforehand."

Comments

Hmm...

[Stanistani]

I don't know exactly why, but whenever I hear about dark matter, I'm reminded of Zippy The Pinhead.

Re:Hmm...

[decipher_saint]

I don't know exactly why, but whenever I hear about dark matter, I'm reminded of Zippy The Pinhead.

The real question: Is NASA having fun yet?

Nothing to see, move along

[dreamchaser]

How about waiting for the 21st and THEN posting a story. There is literally nothing of substance yet. Oh wait, this is Slashdot. We'll just have it posted again in two days, then on the 21st, then on the 25th, etc.

Re:Nothing to see, move along

[Tackhead]

> There is literally nothing of substance yet.

Not at all. It's got plenty of mass, it's just dark.

Re:Nothing to see, move along

[thePig]

How is parent offtopic?
There is no data, other than what is given in the summary.
If there is no information, why would one want to post the same in /., which is essentially a news discussion/b site.

The only discussion that can happen on this would be pure guessworks, and maybe some funny comments.

Mods, mark parent insightful, not offtopic.

Re:Nothing to see, move along

[Anonymous Coward]

Chances are very good that it's an update to the results published by the same authors in the Astrophysical Journal in 2004, but using newer and much improved data. Pre-prints of the earlier papers are on astro-ph at http://arxiv.org/abs/astro-ph/0309303 and http://arxiv.org/abs/astro-ph/0312273. The papers from a few years ago combined observations of the gas in a merging cluster of galaxies with gravitational lensing data that indicates the distribution of the dark matter. As the two clusters in question merge, the gas from each cluster collides with that from the other, causing it to slow down. The dark matter, on the other hand, doesn't experience this sort of "drag" and just keeps on going, so the dark matter gets "ahead" of the gas.

Re:Nothing to see, move along

[garcia]

"To quote a commenter on Slashdot's site, Slashdot "editors" using the Slash approval queue have discovered 'how people will get annoyed with their Slashbacks that cover previously covered material that were formally known as "Dupes".' There will be a briefing at 12:29 PM CT, on this discovery, with streaming comments provided by Slashcode, and some details of dreamchaser's comment posted on Slashdot's site just beforehand."

Re:Nothing to see, move along

[necro81]

These folks have just been taking a few cues from Steve Jobs and Apple. They announce that they are going to announce something, then let folks speculate wildly about what exactly it will be. Instead of a product launch touting the latest features, it'll be a theory launch touting the latest features. Not too different, really.

The coolest part is when you extend this comparison to include the Reality Distortion Field. The combination of that with dark matter and cosmology could yield some amazing results!

Re:Nothing to see, move along

[WED Fan]

> There is literally nothing of substance yet. Not at all. It's got plenty of mass, it's just dark.

Like Oprah.

Re:Nothing to see, move along

[Pictish Prince]

Yes, it's dark, like fudge.

Re:Nothing to see, move along

[timster]

It's ended up as "Funny", which is rather bizarre.

It's offtopic because the topic is "Astronomers make important dark matter discovery", not "talk about whether upcoming astrophysics press conferences are News for Nerds or not".

There is obviously plenty to discuss, as lots of Slashdotters will want to get up to speed on current dark matter theories in advance of this conference, so that they can understand it.

Re:Nothing to see, move along

[syousef]

Depends on if she's in an expansion or contraction phase....scientist aren't sure if she's an open or closed model but it doesn't stop them from trying to observe her big bang.

Re:Nothing to see, move along

[d_54321]

"Nothing to see, move along": I predict that is what I'll see when I come back to this slashdot article on the 21st.

Question.

[LiquidCoooled]

If you shine a torch at some dark matter what does it become?

Isn't dark matter just all the none illuminated items in the universe?
Rocks and stones and humans and plants and animals and silicon and paper and all these things are what I would consider dark matter, I might be wrong but someone could add some illumination on the subject I would be most grateful.

Re:Question.

[dreamchaser]

A small portion of it is rocks, dust, etc. Prevailing theories hold that much (most) of it is made up of non-baryonic matter which has yet to be observed.

Re:Question.

[Silver Sloth]

Humans, at least alive ones, are not at zero degrees K, and therefore radiate energy, not much, but some. We might be said to be dim matter.

http://en.wikipedia.org/wiki/Dark_matterThis link will tell you more.

Re:Question.

[SupremoMan]

Not at all sir. http://en.wikipedia.org/wiki/Dark_matterThis should enlighten you a bit.

In cosmology, dark matter refers to matter particles, of unknown composition, that do not emit or reflect enough electromagnetic radiation (light) to be detected directly, but whose presence may be inferred from gravitational effects on visible matter such as stars and galaxies.

It's a blanket term used for stuff in the universe we think is there but haven't seen because we can not detect it's presence.

Re:Question.

[Anonymous Coward]

yes, dark matter is the unilluminated matter in the universe. It supposedly consists of both "normal matter" (i.e. protons, neutrons, electrons) which you could "shine a torch at" such as dead stars and planets which dont give off light and "other matter" such as neutrinos and as of yet undiscovered particles. This "other matter" would interact very weakly except through gravity, so if you were to "shine a torch at it" you wouldn't see anything. that's a brief answer, theres more info here: http://en.wikipedia.org/wiki/Dark_matter#Dark_matt er_composition ("normal matter" is baryonic(i.e. contains protons and neutrons), "relativistically" refers to near-light speeds)

Re:Question.

[geekoid]

'Dark' is a code word for 'We don't know.'

Seriously.

Re:Question.

[susano_otter]

It's a blanket term used for stuff in the universe we think is there but haven't seen because we can not detect it's presence.

So... Scientists can't explain how the universe works, without appealing to a mysterious phenomenon they can't observe and whose nature they cannot describe except in terms of its supposed secondary effects?

And this is different from believing in God... how, exactly?

Re:Question.

[Mike Peel]

"And this is different from believing in God... how, exactly?"

We look for explanations of what's going on, not just saying "it's God. Don't go there." Think of dark matter as a placeholder, not the end product. Over time, we should find a reasonable explanation of what's causing the discrepancy, at which point it will just become part of the "normal" physics.

Re:Question.

[farker haiku]

And this is different from believing in God... how, exactly?

Apparently, when you seperate dark matter from normal matter you get an extraordinarily energetic collision, whereas when you seperate a Christian from God you get a rational thinking being.

Re:Question.

[geekoid]

"And this is different from believing in God... how, exactly?"

There is no secondary 'effect' that infers the existance of god.

Be that as it mey, what this means is 'we have observed and effect, now we are looking for the cause.
They seem to be making head way.

Something falling is an effect of gravity. Oberving that effect is what lead to discovering all the cool stuff about gravity.

Re:Question.

[Anonymous Coward]

Because the flow of information is reversed- scientists infer the nature of dark matter from indirect observations of secondary effects. If there wasn't evidence from these secondary effects, then these inferences would be wrong, and scientists would have to come up with a new theory. Sure, there are some scientists who have a lot invested in dark matter, just as there were many prominent scientists who built their careers on the study of luminiferous aether or phlogiston. Time, and science, proved them wrong.

Religionists, OTOH, believe in a Supreme Being a priori, and attribute whatever they cannot otherwise explain to the "mysterious ways" of the divine. The edifice of cosmology would withstand the discovery that there is no dark matter. Would religion be able to withstand the discovery that there is no God?

Re:Question.

[Red Flayer]

And this is different from believing in God... how, exactly?

Believer: There's something we can't explain. God did it.

Scientist: There's something we can't explain. Let's try to figure out what it is.

Believer scientist: There's something we can't explain. Let's try to figure out what God did.

Re:Question.

[Indian]

It is different from God because saying "dark matter" is not the end.
Its only a stop-gap measure until a better theory and or evidence shows up.

The two are very different. "God" is a "no further investigation/arguments" case. Dark matter is not.

Re:Question.

[Sky Cry]

In cosmology, dark matter refers to matter particles, of unknown composition, that do not emit or reflect enough electromagnetic radiation (light) to be detected directly, but whose presence may be inferred from gravitational effects on visible matter such as stars and galaxies.

Re:Question.

[wanerious]

By "not seen", we just mean that it doesn't *glow* like stars, not that it can't be detected at all. In fact, we detect it by the gravitational influence it has on neighboring luminous matter as well as lensing the light of background objects. We can study its large-scale nature and distribution fairly well, just not the composition or small-scale structure yet.

Re:Question.

[Relic of the Future]

Because next week, we'll have a better answer.

And next year, even better.

And next century, better still.

You may now switch argument tactics to "How can you trust science if it keeps changing its answers! Religion has been giving the same answer for thousands of years!"

Re:Question.

[Decameron81]

So... Scientists can't explain how the universe works, without appealing to a mysterious phenomenon they can't observe and whose nature they cannot describe except in terms of its supposed secondary effects?

There is no difference in that both are theories. However there is a big difference in the fact that one is just a theory, while the other is a scientific theory, and the difference between the two, is that one can be tested and has a chance of eventually being proven wrong. I'll let you figure out which one I am talking about.

In any case you should remember that religion is all about faith, which means believing in something you know you can't prove or disprove. Looking at religion using the glasses of science will not lead you anywhere. You should instead understand that science and religion, are not mutually exclusive, and that the tools to be used are different. You can't expect to experiment on the existance of God, just as science isn't about having faith.

Re:Question.

[Hao Wu]

So rather than considering God as a hypothesis (because surely you know the outcome of any related experiment), you have decided that a hypothesis itself is God.

Hypothesis: thou art moron.

Re:Question.

[twifosp]

And this is different from believing in God... how, exactly?

A good logical question. I will attempt to answer it here. While both dark matter and God are both human conjecture, dark matter (and other scientific based conjecture) is different from believing in God in the following ways:

1. Dark matter is based on indirect measurements and evidence which is gathered. God theory is based on information, but no measurement system or indirect evidence, written by men.
2. Allthough no complete explanation for Dark Matter exists, there is a reason Dark Matter is thought to exist; the galaxy gravational constant rotational problem. The only reason God needs to exist is to fufill a human desire. Note: This is my opinion only, and if you do not share it, it is ok. Please don't take it personally.
3. In order to know about the God theory, it MUST be communicated by another human via written word or verbal speech. There is no deriving the God theory on your own without coming up with a drastically different completely unconnected theory.
4. And lastly, but probably most important, a God theory says what IS. A scientific theory says what is NOT. Scientific theory will always admit it is wrong until empirically proven right. A God theory is always right without any direct or supporting evidence.

In conclusion, even a conjecture based scientific theory is based on logical derived thought which does not require blind faith to believe in. In can be derived the same way by any human who performs the same measurements and observations. It can be derived the same way by two humans on opposite sides of the planet without communicating with each other. Religion or a theory of God, as history has taught us, does not share this trait and will be different depending on the humans who wrote it.

Re:Question.

[geekoid]

"Humans, at least alive ones, are not at zero degrees K"

You've never met my ex-wife

Re:Question.

[radtea]

It's a blanket term used for stuff in the universe we think is there but haven't seen because we can not detect it's presence.

It is worth pointing out (as I do every time this topic comes up on /.) that there are multiple dark matter problems on different scales, and there may be multiple kinds of dark matter to explain them (or conversly, multiple defects in our understanding of the laws govering large-scale gravitational dynamics.)

Galactic dark matter, which is used to explain the flat rotation curves of spiral galaxies, could be baryonic--that is, the same stuff we are made out of. There are small enough amounts of it that if it is baryonic it is still consistent with limits on baryon density from primordial nucleosynthesis.

Dark matter on much larger scales cannot be baryonic, and so more exotic particles are required.

Dark matter requires at least three properties to fit the observations:

1) There has to be a lot of it (suggesting a light elementary particle, but not a heavy neutrino because they are too light)

2) It has to have the right dissipation properties. Galaxies, stars and people form because ordinary matter loses kinetic energy to heat in collisions at a fairly high rate. At different scales dark matter needs to lose energy at just the right rate. If it is insufficiently dissipative then galaxy formation does not occur at all, and if it is too disipative then it will condense along with baryonic matter and not give the large scale structure required. It is tricky to get the right mix, especially on all scales.

3) It needs to be hard to detect. If dark matter as an exotic particle exists, it is here now, all around us. Various deep underground experiments have been trying to detect it for over ten years now without any success.

It sounds like this announcement, which is the worst kind of sensationalist science-by-press-release, may be about a detailed study of a colliding cluster, which allows us to pin down the dynamical parameters of the missing matter a bit more precisely. But until we see it in AP.J., who knows?

Re:Question.

[OrangeTide]

Well the existence of the universe could infer the existence of a god or god(s). Where did the big bang come from? Nobody has any idea. For all we know some powerful being poked a hole in the universe with its pinky finger.

I am an atheist and believe in a god-free universe. But if you were a deist, this would be a pretty reasonable explanation. the nice thing about deists is that they are rational and do not believe in miracles, unlike some of the superstitious who believe in god(s).

WRT the article - I can't wait to find out about this Dark Matter stuffs. YAY :)

Re:Question.

[digitalhermit]

Ever read Roger Zelazny's "Lord of Light". In one of the chapters there's a story about battling an enemy that looks like a demon, is strong as a demon, is fast as a demon, etc.. It's not a called a demon, however. One character asks why they make the distinction when it doesn't matter how they go about fighting it (i.e., if it walks like a duck). The other character responds that it is all the difference. To say that it's a demon would be equivalent to "bowing down to the unknown". I.e., dispensing with science and knowledge and bowing to the supernatural. Excellent book.

Re:Question.

[Anonymous Coward]

Religion has had very little problem withstanding the discovery that there is no god.

Re:Question.

[Alsee]

And this is different from believing in God... how, exactly?

Just for starters, you're not going to get some well-organized community deciding it's a good idea to kill you simply for offering a different and better explanation.

-

Re:Question.

[gaspar ilom]

How, pray tell, will this ever come about?

Would religion be able to withstand the discovery that there is no God?

(Religion is here to stay.)

Re:Question.

[Mike Peel]

It sounds interesting; I've added it to my to read list. Not having read it, I obviously can't give a thorough response to your comment - but I'd say that calling something a demon has a lot of metaphysical meaning, i.e. they are inherently evil spirits, summonable, etc., rather than just describing the physical characteristics of something. It's also then a easy step to ghosts and the ilk. In other words, you get a whole lot of preconceptions about aspects of the creature that you're not sure about. Were it just based on the physical attributes, though, then I would imagine the name "demon" would be applied (if we're actually sure what physical attributes a demon has - I couldn't find anything conclusive by a quick google).

Re:Question.

[MS-06FZ]

It's a blanket term used for stuff in the universe we think is there but haven't seen because we can not detect it's presence.

So... Scientists can't explain how the universe works, without appealing to a mysterious phenomenon they can't observe and whose nature they cannot describe except in terms of its supposed secondary effects?

And this is different from believing in God... how, exactly?

I think this is a fair and interesting criticism - but easy enough to answer.

Science is the accumulation of human knowledge. Our best model of the universe we live in. The scientific process governs how new knowledge may be discovered and accepted. But above all, it is an admittedly incomplete understanding of the universe. However, with the knowledge that's been accumulated, we are able to model the behavior of a great many phenomena in reliable ways - from that perspective scientific knowledge has clearly been a success.

The reason "dark matter" came into being (as a theory, I mean) is because we don't yet understand the whole of the universe - its origin, its overall nature, how it interacts with gravitation. But we're trying, you understand. Scientists develop these theories and ponder them, attempt to establish whether they may be true. It's an ongoing process. In this case, it seemed that given the motion of the universe, there ought to be more mass which couldn't be accounted for. Hence this idea of undetectable mass out in the expanses between stars. I'll readily admit that as theories go it's a bit vague, and it fits in (as you suggested) with criticisms of religion: that the idea is established "because" and quite "conveniently" can't be disproven, because the matter is undetectable.

So what's the difference?

First, dark matter is a theory. One of several attempts to explain these phenomena. Propoents of the theory will advocate it but there is no concensus. There are competing theories (equally credible competing theories, I mean) but as a theory Dark Matter has its merits.

Second, the idea of dark matter was introduced as a possible explanation for measured phenomena. And it is a relatively simple explanation: that there is mass out there we can't detect. In comparison, belief in God is something we introduced to satisfy ourselves, or to control others. Using a belief in God to justify a phenomenon is excessive: you are required to assume too much in order to explain the phenomenon that way, and as a result you accept information which doesn't directly help (and may interfere with) your understanding of the phenomenon. ("Why does the Foucault Pendulum's direction change? Because it's in God's plan." Doesn't really get you anywhere, does it?)

Third, ultimately it's quite likely that the Dark Matter theory will be proven, or disproven. If it's disproven, that'll likely mean we've achieved a new level of understanding of gravitational forces, in which Dark Matter is not needed as an explanation for the observed phenomena. Either way, for now, the theory acts as a guide for us to extend our knowledge. We can study phenomena and ask ourselves the question, "could the Dark Matter theory work in light of this evidence?"

A basic premise of the belief in God is generally the idea that the existence can't be proven or disproven: because things can be attributed to God even if we find perfectly plausible scientific explanations (like "Sure, we evolved, but that's just because God made it happen that way") and also because God supposedly exists at a level completely unreachable by our capabilities... And then if something like God did exist, there'd be no way for us to know whether this was or was not the God we recognized - because if this being has ultimate power over our universe, anything we can observe or measure is within its control, too.

So Dark Matter, while rather mysterious and sketchy as an idea, represents our best collective attempt to extend our understanding of the universe. And, ultimately, one way or another, it'll have helped us understand the workings of gravity and the universe. This is not true of God.

Re:Question.

[Atzanteol]

And this is different from believing in God... how, exactly?

Nobody has yet been killed for not believing in dark matter.

Re:Question.

[Doc Ruby]

We're testing for the dark matter. We can't test for god.

That's the difference between faith: knowledge not proveable (or disproveable); belief: knowledge dis/proveable, but not actually dis/proven; and fact: knowledge dis/proven.

The difference results in fact more reliable than faith, but faith more important than fact. The difference also means the two are compatible, even when apparently contradictory, but that faith must yield to fact when faith can still exist without being dis/proven as fact.

Re:Question.

[ajs]

So... Scientists can't explain how the universe works, without appealing to a mysterious phenomenon they can't observe and whose nature they cannot describe except in terms of its supposed secondary effects?

And this is different from believing in God... how, exactly?

I should think that would be obvious enough, but if you need an analogy, here's one:

A man walks into a dark room and stumbles over a chair. The chair bumps into something and there is a sound of something shattering.

Scenario 1: The man designates the "something" as "the glass ball", knowing full well that it may be neither glass, nor a ball. This is a way to talk about it with others. A placeholder, nothing more.

Scenario 2: The man asserts that there was a blue, Mexican blown glass ball on a table next to the chair, and that the blue ball was placed there my an older woman who will now want exactly $20.50 to replace it. Further the man asserts that anyone who claims that the ball was red is obviously wrong and their children should not be allowed to play with the children of such deviants.

Do you see the difference between the abitrary labels used as placeholders for observational gaps and religious dogma now? There's also the fact that there's math that suggests that dark matter exists, but that's actually a bit of a side point.

Also: keep in mind that dark matter is like a gap in current theory. If theory is revised in such a way as to narrow that gap to zero, then the need for the placeholder goes away, and everyone's happy.

Re:Question.

[Lord Ender]

So... Scientists can't explain how the universe works, without appealing to a mysterious phenomenon they can't observe and whose nature they cannot describe except in terms of its supposed secondary effects?

And this is different from believing in God... how, exactly?

How about: because there is evidence to suggest it exists. That's entirely different from believing in magic.

Seeing something move as if it is being pulled by gravity, and knowing that gravity is only known to come from matter, then conluding that there must be matter (or more fundamental theories are wrong) is called logic.

Re:Question.

[Knuckles]

And this is different from believing in God... how, exactly?

Dark Matter doesn't try to tell me whom to fuck or not.

Re:Question.

[AK Marc]

And this is different from believing in God... how, exactly?

One is testable, one is not. Just because proper tests haven't been invented yet to describe and identify dark matter does not mean it is not testable. Also, dark matter is predictive. One can presume its existance, then make a prediction based off that. Presuming God will make one win the lottery after a night of heavy praying will probably not be a good predictor of the winner of the lottery.

Re:Question.

[mrpolecat]

"And this is different from believing in God... how, exactly?" no one has mentioned Godel's Incompleteness Theorem yet... which taken to a logical conclusion would say that humans can't know about God. Apparently they're too stupid. Science starts from a position of ignorance. Religion starts from Omniscience. Or hubris

Re:Question.

[evilviper]

whereas when you seperate a Christian from God you get a rational thinking being.

Not at all. Irrational people will continue to believe what they always have, and continue to be irrational, whether or not religon is involed. It just gets popularly scapgoated, by people who have some ax to grind in the first place.

Re:Question.

[cbacba]

Religion and science have much more in common. Both require faith, however derived. Both have a basis in observation and interpretation. Both have their a' priori assumptions.

At the bottom, one can assume there is God or, one can assume there is no God. In the middle, one can assume god is an advanced space alien who terraformed the earth and genetically engineered earth based life. Ultimately, there are those who believe and there are those who don't know (agnostics). Athiests are merely yet more of the group who believe (that there is no God).

It is not possible to disprove that there is no God. Ultimately, one can only show that they are not, or at most, that God is not what they think He should be.

As for the dark matter, it is possible that there variations of matter which have never been observed by man. Most of what is seen in the popular press seems to be hype to enhance the status and bank accounts of those who promote it.

Whether dark matter (and energy) exists as something exotic or not is still a serious question. If dark matter exists in the quantities assumed, it's still possible that it might be normal matter which isn't absorbing or emitting sufficient light to be seen by us.

Currently, the suspected density of matter in the universe, including estimates for 'exotic' dark matter is the equivalent of about 6 hydrogen atoms per cubic meter.

Contrary to popular opinion, if black holes exist, the density of the matter it takes to form them depends on how much matter is involved and for a universe that is the size and mass of the one we think we live in, the size of the black hole turns out to be around 13.7 billion light years across. Such occurances rarely are coincidences.

The point is that there are usually a number of alternatives competing for position in science. The more exotic these are, the more they capture the imagination of people, and oftimes, the research grants. Let's face it, another Mars probe will probably do no better in TV ratings on the NASA cable channel than will the Star trek reruns a few channels down the dial.

I will look forward to hearing about this new press release. I think it will be interesting in some manner or another. However, since the press release infers that dark matter is something exotic and fundamentally different from normal matter, I'm pretty sure that the interesting part will be associated with being a gambit for funding and fame more than the announcement of something new and fundamental that changes our concepts forever.

I can still remember clinton horning in on NASAs public press pronouncement of life on Mars a number of years back. It seems a decade later that all their evidence has been shown that it is just as likely to be non life processes. Hence, it's back to the drawing board on that one. Is there, was there life on Mars - it still remains to be determined.

Of the curiousities of science, two are most interesting. First, the search for answers inevitably leads to more questions that need answering. Second, we periodically reach a point where it seems all is known except to add a few more bits of accuracy to the measurements - just before the lid blows off and we discover that momma nature wasn't who we thought she was at all.

Re:The whole day?

[MustardMan]

It says "noon"... maybe RTFS before trying for a first post?

Together again

[Petskull]

Now dark and normal matter will be one big family again, obviously with court supervision.

Re:The whole day?

[ZPWeeks]

...yep, I'm an idiot.... noon's a word, not a number. I read it, then looked again, and just saw "August 21 EMT." No interest in being a first poster. I almost never comment. sorry

Measure DM

[MECC]

As long as NASA doesn't try to measure DM in metric units, everything should go just fine.

Re:Measure DM

[Profane MuthaFucka]

If you don't get that joke, turn in your geek credentials. I dare say, even Star Jones would get that joke, so if you don't get it that's pretty bad.

In Soviet Russia 101

[192939495969798999]

In Soviet Russia, dark matter discovers YOU!

Although In Soviet Russia, the presentation would probably be posted before the story.

Re:The whole day?

[ackthpt]

August 21 Eastern Time? Wow, great.

This is news to announce there will be news at a later date.

the future will be here, any day now

Please record

[4solarisinfo]

Due to recent events at NASA, we'd appreciate everyone helping out by recording the stream of the event, and puttting it... well somewhere you can find it later.

Warp 1 Mr. Sulu

[OakDragon]

Cool! Now I can get started on my warp engine!

Yours, Zephram Cochrane

Re:Warp 1 Mr. Sulu

[Skynet]

Cool! Now I can get started on my warp engine!

Yours, Zephram Cochrane

That's anti-matter you nipplehead.

Re:Warp 1 Mr. Sulu

[spun]

I thought it was dork matter. As in, it only matters to dorks.

Re:Warp 1 Mr. Sulu

[Skynet]

ZING!

Re:Warp 1 Mr. Sulu

[Lisandro]

Best. Comeback. Ever :)

Re:Warp 1 Mr. Sulu

[bdonalds]

How did this not get modded "+5 Funny"? Well done, spun!

Re:Warp 1 Mr. Sulu

[spun]

Hehe, glad you didn't take it personally. It was just too good of a zinger to pass up :)

The importance

[eebra82]

So what's the matter, NASA?

Re:years of segrigation

[erotic piebald]

+2 Very Funny

Think that's bad?

[jd]

In recent studies of deuterium in the galaxy, they're finding less than 1/25th of what they're expecting, and almost entirely in the wrong places. They therefore conclude that there must be MORE than what they expect, but in a place/form that is invisible.

Will Hannibal Lector please stop eating the brains of astrophysicists.

Re:Think that's bad?

[wanerious]

IAAAstrophysicist, so perhaps a good chunk of my brain has been consumed already, but are you certain you mean *deuterium*? Is there a cite for this? I worked on galactic chemical evolution, and I'm a little out of touch with recent developments in the field, but this is news to me. Or maybe we're all really as dumb as you think we are.

Re:Think that's bad?

[The Great Pretender]

There was a recent article in Discover that profiled a physist (Mordehai Milgrom) who had come up with modification on Newtons law to explain the planets orbits (forgive me, I'm a layman in this but it seems that dark matter started as a way to explain the weird plant orbits in extended galaxies - I encourage you all to correct me).

"Mordehai Milgrom never wanted to be a heretic. Twenty-five years ago, while poking around for a meaty research problem, he found one that changed the course of his career--and that might yet transform our most fundamental understanding of the universe. His ideas, long relegated to the fringes of physics, where all but cranks fear to tread, have finally become too intriguing for his mainstream colleagues to ignore. Milgrom's heresy? He denies the existence of dark matter, the shadowy and thoroughly hypothetical stuff generally held to make up 80 percent or more of all matter in the universe. Even though dark matter has eluded all attempts at detection, most cosmologists are convinced it must be out there."

So potentially there may not be any dark matter and the vast money being spent on it's pursuit is being wasted. For the record I don't believe in string theory either. I have to say that I would love to subscribe to the simplicity of Milgroms ideas, but it's just a gut check that fitting the theory to the data is better than creating a fudge factor - which dark matter ultimately seems to be.

Re:Think that's bad?

[frankie]

JD, you need to provide a citation for that "Informative" comment of yours.

I suspect you're mistakenly referring to this study of deuterium near the galactic core, which says that the D-H ratio they found is consistent with other researchers' measurements that imply large amounts of dark matter.

Re:Think that's bad?

[HTH NE1]

They therefore conclude that there must be MORE [deuterium] than what they expect, but in a place/form that is invisible.

Please, don't let it be in the form of deuterium ore.

Re:Think that's bad?

[bla]

yes, sir. i am not the parent, nor am i an astrophysicist, but i just saw it this afternoon on cnn.com

clicky

Re:Think that's bad?

[jd]

Don't blame me, I merely read this stuff. :)

Re:Think that's bad?

[jd]

No, I'm referring to this story, which appears to be dated to yesterday - assuming the "monday" talked of was this week's monday. Your link is 6 years older - the date was 2000 - and looks like a completely different study.

Re:Think that's bad?

[Ana10g]

That sounds fantastic... something about Dark Matter always reminded me of Phlogiston, just a convient way of explaining what we don't know. Challenging the status quo on scientific matters is always a tough game though. IANAA, obviously.

Re:Think that's bad?

[frankie]

Current news, eh? Seems there are a lot of sites reporting on that. CNN (or any general-audience media) would not be my first choice for accurate reporting of hard science.

I'd recommend going to a science-specific magazine, or even a direct source.

And in any case, even the CNN article still doesn't say what you claim. For starters, there's nothing in there remotely close to "they're finding less than 1/25th of what they're expecting".

Re:Think that's bad?

[TrekkieGod]

I'm not an astrophysist, nor was I involved in the conversation before now, but I did read your linked article :)

Thanks for posting it, btw. I was taking what the parent said for granted, and it sounded pretty bad, but now it looks like it was a combination of bad reading comprehension and badly worded writing. The article you linked to at least, doesn't claim scientists are finding less deuterium than they expected and therefore expect more. Quite the contrary, they're finding a lot more than they expected, and thus are deciding that their theories need to be changed. I quote:

scientists had assumed that at least a third of the primordial deuterium present in the Milky Way was destroyed over time as it cycled through the stars...but FUSE found deuterium exists in amounts less than 15 percent below what was there originally.

So, they thought there were massive amounts of deuterium was "destroyed" and that not as much was left. Destroyed is a pretty bad way of describing it, but they allude to it in the article that what they mean by it is, "was transformed into heavier elements by stellar fusion." Instead, they're finding out that the amount of deuterium in the galaxy now is only about 15% less than what they thought was the original amount available. They also mention it being in unexpected places, or rather, not distributed evenly, which they find unusual according to current theories.

Nothing to complain about here. Seems to me that the astrophysicists still have their brains intact, and realize their theory needs to be tweaked if it doesn't match the evidence.

Re:Think that's bad?

[wanerious]

Ok, thanks for the link. I'll have to still dig up the original article, but it's a lot clearer.

In recent studies of deuterium in the galaxy, they're finding less than 1/25th of what they're expecting

According to the article, it's as much as 15% less than they were expecting. Not sure where 1/25 came from.

and almost entirely in the wrong places.

I don't know what you mean by "wrong", but if it's wrong for some isotopes to be trapped in grains, then a lot of them are in the "wrong" places. This has been supposed before, but I don't think anyone has detected it before now.

They therefore conclude that there must be MORE than what they expect, but in a place/form that is invisible.

You misread the article. This additional deuterium in the grains *gives* us more than we expected. Perhaps the nuclear reactions in some stars, or the rate of dredge-up before they eject their material, is somewhat different than we currently believe. Also, it is well-known that primordial material falls in on the disk of our spiral galaxy, so perhaps the rate of this infall is different (greater) from what used to be supposed.

Of course, we're all still probably idiots, so feel free to correct us after you're sufficiently amused by our floundering efforts.

Re:Think that's bad?

[geekoid]

there is an observastion that something is having an effect.

lensing indicates that it is not MOND.

Dark matter is just a term for something we don't understand having an effect we are observing, nothing more.

Re:Think that's bad?

[Jesrad]

According to B. Fraser, stars hardly do deuterium fusion at all, they do fission by breaking heavy elements into lighter ones (Fe, Ni mostly). He suggests a mechanism for the creation of (actually, a conversion into) heavy elements in outer space, that gravitationally collect into nebulaes and then stars, and fuel those stars.

Re:Think that's bad?

[The Great Pretender]

See now you have me answering from work, and I don't have the article in front of me, but didn't his collaborator Bekenstein define TeVeS, which is founded in MOND and potentially explains lensing? It was a lynchpin to the credibility of MOND.

All in the family...

[dbucowboy]

Dark matter... not to be confused with it's biggot brother, anti-matter.

Re:All in the family...

[gaspar ilom]

Just curious: are there any cosmologists/physicists theorizing about anti-dark-matter? (or "dark anti-matter"?)

It's not "dark" matter

[Billosaur]

We like to refer to it as "matter of color."

Re:It's not "dark" matter

[Mercuria]

I suspect even that will become passe soon, and we'll want to call it "Universal-American matter". This just proves Slashdot's (and NASA's) American bias, of course.

Re:It's not "dark" matter

[srblackbird]

I like to refer to it as "African-American matter"

*I'm black...

Re:It's not "dark" matter

[Panaflex]

I think Nasa lost some grey matter thinking that up.

Typo in title

[hacksoncode]

Shouldn't that be "NASA Announces *Announcement Of* Dark Matter Discovery"?

Re:Typo in title

[TigerNut]

How about "Slashdot Announces NASA Announces Announcement of Dark Matter Discovery"?

Re:Typo in title

[Alsee]

It's a "Dark Discovery". We cannot observe it directly, but only infer its existance based on its secondary media influence.

-

How does that make any sense?

[Pale-Horse-Rider]

How can one determine how "dark matter and light matter have been forced apart" when we haven't even conclusively determined the EXISTENCE of dark matter? Isn't that a bit like someone saying, "I've discovered why the Sasquatch hides from mankind?"

Re:How does that make any sense?

[geekoid]

we know something exist to be causing the effects seen, we just haven't observed it directly.

Come off it, you know what it feels like

[spun]

Dark matter feels just like hot grits when you put it in your pants, everyone knows that.

Re:Come off it, you know what it feels like

[geekoid]

but only with a petrified Natalie Portman.

August 21

[rolyatknarf]

And on monday August 21, 2006 at 12:00 PM CST WDAF Channel 4 Fox News in Kansas City will air an hour long program detailing the latest news, weather and sports for their local viewing area.

Details as yet are unclear as to the specific content.

Re:August 21

[geekoid]

it's called advertising.

Really, this is an annoucement so you can get into the telconference.

Re:August 21

[rolyatknarf]

"Really, this is an annoucement so you can get into the telconference."

There's going to be a teleconference before the noon newscast on 08/21/06? That never happened before to my knowledge. Could they know in advance that something of profound importance is going to happen that morning in the Kansas City area and it is being kept a secret until then?

Yawn

[geekmansworld]

This would be terribly interesting if dark matter actually existed and wasn't just a fudge factor necessitated by a poor understanding of how general relativity relates to quantum mechanics.

Re:Yawn

[geekmansworld]

I don't, no. But I still think it's hookum. And so do these peeps. Dark matter is a popular idea right now, that doesn't make it the right idea. I'll believe in dark matter when someone brings some back to Earth for show-and-tell day.

Peer review?

[Wormholio]

No announcement until Aug 21st? I guess that is how long they are allowing for the peer review of their results.

NOOooo...!!!

[The_REAL_DZA]

Someone's giving us ADVANCE NOTICE on Slashdot and you're COMPLAINING?!?!?!
 
I can't count how many times I've read something on Slashdot about something cool that's already happened, just barely, and said "Once again, information I could have put to much better use YESTERDAY!!!
 
Zonk, pay no attention to the criticism; I for one WELCOME some in-advance info (might even vote for it for "overlord"...)

Re:NOOooo...!!!

[psymastr]

I've noticed that at least 90% of criticism against /. is bullshit. It gets moderated up all the time though, probably because otherwise the poster would complain he got modded down because he spoke against /..

Re:NOOooo...!!!

[CarnivorousCoder]

"I can't count how many times I've read something on Slashdot about something cool that's already happened, just barely, and said "Once again, information I could have put to much better use YESTERDAY!!!"

You're right! I can put the knowledge of the announcement of a dark matter phenomenon to much better use today than if I wait for the actual details. Ok, the details won't really help me either once they're announced. :-)

Not at all

[Moraelin]

It's never been about how many planets are enough, and it's not just about Pluto. It's about how you define a planet.

It's, in a nutshell, about science: attempting to actually classify and understand the universe. Just proclaiming "ok, I hereby do dub Pluto a planet" is ok for everyday life, but a bit too vague for science. It's like you can talk generically about "radiation" in casual conversation or in super-hero comics, but to a scientist that's uselessly vague. A scientist will be more interested in what _kind_ of radiation (i.e., the exact particle), at what energies, etc.

The same happens in astrophysics. You can't just say "ooh, that's a pretty star", because that doesn't give you much to work with. Is it a planet? An asteroid? A comet? A star? A nova? A white dwarf? What? There are very good reasons to split hairs there, because out of such splitting hairs comes the understanding of what they are and how they work.

E.g., from the splitting of hairs as to how we classify stars came such categories as "white dwarf." In turn, that let us wonder about how big a white dwarf can be, which gave us the Chandrasekhar limit. In turn that told us that when a star goes over (actually it later it turned out that when it's just right under) that limit, it goes *KABOOM* in a spectacular Type Ia supernova. Since it happens at the exact same point, it tells us that every Type Ia supernova is exactly the same as any other one. Which in turn lets us use them to measure distances and velocities in distant galaxies. And from those came a bunch of other astrophysics stuff.

_That_ is why for science it's important to worry about such distinction. Sure, you can get through your everyday life without ever worrying about the difference between Pluto and an asteroid, or between a Type Ia and a Type 1b supernova. But for scientists, it's an entirely different situation.

The informal proclaiming which is what also doesn't scale. When you deal with a whole universe worth of stuff, you have a continuum of things, ranging from individual nuclei all the way to the super-massive black holes in the centre of galaxies. And there are trillions of trillions of them. You can't just go proclaiming for each and every single one of them if it's a planet, an asteroid, or what. You need some rule you can apply there.

Re:Not at all

[mooingyak]

Sure, you can get through your everyday life without ever worrying about the difference between Pluto and an asteroid, or between a Type Ia and a Type 1b supernova. But for scientists, it's an entirely different situation.

Does it really matter though? Planet, to my understanding, had historically been used to distinguish between observable objects in the night sky that move (planets) and don't move (stars).

I don't think that a planet is something that needs a precise definition. If there were some property that planets took on once they passed a certain threshold, and those properties or behaviors or whatever did not exist until that threshold was reached, then I might agree.

Re:Not at all

[ackthpt]

It's about how you define a planet.

It's also not about how you define a planet, but when.

Now that we're much more enlightened about cosmology, we decide we need more boxes to sort things into. Such as Planet and Near Object, where Planet used to suffice. This isn't about Pluto, it's about redefining Planet and then seeing what doesn't fit the new rules.

I find the practice a bit ridiculous in the case. Pluto is in the family of planets because that's what is familiar with most educated people. Sedna and Xena are a bit of a push because most educated people haven't heard of them and our literature and other media isn't full of references to them.

The case must be made that, should they determind Pluto doesn't fit the new requirement, Pluto be "grandfathered in" as an honourary member. The alternative is for astronomers to be labeled a bunch of squabbling nuts, like those who argue Shakespeare or Bacon. Whatever is decided, Pluto will go on, because it already has years of tradition in the cultures.

Re:Not at all

[Alsee]

Congratulations, you have just argued that there are Ten planets. That Ceres should be a planet "because it already has years of tradition in the cultures".

Ceres was assigned a planetary symbol, and remained listed as a planet in astronomy books and tables for about five decades, until several other asteroids were discovered. You are arguing that Pluto should continue to be listed as a planet for the SOLE reason that it has the same "tradition in the cultures" for about seven decades.

[Ceres/Pluto] is merely the first known and most famous [asteroid/Kuiper object]. [Ceres/Pluto] was called a planet for a few deecades because at the time there was no better catagory to lump it into. [Ceres/Pluto] was considered an oddball misfit amongst planets for several very good reasons. However we then discovered that there are thousands more [asteroids/Kuiper object], and that rather than being some ill fitting oddball planet, [Ceres/Pluto] is actually a perfectly fit member of a different non-planet group. That [Ceres/Pluto] is actually a a perfect fit meber of the [asteroid/Kupier object] group in the [asteroid belt / Kuiper belt].

Just because [you/they] learned in elemantary school that [Pluto/Ceres] was a planet, and [you/they] never heard of [Kuiper objects /asteroids] at the time, is not a valid reason to teach the next generation of kids a blatantly incorrect grouping.

Just imagine if your teacher has taught you that there are planets and there are asteroids, and that Ceres clearly belongs in the asteroid group, but that we are going to test you and require you to say that Ceres is a planet simply because we inadvertantly taught that incorrect information to kids last year and we don't want to fix the tests or the text books?

The only difference is that new we need to teach kids taht there are planets, plus the asteroid belt with thousands of asteroids, and there's the Kuiper belt with thousands of Kuiper objects. Teach kids that *ALL EIGHT* planets were formed in, and all orbit in, a strict planetary plane. Teach kids that Kuiper objects are ALL snowballs of frozen gas, and that they did NOT formed in the planetary disk with the planets, and that they do NOT lie in the planetary plane (except perhaps by sheer chance). That Pluto is a Kupier object because it lies out in the Kuiper belt, and because it is a snowball of frozen gas, because it did not form in the planetary disk with the planets and that it does not orbit in the disk of planets.

Pluto is not an oddball off kilter snowball of a planet outside the planetary disk, Pluto is simply an ordinary Kuiper object. The only noteable think about Pluto is that it is the first and most famous Kupir object, just as Ceres was the first and most famous asteroid.

"We know that dolphins are really mammals, but we 'grandfathered in' dolphins as an honourary member of fish".

-

Re:Not at all

[booksbookerman]

Muons,Neutrons,Quarks,Photons,Gravitons,Gluons,Bar yons,Quanta, Positrons,Hadrons,Leptons,Chaos,Neutrinos,Mesons,P rotons, Quasars,Pulsars,Gravitinos,Gamma rays,N=8,Time,Superstrings,10_eV,10_GeV,Entropy,Ha wking radiation,AND Schrodinger's cat. Where will it ever end?

Tanks for the Nemories

[Doc Ruby]

Most cold dark "matter" is dark energy, which in turn is dark information. The stuff that nemories are made of.

If this Chandra experiment is successful, we should hook it up to Google to search all the info we don't know about what didn't happen.

Re:Say What?

[The_REAL_DZA]

I can't get past the notion that when the submissions came in to name Uranus some panel member who wasn't paying particularly close attention might've looked up with a gasp and said "You want to name it after my what?!"

I can make my own dark matter

[i_ate_god]

1) Turn off lights
2) stub toe on matter I can not see
3) patent dark matter and the process by which to make it
4) ...
5) profit

Re:Say What?

[euice]

my anus never should be included.

Will Someone

[kahrytan]

Will someone please think of the poor helpless penguins !?!

Re:Will Someone

[LarsG]

Will someone please think of the poor helpless penguins !?!

Don't fret, they all got fat paychecks from the anti-Gore astroturfers.

**SPOILER**

[drxray]

They're referring to the Bullet Cluster. It's a merging system where a small cluster is passing through a large cluster leaving a shockwave that looks like a bullet's wake, hence the name.
Dark Matter is collionless, i.e. the DM from the smaller system hasn't been slowed down by the collion and just zooms through. The gas is slowed down. So, the DM and gas are no longer in the same place. We can see the gas in an X-ray telescope (Chandra) and detect the mass by the gravitational lensing effect on the background galaxies.
This is the first time that this has been shown, and it basically disproves the entire category of theories that DM is an illusional caused by us not understanding the action of gravity at long ranges (MOND).

Abstract from a conference talk about this. (PDF)

Re:**SPOILER**

[drxray]

My spelling sucks. I mean "collisionless", i.e. able to pass through other stuff without interacting. A bit like a neutrino.

-drxray

Re:**SPOILER**

[whitehatlurker]

Hmmm. That does make sense (after translation :-). The cluster's name (1E0657-56) is also used in the url on the NASA site (chandra.harvard.edu/photo/2006/1e0657/)

Re:**SPOILER**

[xiox]

Yes - it took me a few seconds to work out which observation they're talking about. There are so many nice Chandra cluster observations. I always have this problem understanding what the boiled down content in the press release is on about. However it is a very interesting cluster and a nice demonstration of the existence of dark matter. I was thoroughly convinced of the existence of dark matter by the talk anyway :-)

Re:**SPOILER**

[mako1138]

Thanks for the explanation. I just looked at arXiv, and there are several relevant papers to be found.

The most relevant is probably http://arxiv.org/abs/astro-ph/0309303 .

Re:**SPOILER**

[C0rinthian]

matter.exe -noclip

Re:**SPOILER**

[Celandine]

Actually there are a few other systems now where the weak lensing shows a mass distribution significantly different from the X-rays. You might have seen a few last week, though the point wasn't laboured.

Re:**SPOILER**

[Abcd1234]

This is the first time that this has been shown, and it basically disproves the entire category of theories that DM is an illusional caused by us not understanding the action of gravity at long ranges (MOND).

Umm... these observations only "disprove" MOND if you believe that MOND and dark matter are mutually exclusive theories.

Disclaimer: I hold no allegiences to either theory. I just find it irritating when people talk about "proving" or "disproving" theories when they're doing nothing of the kind.

Re:**SPOILER**

[LarsG]

So dark matter is IDSPISPOPD and IDBEHOLDI. Question is, is it IDDQD?

Re:**SPOILER**

[bigpat]

Thank you and I just read through the preprint, yours was a helpful summary.

I'd still be pretty skeptical about this observation disproving the hypothesis that "Dark Matter" is just a fudge of innacuracies in current gravitational theories, gravitational theories which we know are at best incomplete without a well tested unified theory.

I'd say a better bet to get some good gravitational data would be to try and explain the Pioneer anomoly with a purposefully designed deep space probe.

Re:**SPOILER**

[Mwahaha]

The preprint relevent to this article is http://arxiv.org/abs/astro-ph/0608407.

At first glance it seems like a nice paper.

Re:Prevailing theories

[gr8_phk]

also seem to think that stars orbiting a galactic center are supposed to obey Keplers laws... The discrepancy between the observed galactic rotation curves and the "predicted" one are then attributed to "Dark Matter" rather than someones poor understanding of basic physics.

The only dark matter is in these guys heads.

Re:Say What?

[ackthpt]

I can't get past the notion that when the submissions came in to name Uranus some panel member who wasn't paying particularly close attention might've looked up with a gasp and said "You want to name it after my what?!"

The father of Cronos? The joke was funny when I was 10. It's passe now.

Oblig. "insensitive clod"...

[The_REAL_DZA]

Hey, maybe I'm 10, you insensitive clod!!

sorry, couldn't resist (no, I didn't try very hard.)

Re:Question. (Mod Parent Down)

[Ralph Spoilsport]

It's not insightful. It's stupid. Why?

Because we can make tests and predictions that can or will prove or disprove notions of Dark Matter. No such test can be made for a God.

Parent is a Troll, Class A.

RS

A quick tutorial on Dark Matter

[MythoBeast]

Dark matter is something that effects things gravitationally, but doesn't emit or reflect any radiation. We can tell it's there because the galaxies hold themselves together. In fact, for the galaxies to hold themselves together it has to be something like nine times as common as normal visible matter.

So, if you shine a light on dark matter, nothing happens because the light passes right through it, possibly being defracted by the gravitational pull, but that's it.

The two biggest theories about what dark matter consists of are MACHOs and WIMPS.

MACHOs (MAssive Compact Halo Objects) are basically rocks floating in space that aren't big enough to ignite into a star (thus giving off light), and aren't close enough to another radiation source for us to see them. This theory is encouraged by findings that trans-neptunian objects are a whole lot more common than we thought they were, but is discouraged by the idea that these things don't float in and out of our solar system as often as we think they should.

WIMPs (Weakly Interactive Massive Particles), on the other hand, are a form of matter that just doesn't interact with normal matter except gravitationally. This theory is actually better supported than the MACHO one, but the reasoning is more complex. For instance, when you subtract all of the non-dark matter from our local dwarf galaxies they all turn out to have almost exactly the same amount of dark matter. There is no way to explain this with the MACHO theory. There is some evidence that individual WIMPs are 1000 light years across with a mass of 30 million suns, which is a tough thought to grasp.

Robert Rapplean
www.intellectualicebergs.org

Re:A quick tutorial on Dark Matter

[paralaxcreations]

The two biggest theories about what dark matter consists of are MACHOs and WIMPS.

This just proves my theory that the universe is a giant playground, and either you're taking lunch money, or giving it.

Re:A quick tutorial on Dark Matter

[LiquidCoooled]

Thanks for that Robert :)
Its left me with more questions, but in this life that is a good thing - it gives me something to do.

Dark Matter

[Lost Penguin]

Isn't this what a light bulb absorbs till it's full, and then you must throw it away?

Re:Dark Matter

[DanielG42]

How come LEDs absorb more dark matter?
After all, they are much smaller.

Re:Say What?

[twifosp]

There is a very specific reason why some do not consider Pluto a planet. One of the myths concerning this is based on Pluto's size. While Pluto is very tiny compared to the other planets, and is smaller than some Sol system moons, the size of Pluto is not an issue. What is an issue is what makes a planet a planet, and not some object captured in the sphere of gravity influence of a star. What makes a planet a planet, is that the matter that makes up the planet came from an initial star formation where when the star is violently born, it throws matter all about. This matter is traveling at high speeds and eventually coalesces again and forms planets. This is why all the planets share a fairly similar inclination and where they gain their orbital velocity. There were all born from the center of the Sun as it spewed matter during it's formation.

Pluto, on the other hand, doesn't share an orbit that could have been formed the same way the other planets have. In other words, it in all likely hood wasn't formed by Sol or in the Sol system. Due it its eccentric orbit, it seems more like it is an extra-Sol object captured by the Sun's gravity. Which makes it more of an Asteroid or Moon for the Sun rather than a planet.

Some reading:

http://en.wikipedia.org/wiki/Planet http://en.wikipedia.org/wiki/Pluto

Re:MOND and TeVeS in trouble?

[Halmos]

You beat me to it. But I can't help wondering if what they've "discovered" is just an even better way to support MOND.

How can one be certain that it's dark matter?

[Telephone Sanitizer]

The anouncement is supposed to be "how dark and normal matter have been forced apart in an extraordinarily energetic collision." So somebody is suggesting that dark matter moved, collided with non-dark matter and was forced away, releasing measurable energy in the process.

If nobody knows what dark matter is and if it can't be directly measured or detected then how does one go about measuring its motion and the energy released and know therefrom that it was dark matter that collided with the non-dark matter and not an altogether different unknown substance?

And if it was dark matter that collided with the non-dark matter then does this mean that it's no longer dark matter because it has now produced measurable energy?

Re:How can one be certain that it's dark matter?

[gardyloo]

If nobody knows what dark matter is and if it can't be directly measured or detected then how does one go about measuring its motion and the energy released and know therefrom that it was dark matter that collided with the non-dark matter and not an altogether different unknown substance?

      If there isn't a way to find out if it's "an altogether different unknown substance", then, for all intents and purposes (and sanity), it's not.
                                                                                              -Ockham

Re:How can one be certain that it's dark matter?

[spun]

Read the spoiler above. One cluster collided with another larger cluster. The gas and stars in the smaller cluster slowed down due to friction, the dark matter didn't. Now the dark matter and normal matter of the cluster are in two different places. We can tell the position of the dark matter from the gravitational lensing effect on galaxies behind it. Pretty amazing, and a major piece of evidence in favor of dark matter over MOND or TeVeS.

Re:How can one be certain that it's dark matter?

[maxwell demon]

If nobody knows what dark matter is and if it can't be directly measured or detected then how does one go about measuring its motion and the energy released and know therefrom that it was dark matter that collided with the non-dark matter and not an altogether different unknown substance?

Well, it's some substance we cannot see. Gravitating substance we cannot see is labeled "dark matter". So it cannot be "another substance" because that other substance would be dark matter anyway, by the very definition of "dark matter".

And if it was dark matter that collided with the non-dark matter then does this mean that it's no longer dark matter because it has now produced measurable energy?

Dark matter always has measurable energy (we measure it though its gravitational effect). Otherwise we wouldn't know about it. What dark matter doesn't do is to emit or absorb light. At least not enough for us to see it.

Re:How can one be certain that it's dark matter?

[ChrisA90278]

Appearently the collision was observed and i loks like the "normal" matter interacted like we all would expect but the dark matter interacted weakly with the normal mater and whent on a differntn tradjectory. We can see the normal mater and know where it is and we can see the effects of the dark matter's gravity on nearby normal matter and gues where it must be.

I'm thinking now that we might know something ore about dark matter. For example that it does not intercat electrically with normal mater. It is the electric force that makes it so two rocks bounce off each other and one does not pass through the other. It appears like maybe a "dark rock" could pass through nomal matter maybe. To actualy observe this effect would be a real milestone.

I'm just guessing from very little information. We all will see (or not) by the 21st.

Re:Prevailing theories

[dreamchaser]

It *is* possible that future advances in astrophysics and cosmology will nullify the dark matter argument. It's just as likely that there *is* some sort of mass carrying matter out that that we have yet to identify. Either way it just shows how much we have left to learn.

too bad this wasnt around nov 25

[kemo_by_the_kilo]

Would you like some Dark Matter or Light Matter?
legs or breast?

Re:too bad this wasnt around nov 25

[tillerman35]

Can I pay the extra 35 cents per baryon for an all-light matter universe?

Nice visual demonstration that dark matter exists

[riptalon]

I would assume this is the Bullet Cluster (1E 0657-56) combined X-ray and weak lensing results that Maxim reported at the Six Years of Science with Chandra Symposium last November. The interesting bit is that in this merging galaxy cluster the hot gas (~ 30%) has collided and been brought to a stop while the dark matter (~ 70%) haloes which are collisionless have passed through each other and are offset from the gas. By plotting the weak lensing image (which shows the total mass) over the X-ray image (which shows the baryons/gas) you can therefore see the existance of dark matter, since the mass is in a totally different place from the gas you can see in the X-ray. This isn't a fundamentally new result but it is a very nice visual demonstration of the existance of dark matter. Rotation curves of galaxies and the temperatures of galaxy clusters had proved it already but with this you don't need to do any maths you can just see it. Page 25 of this 6.5 MB pdf is the one you want for the image.

Re:Nice visual demonstration that dark matter exis

[SuperDuG]

I actually was about to say that, but you beat me to it.

Re:Say What?

[Teilo]

Funny that you mention that in this thread, because it is quite relevant.

Once upon a time, Pluto, in fact, was dark matter!

It was an object that was postulated to exist based upon gravitational anomolies in other bodies (Neptune), but which had not been directly observed. Obviously, Pluto has now been observed, thus it is no longer dark matter.

Some people have a mental block with the terminology "dark matter" as if it's some mystical substance. In fact it is a book-keeping tool, whereby the currently accepted laws of phycics are balanced against observation. If Pluto had been some strange force instead of a planet/planetoid (wait a minute, perhaps it is some mystical quantuum object that is both planet and planetoid at the same time, depending on who is observing it), the original observations would still be valid. An anomoly existed. The explanation just took some time.

Re:In case anyone is wondering what this is about

[C0rinthian]

Arghhh. Mispelled Apostrophe in parent. Must. Kill. AC.

Re:MOND and TeVeS in trouble?

[Celandine]

If the weak lensing observations are correct, and it's hard to see how they can be systematically wrong, then MOND is wrong (or, to cover bases, some aspect of our understanding of how to infer masses from *visible* matter is badly wrong). It's a neat result: no idea why it's getting a press release now, though...

Astronomers Make Important Dark Matter Discovery:

[omry_y]

its dark, but it doesn't matter.

Re:Prevailing theories

[Abcd1234]

So I presume you have a better understanding of "basic" physics? Good! Please point me to some of your research papers so I can educate myself.

Re:Say What?

[SmokeSerpent]

That's just plain stupid.

By your reasoning, if two solar systems passed close enough that one star captured a jupiter-sized body from the other star, you would not consider that body to be a planet anymore?

I love this place

[tyler23]

Why? Thanks for asking! I'll tell you.

Because, no matter how many people post pronouncements definitively proclaiming that they, as expert perl programmers or css jockeys or what-have-you, know *quite certainly* that the term "dark matter" is just meaningless mumbo-jumbo, demonstating their amazing mental superiority over the cretinous astrophysics community and its running-dog lackeys in the Mainstream Science Media, the emergent wisdom of the oft-maligned /. readership nonetheless mods the few informative posts up high enough that I can see them and therefore actually learn something interesting.

So thanks to drxray, and thanks to riptalon, and thanks to the readers who modded them up into my view.

Hyping machine for a science briefing?

[Baikala]

This atrangely resambles those cosole pre-release press conferences where nothing new of the product is said at all. Hype machine at work for a science briefing, what's next?

Is This an Advertisement?

[Rob Carr]

Is this an advertisement for Galactus pulling a tablecloth out from under dark matter dinnerwear on "The Universe Has Talent?"

Re:Say What?

[twifosp]

A planet of the new solar system? Well no. Planet of the old solar system? Obviously.

If this reasoning isn't sound, what seperates an asteroid from a planet? Mass? Size? No, there is a bit more to it than that. How the body was formed plays a large part in that, and if you've paid ANY attention to why Pluto's status as a planet was up for debate, you'll see that it's origins are the main topic of debate.

Please research what scientists call planetary formation before you call their reasoning stupid. It only makes you look silly and uninformed. http://en.wikipedia.org/wiki/Planet_formation

god bless

[mergatoriod]

Dark matter! what would we do without it...

Wonder what Mordehai Milgrom will be saying

[soxos]

Although the press release says nothing, I would assume that there is some good evidence pointing to the detection of dark matter.

In the August 2006 Discover magazine, there was an interesting piece about Mordehai Milgrom, a physicist who does not accept the dark matter theory. Basically, he has been able to retrofit Newton's equations to allow them to predict on the galactic scale (one of the reasons for the belief in dark matter). Being only an amateur physicist, I can't tell which method is the simpler, the one that only changes the equations, but (almost) no one buys, or the one that postulates the existence of matter that absorbs all electromagnetic energy. I can't wait to hear what this press release tells us.

Re:Wonder what Mordehai Milgrom will be saying

[Conor]

Dark matter does not absorb all electromagnetic energy! It merely floats around without emitting much electromagnetic energy. There's a big difference. It does interact gravitationally however, which is how it was identified.

Wild Dumb Idea

[smilindog2000]

As long as we're speculating about the discovery, let's not hold back! There's still debate as to whether anti-matter falls up or down. See:

        http://en.wikipedia.org/wiki/Wikipedia_talk:WikiPr oject_Physics/Archive4

If time slows down in gravity, it might speed-up in anti-gravity (the stuff that globs anti-matter together, yet repels regular matter). So here's a wild idea:

Maybe all the anti-matter didn't go away. Maybe it clumped together into large masses, spread out between galaxies. If so, it would help explain the acceleration of the expansion of the universe. If time for anti-matter were accelerated, perhaps all the antimatter stars burned out already, and went dark.

Then why stop there?

[Moraelin]

Then if you're willing to make a mockery of science by defining things by where culture put them, why stop there? Why bother having a science at all, for that matter? E.g.,

- at one point it was in the culture and literature, and all educated people knew, that the sun revolves around the earth, that there are no satellites except the moon, and that a cannonball twice as heavy falls twice as fast. That is, until that Galileo guy came and made a telescope, or actually dropped two cannonballs from a tower. So we should do... what? What do you propose? That for example Jupiter should have been honorarily proclaimed a planet without satellites, just to honour the tradition? That the heavier cannonball be honorarily proclaimed to fall faster, experimental values be damned?

- at one point it was in the culture and literature, and all educated people knew, that the earth is flat. Then came such people as Magellan who actually sailed around it. So what do you do there? Proclaim the Earth a honorary disc, just because that was the established mis-conception?

- at one point it was in the culture and literature, and all educated people knew, that everything is made out of 4 elements and the only thing that separates lead from gold is the proportion of those. I.e., that you could transform anything into anything else -- including the infamous lead-into-gold -- by just finding the right thing to mix it with, as to get the proportions just right for the target element. So we should have done... what, all along? Warped chemistry around that bogus notion, just to avoid upsetting the existing falsehoods? That instead of Mendeleev's table we should have a table with the proportions of the 4 elements for everything?

Etc.

Sad to break your illusions, but science is precisely about proving the existing theories false. That's _all_ that science is about: having nothing sacred or set in stone, and trying to prove the existing explanations false. It's _exactly_ about a "I don't care how many people already learned Newtonian mechanics in school, I don't care how much it would upset tradition to disprove Newton, I have a better theory and the data to support it" attitude. That's how every single discovery or progress have been made: someone had a better theory than the previous one.

The moment you start setting things in stone just because that's the pre-existing mis-conception, or caring more about winning popularity contests ("The alternative is for astronomers to be labeled a bunch of squabbling nuts"), that moment you're not doing science any more. Plain and simple.

I'll tell you what

[geekoid]

when we can sail to Pluto, we can revisit the issue.

How about this one.

[geekoid]

-Fry"This is a great, as long as you don't make me smell Uranus. Heh
heh."
-Leela "I don't get it."
-Professor "I'm sorry, Fry, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all."
-Fry "Oh. What's it called now?"
-Professor "Urectum."

Actual NASA Picture of Dark Matter

[Kent Simon]

Actual NASA Photograph of their Dark Matter discovery can be found Here

Advance notice, yes...

[leonbrooks]

...but it's too dark to see anything from here. (-: Them's grounds fer complaint! :-)

s/criticism against//

[leonbrooks]

...would make that read about right. (-:

Uh...

[leonbrooks]

...seconded.

(-: Just science keeping us in the dark again. :-)

People killed for not believing in dark bullets

[leonbrooks]

Your point was, again?

They do it cooler

[leonbrooks]

This means that they don't burn out as fast.

Re:Nice visual demonstration that dark matter exis

[John Baez]

Good work! I've put up some more links to Markevitch's work here, and a simplified explanation of this colliding galaxy business:

This Week's Finds, Week238

I'm not an expert on this, so some of the details could be wrong. I'll fix them if corrected (please send email).

Voila

[ackthpt]

Ceres is a planet. Again.

Oldest news trick in the book

[Wilson_6500]

Ahem.

"Can you see dark matter from your kitchen? Story at 11."