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The Starry Sky Just Got Starrier

samzenpus posted more than 3 years ago | from the twinkle-twinkle dept.

Space 186

An anonymous reader writes "Astronomers have surveyed eight elliptical galaxies, and found that we've vastly underestimated the number of dim red dwarf stars in these giant galaxies. When they used the new number of red dwarfs in their calculations, they tripled the total number of known stars in the universe."

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first? or third? (3, Interesting)

mug funky (910186) | more than 3 years ago | (#34411610)

dark matter much?

Re:first? or third? (2)

Fluffeh (1273756) | more than 3 years ago | (#34411652)

dark matter much?

Apparently less :)

Re:first? or third? (4, Interesting)

Nugoo (1794744) | more than 3 years ago | (#34411654)

To phrase that as a real question: What effect does this discovery have on the current estimates of the amount of dark matter in the universe?

Re:first? or third? (2)

spun (1352) | more than 3 years ago | (#34411678)

Good question. Assuming you are asking something along the lines of "How does this finding effect the ratio of dark to regular matter?" My guess is, not much, because I don't think the ratio ever really depended on observations of stars, per se.

Re:first? or third? (5, Insightful)

Hatta (162192) | more than 3 years ago | (#34411720)

Really? I thought that they used gravity to determine the approximate mass of the galaxy, and then subtracted the amount of visible matter to yield the amount of dark matter. If that's how they did it, then increasing the amount of visible matter would have to decrease the amount of dark matter.

Re:first? or third? (0)

Bemopolis (698691) | more than 3 years ago | (#34411800)

Yes, but the estimates give a ratio of dark-to-visible matter of 20 to 1 or so. Here they only triple the number of stars, and they are all on the low mass end of the scale, resulting in only a minor change in that ratio.

Re:first? or third? (4, Insightful)

Dekker3D (989692) | more than 3 years ago | (#34412062)

Actually, last I heard it was 5 to 1. So those tiny stars and any rocks orbiting them could have a bigger impact on those numbers than you think.

Re:first? or third? (3, Informative)

icebike (68054) | more than 3 years ago | (#34412262)

Five to one or twenty to one, you still have a significant amount of mass.

Then, as you mention, you have to add all the hard to detect planets for another small fraction. (If weren't seeing the star you can bet they weren't measuring its wobble). Admittedly its probably a small addition relative to the stars themselves.

Re:first? or third? (1)

fyngyrz (762201) | more than 3 years ago | (#34412768)

Darn it, modded you down, meant to mod you up, and the mod thang disappears after modding, so it can no longer be fixed. So, posting to undo the mod. Bloody broken slash-code.

Re:first? or third? (2)

mog007 (677810) | more than 3 years ago | (#34413076)

Rocks that orbit the stars are irrelevant for the purposes of mass calculation. All the mass in our solar system that isn't the Sun or Jupiter is less than Jupiter. Jupiter's mass is less than 1/1000th of the Sun's. Granted, our solar system may not be representative of other star systems, I bet it would be. Due to the process of stellar formation, there's always a shit-ton more Hydrogen and Helium than anything else.

Re:first? or third? (3, Informative)

wvmarle (1070040) | more than 3 years ago | (#34413342)

It probably depends on what you're talking about really, from WP:

dark matter accounts for 23% of the mass-energy density of the observable universe, while the ordinary matter accounts for only 4.6% (the remainder is attributed to dark energy).[2] From these figures, dark matter constitutes 80% of the matter in the universe, while ordinary matter makes up only 20%.

So ordinary matter accounts for 4.6% (1/20th) of all mass+energy in the universe - this I suppose has to do with Einstein's E=mc2 that allows for mass to be converted to energy and the other way around. And looking at actual mass, not taking the energy into account, this would end up at 1/5th. So both numbers are in a way correct, depending on context. I thought actually it was about 90% dark matter, so let's call that number the average. Then at least I'm not wrong myself.

Now I don't really know what they mean with the "dark energy" part or how that's measured, the "dark matter" I understand somewhat as it has to do with gravity.

Anyway this whole "dark matter" thing sounds to me like the hypothetical "aether" - we don't know what it is so make up something to make the formulas work. So now we found that there is 3-4 times as much "visible" matter in our universe than we thought before. Oh well that's quite some "dark matter" that has come to light. I'm quite sure the rest will follow sooner or later.

Re:first? or third? (3, Interesting)

Khenke (710763) | more than 3 years ago | (#34412206)

From Popular Science [popsci.com] you can read:
" 'Within these galaxies, a good chunk of the mass that had been ascribed to dark matter is probably stars,' said Pieter van Dokkum, the lead researcher on the project."

So I bet "a good chunk of the mass" is a bit more than "a minor change".
But we will probably soon get an exact new ratio after the smart guys have made new calculations, other than any of the above.

Re:first? or third? (2)

Nutria (679911) | more than 3 years ago | (#34412458)

after the smart guys have made new calculations

Bah.

Postulating Dark {Matter, Energy} is the height of hubris, since it implies that Astronomy Has Seen All There Is To See from our tiny little glasses on our tiny little rock in a backwater arm of the Galaxy.

Thank The FSM that there are still a few rational scientists out there actually *looking* for stuff.

Re:first? or third? (2)

hedwards (940851) | more than 3 years ago | (#34412518)

By that standard virtually all of science is based upon hubris as we haven't actually discovered everything there is to discover before coming up with hypothesis to test. By that measure it was arrogant of people to come up with the second without realizing that relativity is involved and that time doesn't exist at 0 kelvin.

Now, if you want legitimate arrogance, just look at those guys with their "string theory." It's been decades and they still haven't managed tho have a single testable hypothesis coincide with their ideas. A lot of things look good on paper as theory and then completely disintegrate when applied to the real world.

Re:first? or third? (1)

poopdeville (841677) | more than 3 years ago | (#34412630)

Now, if you want legitimate arrogance, just look at those guys with their "string theory." It's been decades and they still haven't managed tho have a single testable hypothesis coincide with their ideas. A lot of things look good on paper as theory and then completely disintegrate when applied to the real world.

String theory is the mathematical/logical synthesis of theories. As such, it can only predict what the logical closure of its sub-theories predict.

String theory cannot make any new testable hypotheses, because any testable hypotheses will be a testable hypothesis of the old sub-theory. String theory is still falsifiable: it is as falsifiable as General Relativity, Quantum theory, and the rest. Because it is them, taken together, and expressed in a unified mathematical framework.

Re:first? or third? (1)

drinkypoo (153816) | more than 3 years ago | (#34413134)

Because it is them, taken together, and expressed in a unified mathematical framework.

Don't you mean it's most of them, with small but important bits missing?

Re:first? or third? (2)

Khenke (710763) | more than 3 years ago | (#34412572)

It's just the opposite, Dark Matter is something we know we haven't seen, yet. It is a way to measure the "unexplored".

It's like saying that I know that of 20 persons in this room I can see 5 (and I can describe them).
If I have some way of knowing (gravity for example) that it must be equal to 20 persons, I can call the missing persons Dark People. They might be 15 normal people, its just that they are behind stuff (my self for example) so I cant see them straight on. I might catch a glimpse in a reflective surface and so on. But I might also have a number of persons and the rest are dogs, just because I haven't seen a dog doesn't mean there aren't any.

So Dark Matter might be known stuff (new stars like this) or unknown stuff (like the dogs).

Re:first? or third? (1)

Nutria (679911) | more than 3 years ago | (#34412684)

Just because you can't see the other 15 people, doesn't mean that you wouldn't see them if you had an IR camera.

Before Van Dokkum wrote his paper, the DM/DE proponents thought they'd found all the matter there is to find. Suddenly there's 3x more. Which is a slight reduction in the need for DM.

Who's to say that in 1-20 years other heretics find 10x more baryonic matter, thus reducing even more the necessity for DM.

Re:first? or third? (1)

mug funky (910186) | more than 3 years ago | (#34413080)

hang on, that's exactly what Khenke is saying...

astronomers/astrophysicists don't ascribe everything they don't know to "dark matter" in the sense that supernaturalists would say "God did it". dark matter is just a cool sounding name for stuff we can't see but we know it's there - ie the people or dogs or both in the room.

Re:first? or third? (5, Informative)

mog007 (677810) | more than 3 years ago | (#34413108)

Dark matter and dark energy are two totally different things. They're placeholders for vastly different phenomena. Dark matter explains why galaxies rotate at the speeds they do, even though their visible mass is much, MUCH, lower than the spinning speed shows it should be. Dark energy is the pressure that's causing the universe to accelerate outward. The universe isn't just expanding, the rate of the expansion is increasing, not decreasing as you would expect. Some force is being exerted on the fabric of the universe that's causing it to expand at a faster rate every second.

So, to recap:
Dark matter = mass that's causing galaxies to spin faster than they should be
Dark energy = force that's pushing the universe apart

Re:first? or third? (1)

drinkypoo (153816) | more than 3 years ago | (#34413144)

And finally, matter == energy, for anyone who wasn't confused already

Re:first? or third? (5, Insightful)

Chris Burke (6130) | more than 3 years ago | (#34413126)

Before Van Dokkum wrote his paper, the DM/DE proponents thought they'd found all the matter there is to find.

No astronomer thought they had found all the normal matter there is to find. In fact the search for dim red dwarfs in specific was part of trying to answer the Dark Matter mystery -- which originally only meant matter we had not seen yet, and only came to mostly refer to non-Baryonic Dark Matter when observations suggested that most of it was.

In fact, would you believe that when "DM Proporents" estimated the amount of non-Baryonic matter and added it to the known visible matter in galaxies, they still saw a discrepancy in observed gravity in elliptical galaxies? And that finding more normal matter was one prediction to explain it, and in fact this new observation may end up explaining the difference, solidifying our calculations of dark matter.

Suddenly there's 3x more. Which is a slight reduction in the need for DM.

3x the stars is not 3x the mass (particularly when the discovered stars are red dwarfs), but regardless...

Who's to say that in 1-20 years other heretics find 10x more baryonic matter, thus reducing even more the necessity for DM.

Indeed, who's to say? But as long as there are observations that cannot be explained by baryonic matter, it will be necessary.

I really like the characterization of this researcher as a "heretic", btw. I like it because this "heretic" was given access to the Keck Interferometer -- the combination of two of the largest telescopes in the world and thus a highly sought-after instrument -- in order to conduct his research. And then said research was published in Nature.

Because that's how we do things in science: we invite the "heretics" to make observations and disprove our current theories and hypothesis so we can create even better ones. They are not shunned, they are not shut out from access to the tools they would need to prove themselves,. Quite the opposite. Indeed, quite the opposite of a "Church" and "heretic" relationship. Which is why it's funny.

Re:first? or third? (2)

PopeRatzo (965947) | more than 3 years ago | (#34412662)

Thank The FSM

That reminds me. There's a few wags at my institution who like to send examples to a certain mailing list of kookie religious people being kookie. Someone posted a discussion on a Christian web site of some fundamentalist "physicists" talking about how the reason regular physicists had to invent dark matter is because they weren't taking into account the mass of Heaven and Hell.

I am not making this up. When I get time I'll try to find the link and I'll post it to a journal here. Some of you godless heathens might get a kick out of it.

Re:first? or third? (5, Insightful)

Chris Burke (6130) | more than 3 years ago | (#34412916)

Postulating Dark {Matter, Energy} is the height of hubris, since it implies that Astronomy Has Seen All There Is To See from our tiny little glasses on our tiny little rock in a backwater arm of the Galaxy.

Thank The FSM that there are still a few rational scientists out there actually *looking* for stuff.

There are observations that have been made which cannot be explained by any quantity of unseen "regular" aka Baryonic matter. This is the result of people actually looking for stuff, and not in their hubris assuming that we have Seen All There Is To See. Indeed it is very much a case of realizing that we have not seen it all.

Hubris is dismissing (the non-Baryonic subset of) Dark Matter because it's not the same as the "regular" matter we are familiar with in a much more extreme case of assuming we have Seen All There Is To See. Red dwarfs are nothing new; and you're strongly implying you think such examples of normal objects will explain away the need for Dark Matter, as in we won't find anything new. We Have Seen It All.

Even though what astronomers have seen strongly suggests that is not true, and there is stuff out there completely different than what you are comfortable with.

It is kinda funny how often people give "arrogance" as the reason why scientists put forward certain hypothesis when they are completely unaware of the actual scientific reasoning behind the hypothesis. By attributing arrogance to others as a consequence of their own ignorance, they demonstrate tremendous hubris.

Re:first? or third? (1)

Bemopolis (698691) | more than 3 years ago | (#34412552)

Wrong. The canonical number used in galaxy modelling is 20-to-1. That number is inferred from the rotation curves of spiral galaxies, not ellipticals, but that's the ballpark. And then there' this:

"But there’s still plenty of dark matter, too, according to van Dokkum. In fact, the new stars probably won’t change the accounting of dark matter very much."

But hey, look at me being lazy and just quoting the article you cited.

Re:first? or third? (1)

Khenke (710763) | more than 3 years ago | (#34412672)

Depends on what we call "a good chunk", "a minor change", "not very much".
A change to 19 to 1 from 20 to 1 might be any of the above (not that I'm saying that the change will be that or even close).

For us mortals the change might be minor, but for a scientist it might be a huge change.

Re:first? or third? (1, Insightful)

poopdeville (841677) | more than 3 years ago | (#34412530)

You're ignoring something important. The laws of conservation of matter and energy.

These are stars that went supernova, but for which the remaining gravitationally bound matter did not turn into a black hole. It takes a lot of matter for a star to nova, and it doesn't just disappear.

In short, they tripled the number of stars that were at one time on the order of 10 times more massive than average.

Re:first? or third? (1)

poopdeville (841677) | more than 3 years ago | (#34412568)

Nevermind, I'm wrong about red dwarves.

Re:first? or third? (1)

techno-vampire (666512) | more than 3 years ago | (#34412606)

These are stars that went supernova, but for which the remaining gravitationally bound matter did not turn into a black hole.

In a word, no. Supernovas that don't turn into black holes end up as neutron stars, not red dwarfs. Red dwarfs are the remains of stars too small to go supernova, which is why they're so small.

Re:first? or third? (3, Funny)

PopeRatzo (965947) | more than 3 years ago | (#34412674)

You're ignoring something important. The laws of conservation of matter and energy.

Important to you, maybe...

Re:first? or third? (2)

arth1 (260657) | more than 3 years ago | (#34411842)

Minor corrections:
- Not only the visual spectrum, but the entire electromagnetic spectrum.
- Black holes are also added to the baryonic matter count, and their masses are estimated based on their effect on observable matter. For faraway objects, one can assume that the number and sizes of black holes compared to visible matter is lower than the ratio in our neighbourhood, simply because faraway galaxies are much younger, giving black holes less time to appear and grow.

Anyhow, I see this as good news for our descendants. Red and brown dwarves are likely better targets for extrasolar exploration than bigger stars are.

Re:first? or third? (3, Informative)

John Hasler (414242) | more than 3 years ago | (#34411864)

They don't determine the mass of a galaxy by counting stars.

Re:first? or third? (0)

Nugoo (1794744) | more than 3 years ago | (#34412720)

He doesn't say that they do. He's saying they determine the mass of a galaxy some way, and count the starts to see if it matches up with what they determined, adding dark matter to account for the rest.

Re:first? or third? (1)

Bigjeff5 (1143585) | more than 3 years ago | (#34411900)

You are correct, but the amount of dark matter figured in this way was roughly four times the amount of visible matter. A full tripling of visible matter (which is not what happened - these are teeny tiny stars, which is why they were missed before) would only set dark and visible matter roughly equal to each other.

Re:first? or third? (1)

icebike (68054) | more than 3 years ago | (#34412380)

Teeny tiny is a relative term.

Up to 40% of the mass of the our sun is the usually quoted cut off for red dwarfs. That is still a pretty sizable object.
Two or three of these add up to our sun.

An interesting visual of relative solar system masses is here
http://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size [wikipedia.org]

Re:first? or third? (1)

Denihil (1208200) | more than 3 years ago | (#34412522)

nice link icebike! is it just me, or is there a irresistible urge to put "your mom" in "Examples of objects between 20 km and 1 km in radius" list and see if anyone notices?

Re:first? or third? (1)

icebike (68054) | more than 3 years ago | (#34412586)

I'm afraid your referential opacity places you squarely in the realm of dim matter.

Re:first? or third? (1)

Denihil (1208200) | more than 3 years ago | (#34412924)

Zing! Your excessive use of big words along with a obligatory astronomy reference clearly shows that your sense of humour is fundamentally superior.

Re:first? or third? (2)

aristotle-dude (626586) | more than 3 years ago | (#34411742)

Good question. Assuming you are asking something along the lines of "How does this finding effect the ratio of dark to regular matter?" My guess is, not much, because I don't think the ratio ever really depended on observations of stars, per se.

What was the need for there to be dark matter in the first place? Wasn't it invented as a concept to explain why the universe is the way it is assuming it has a specific amount of stars in it? Has anyone proven that dark matter exists or is it just a convenient kludge to make a model of the universe fit observations?

If they discovered that there are 3 times as many stars as previously believed then what purpose does the concept of dark matter serve?

Re:first? or third? (1)

mug funky (910186) | more than 3 years ago | (#34411810)

If they discovered that there are 3 times as many stars as previously believed then what purpose does the concept of dark matter serve?

the other ~70% of the observed mass... 3 times the stars still means a lot of dark matter.

dark matter isn't something intangible. it's matter with not enough light bouncing off it for us to see.

Re:first? or third? (2)

fyngyrz (762201) | more than 3 years ago | (#34412818)

dark matter isn't something intangible. it's matter with not enough light bouncing off it for us to see.

Not quite. It's just matter we haven't seen and so can't account for, if we have the mass estimates for the universe right, which is in itself doubtful. For instance, a small galaxy directly behind a large one in a position that doesn't allow us to see it -- that's "dark" from the dark matter point of view, even though it's glowing like crazy. Some of it might not be radiating, or radiating too dimly; but on the other hand, our math may just be entirely wrong.

Re:first? or third? (2)

abigor (540274) | more than 3 years ago | (#34411830)

Non-baryonic dark matter has to exist in order for certain observations made on the cosmic background radiation to make sense. Basically, the Big Bang couldn't have happened without it. There's a lot more to it than just missing mass.

As for evidence, there's enough to infer it exists, but its exact composition remains elusive, so far as I know with my layman's understanding of this stuff.

Re:first? or third? (2)

lgw (121541) | more than 3 years ago | (#34412068)

The best evidence is that, by observing galaxy rotations, it seemed like the galaxies needed to be about 80% dark matter for the rotations to make sense (there were several competing theories at that point). Then the CMBR observations pegged the composition of the universe at that early time at about 80% dark matter. The unrealted theories agreed to a couple of significant digits, which pretty much settled the matter (as much as anything in cosmology can ever be known).

Re:first? or third? (1)

Fluffeh (1273756) | more than 3 years ago | (#34412356)

I explained the need for Dark Matter previously here on /. [slashdot.org] and folks seemed to like the explanation so I am reposting:

It is something more along the lines of this: We have a good number of formulas and calculations that work properly with the things we can measure - planets, the sun, cars, planes, kitchen scales. One of these might be:
y + 3 = 5
Nice and simple for this example. Lets say that the "y" here represents gravity and the formula has been proven in every experiment we have done.
We therefore assume that this calculation is correct and true. BUT when we try to use this calculation when looking at things like galaxies, we seem to find the wrong answer:
y + 3 = 7.2
This is clearly not correct, but as we don't want to throw out all the formulas and understanding we have about how things work, we add another variable to the formula like so:
y + 3 + x = 5
The "y" still represents gravity, but now we add the "x" which represents something we don't understand and we don't know where it came from. We call it Dark Matter because we can't see it, don't seem to be able to interact with it and have no real idea of what it is - but with this new addition to the formula, the answer once again comes out at what we know (think) to be true. We just now need to find what this x variable is.

THAT is why finding/understanding Dark Matter (and on that note, Dark Energy) is so important. We know (think we know) the right answers, but our formulas just don't seem to fit so well when applied to certain really, really, really big things (like clusters, superclusters etc). When we find this "x" in the formula, it will once again work perfectly for all our calculations.

Re:first? or third? (1)

Man On Pink Corner (1089867) | more than 3 years ago | (#34413366)

So why was it wrong for Einstein to add Cosmological Fudge Factor X to the equation, but not for us? How do we know, or what makes us think, that the missing matter is non-baryonic in nature?

Re:first? or third? (1)

fyngyrz (762201) | more than 3 years ago | (#34412936)

Basically, the Big Bang couldn't have happened without it.

Well, considering that nothing in our physics confirms that the big bang even COULD have happened, I'm pretty comfortable with not assuming invisible things exist to back up an hypothesis that isn't possible under normal physics anyway. The big bang is just hand-waving at this point in time.

Ascribing it the status of certainty is the result of not consuming the available objective facts, in particular that the states described for the important part of it aren't possible under any configuration of reality we understand.

So it's either wrong (quite possible) or else there's a good bit of science to come before we can confirm it's right.

As for the rotation rates of certain galaxies, that is integral to the mass, and it's not at all clear that we've got mass estimates right as yet, either. Every example we have is in our galaxy, and in our local stellar neighborhood. Those values may hold elsewhere, or they may not. There may be other forces (see the Pioneer anomaly, for one) or there may not. Just too soon to be sure on several fronts. Considering that at least two major forces are only visible to us by their effects (gravity, magnetism), it may be optimistic to presume that there aren't others, especially when the scales change from our local experience to one the size of a galaxy, or spanning many galaxies. Look at the strong atomic force; on a small scale, it's a ripper; across ten feet... means absolutely nothing. We may simply not be able to measure something that is going on because of scale.

And it isn't that I have anything against the idea of matter we can't see. On the contrary, I'm sure there's plenty of that. It's just this assumption of already-settled-truth WRT the big bang that irks me. If it's settled in your mind, then I assure you, you don't understand it. Ask a cosmologist -- they'll be the first to tell you the same thing.

Re:first? or third? (4, Insightful)

Chris Burke (6130) | more than 3 years ago | (#34413160)

The big bang is just hand-waving at this point in time.

Hand-waving, one of the most successfully predictive theories [xkcd.com] of the last century, these are both the same. I'll make them seem like they're both the same by... wait for it... waving my hands.

Re:first? or third? (1)

Albinoman (584294) | more than 3 years ago | (#34411854)

True, Dark Matter, like Dark Energy, is just a placeholder name for something that we know is there. What we're seeing is patches of gravity where none should exist. Even with all those red dwarfs being added it still doesn't come close to making up for all the extra gravity. I heard Neil deGrasse Tyson say at a lecture (which certainly could be outdated) that observable mass accounts for about %5 of of all the stuff out there.

Re:first? or third? (5, Interesting)

UnknownSoldier (67820) | more than 3 years ago | (#34412030)

> True, Dark Matter, like Dark Energy, is just a placeholder name for something that we _think_ is there.

FTFY.

Probably will get modded down, but if you "knew" it, then you would be able to prove it exists. Since no one has seen it, touched it, tasted it, smelt it, or felt it, therefore it is a mathematical kludge, aka, the aether of the 1900s. (Yes, I'm aware of http://www.nasa.gov/home/hqnews/2006/aug/HQ_06297_CHANDRA_Dark_Matter.html [nasa.gov] )

Ergo, while said more politely, "it falls out of the math", which will allthough appear quite reasonable at first, given the current limitations of understanding gravity / light / mass & energy, it is still one a big hack-job based on one assumption after another, namely:
  a) that there is only one type of gravity and
  b) gravity is universal (which is a little preposterous / pretentious to base how the WHOLE universe works based on one tiny little planet.)
  c) redshift is accurate (ARP has interesting evidence that calls into question this assumption)

This prof. provides a half-decent summary though:
http://zebu.uoregon.edu/1999/ph123/lec08.html [uoregon.edu]

Re:first? or third? (3, Insightful)

geekoid (135745) | more than 3 years ago | (#34412138)

Since they can make predictions with it, and have tons a data supporting there is an effect going on, you're wrong.

"Since no one has seen it, touched it, tasted it, smelt it, or felt it."

the same can be said for gravity.

Now if you added 'measured it' then it couldn't be said for gravity. Of course then it couldn't be said for dark energy and dark matter.

a) There is no evidence of any other kind. Should some good evidence actually come in, then great.

b) Every measurement we have made using our understanding of gravity seems consistent. Again, if there is actual evidence of something else, then thing will change.

c) interesting evidences doesn't matter, strong* evidence does.

Your post shows a large amount of ignorance on this matter, and ignorance on the scientific process.

*no pun intended.

Re:first? or third? (1)

Nemyst (1383049) | more than 3 years ago | (#34412830)

Sorry, but the Ptolemaic system was, back in ancient times, a very accurate representation of planetary movements. From your first line, then, Galileo would be wrong.

There always needs to be a sufficient amount of skepticism to everything we devise. Dark matter really is aether. We don't know what it is, we can't observe it so far, the only thing we know is the effects it does. However, interesting theories (such as Hoava–Lifshitz gravity [wikipedia.org] ) have sprung up that try to explain the effects we see without requiring the intervention of an exotic matter/energy mix. In many ways, the situation is similar to the birth of relativity.

Re:first? or third? (0)

Anonymous Coward | more than 3 years ago | (#34413218)

b) Every measurement we have made using our understanding of gravity seems consistent. Again, if there is actual evidence of something else, then thing will change.

Except for all of the measurements that led to coming up with the concept of "dark matter." We'll have to see if the dark matter concept actually hangs together consistently.

Re:first? or third? (1)

SteveFoerster (136027) | more than 3 years ago | (#34413262)

"Since no one has seen it, touched it, tasted it, smelt it, or felt it."

the same can be said for gravity.

Really? Where do you live? I feel gravity constantly.

Re:first? or third? (5, Informative)

spun (1352) | more than 3 years ago | (#34412142)

No, it's out there. Things like the bullet cluster pretty much prove that there must be large amounts of some sort of weakly interacting matter. Basically, two galaxies collide. Normal matter in one galaxy interacts with normal mater in the other, slowing it down. But something massive wasn't slowed down and kept right on trucking along the same path at the same speed as before. We only know it is there because of the gravitational lensing it produces. So, we have direct evidence of matter that we can not see, and that does not interact with other stuff except through gravity. Call it whatever you like, it's out there. And that is just one piece of evidence. Galaxy rotation and the CMB are others.

Re:first? or third? (1)

Nutria (679911) | more than 3 years ago | (#34412590)

Call it whatever you like

How about "really dim baryonic matter". After all, we're Really, Really Far Away.

Re:first? or third? (2)

spun (1352) | more than 3 years ago | (#34412640)

Really dim baryonic matter would only explain some of the many different lines of evidence.

I don't really have a horse in this race, I mean, I could care less which theory turns out to be correct. It just seems like the preponderance of evidence points to a non-baryonic source of mass at this point.

Re: first? or third? (1)

Black Parrot (19622) | more than 3 years ago | (#34413002)

I don't really have a horse in this race, I mean, I could care less which theory turns out to be correct.

Me neither. But it really seems odd that so many Slashdotters are so rabidly against the idea of dark matter.

Re: first? or third? (3, Interesting)

drinkypoo (153816) | more than 3 years ago | (#34413172)

Me neither. But it really seems odd that so many Slashdotters are so rabidly against the idea of dark matter.

The story of humanity is full of whole chapters which basically boil down to a bright spark being smothered by a bunch of ignorant fuckwads attached to their idea of how the world works. Every once in a great while the spark lands in a pile of tinder not in the furnace-equipped basement of a firetrap and something wonderful is born, but mostly people shun what they don't understand and it's their children or their children's children who are willing to incorporate it into their lives as an escape from the previous generation who doesn't "get it". This is why the technological singularity is the religion most appealing to the technological elite...

Re:first? or third? (1)

ghostdoc (1235612) | more than 3 years ago | (#34412982)

Or things like the Bullet Cluster prove that we don't understand gravity nearly as well as we think we do.

Put simply: two things interact, but don't conform to our expectations of how they should interact. Therefore:
1. Our expectations must be wrong.
or
2. There must be something we're not seeing about the interaction.

Dark Matter is basically saying "2, because our expectations seem to pan out for other interactions"

But then...Dark Energy...

Put simply: two things interact at very long distances, but don't conform to our expectations of how they should interact. Therefore:
1. Our expectations must be wrong.
or
2. There must be something we're not seeing about the interaction.

So, non-intuitively, we say "2 again, despite the thing we're not seeing being completely different/opposite to the thing we didn't see with Dark Matter"

Of course, redoing the assumptions about gravity at galactic scales will be hard, and there won't be any megabuck research grants and facilities to do it, so I don't really blame people for not wanting to go down that path...

Re:first? or third? (1)

Angst Badger (8636) | more than 3 years ago | (#34412294)

gravity is universal (which is a little preposterous / pretentious to base how the WHOLE universe works based on one tiny little planet.)

It would be, except that our observations of the effects of gravity cover countless measurements over the entire observable universe.

Re:first? or third? (1)

melikamp (631205) | more than 3 years ago | (#34411954)

IANOP, but this galaxy is 90% dark matter is just another way of saying that the amount of matter visible to us as stars and interstellar gas is dreadfully insufficient to account for how this galaxy rotates, even if we generously account for very dim collapsed stars and stellar black holes, for as many of them as we think have appeared since the Big Bang. Either General Relativity is wrong on a galactic scale, or there is a crap-ton of matter hanging out there that does not produce, block, or reflect any light. The "visible" matter is mainly just stars and interstellar gas, and is composed of familiar protons, neutrons, and electrons. Dark matter, whatever it is, is probably radically different from anything we've encountered so far, although alternative laws of gravity and halos of massive dark objects such as black holes are not totally ruled out.

Re:first? or third? (1)

fyngyrz (762201) | more than 3 years ago | (#34412984)

or there is a crap-ton of matter hanging out there that does not produce, block, or reflect any light.

...or there is something blocking the light it is emitting from getting to us. Or... the universe isn't the kind of lumpy they assume it is (there may be another scale of lumpiness beyond where we can see it.) Or we've got the mass estimates wrong. Or there is another force we're not accounting for. Or the forces we know don't act the way we think they act over large scales (20:1, after all, isn't much on a log scale. And guess how we characterize things like gravity and magnetism?) Or something we have no experience with at all. Or some combination of the foregoing.

Re:first? or third? (5, Interesting)

spun (1352) | more than 3 years ago | (#34412056)

I believe this [wikipedia.org] is one piece of very strong evidence for some sort of pervasive weakly interacting massive stuff. Two galaxies collide. The normal matter interacts with other normal matter and slows down, The "other stuff" does not interact, and keeps moving. We know it is there because it creates a gravitational lens. If the lensing were caused by any sort of matter that interacted with other matter, these lenses would not be located where they are.

So the theory of Dark Matter is more than just "there is more stuff than we can see." We can see specific phenomenon that normal matter just can not produce.

Re:first? or third? (1)

HornWumpus (783565) | more than 3 years ago | (#34412488)

Your incorrectly summarize your own cite.

Two galaxies collide. The stars are slowed by gravity but mostly go on their way, the gasses collide and slow down while emitting X-rays, some other stuff does not interact and keeps moving.We know it is there because it creates a gravitational lens. That lens is detected in the same place as the visible stars but has no observable light.

Further from your cite

Critics of dark matter have cautioned that astronomers expect sizable quantities of non-luminous baryonic matter to reside in large galactic clusters, positing that the Bullet Cluster phenomenon can be explained without requiring non-baryonic dark matter.[13] However, this explanation requires that baryonic dark matter is of the same amount as the luminous baryonic matter in the Bullet Cluster. This means that ~6 times the visible galactic mass exists at the gravitational centroids, possibly in the galaxies as MACHOs, brown dwarves, or cold gas clouds.

Re:first? or third? (1)

spun (1352) | more than 3 years ago | (#34412620)

Sorry, got the bit wrong about the stars. But how could cold gas clouds not smash into each other? And why does this observation match up with so many others that also show the existence of dark matter? Critics like to take each piece of evidence separately, and cast doubt on each one, but they rarely seem to want to take on the whole package of evidence at once.

Re:first? or third? (1)

fyngyrz (762201) | more than 3 years ago | (#34413012)

The extra mass could simply be a much larger black hole in the incoming galaxy that had previously consumed most of it's surrounding matter. There's just too much that isn't known here to draw firm conclusions about anything.

Re:first? or third? (1)

zdepthcharge (1792770) | more than 3 years ago | (#34412664)

The obvious question (at least to me) is that other than creating a gravitational lens, how did the dark matter gravitational interact with the normal matter? Shouldn't there be some deviation in the path of the normal matter due to the gravitational effect of the dark matter? Did it simply slow the normal matter down more than would be expected in a normal matter to normal matter collision? The article you link to mentions that this example does not shed any light on the galaxy rotation problem that gave birth to the idea (not theory!) of dark matter. In any case, this is a just a data point. For this to be a useful data point, we need examples (at the same scale) of pure normal matter interactions. Or a whole new idea.

Re:first? or third? (2)

Truth is life (1184975) | more than 3 years ago | (#34412958)

The galaxy rotation problem is basically this: Stars towards the edge of galaxies (mainly spiral galaxies) rotate much faster than they should based on Newtonian gravitation using only the visible material (the Einstein corrections are negligible at the speeds and distances being talked about, so they can't account for the differences). To explain this, you have basically two options: MOND, MOdified Newtonian Dynamics (ie., changing the laws of the universe at large distance scales like kiloparsecs), or dark matter (which can include baryonic dark matter as well, but generally refers to non-baryonic things), which corrects for it by assuming that there's a vast halo of objects that outweighs everything else in the galaxy and thus speeds up the rotation of objects far away from the galactic core.

The evidence at the moment seems to be in favor of dark matter, and in any event I have some doubt that we will ever see "examples at the same scale of pure baryonic matter interactions" as you put it; it may be that the phenomena in question are simply things that appear on the very large scale and aren't observable on the small scale, just the same way that relativity only becomes important under certain conditions and Newtonian dynamics works perfectly well in our "normal" world. (But I'm not an astrophysicist, just aiming to be one!)

Re:first? or third? (1)

wvmarle (1070040) | more than 3 years ago | (#34413412)

So this "other stuff" is there, does not interact with itself, but does interact with OTHER matter (light in this case) to create a gravity lens?

I may miss something but to me it seems to contradict. How can its gravity interact with light, but not with itself or the non-dark matter in those colliding galaxies? If it produces that much gravity to create a gravitational lens, why doesn't it pull the rest of the galaxy with it?

Dark matter interacts or it doesn't. It holds galaxies together, creates gravitational lenses, but doesn't interact with itself nor with other galaxies.

Re:first? or third? (1, Informative)

Bigjeff5 (1143585) | more than 3 years ago | (#34411892)

It won't boost as much as you think. It increases the number of stars, but red dwarfs are small and not very massive. They are usually stars that went nova but were too small to collapse and form a black hole.

A handful of super-massive black holes could probably cover this tripling of the stars.

Even if the amount of matter tripled, however, it still would not eliminate dark matter. Currently, visible matter accounts for 4.6% of the matter in the observable universe. Dark matter accounts for 23% (the rest is dark energy). Tripling the visible matter would bump it up to 13.8% of matter in the universe, and would bring dark matter down to 13.8%, or roughly equal.

That's still a hell of a lot of dark matter that is currently invisible, and is still plenty to screw up astronomical observations.

Re:first? or third? (1)

ByteSlicer (735276) | more than 3 years ago | (#34412472)

red dwarfs are small and not very massive. They are usually stars that went nova but were too small to collapse and form a black hole.

That's incorrect. Red dwarfs do not have enough mass to go nova. They just slowly burn up their nuclear fuel until they cool off. And it takes a supernova to create a neutron star or black hole. A nova is a less energetic phenomenon where one star steals gas from a companion star, until the density/temperature becomes critical and the star's surface layer is blast away in a fusion reaction. In many cases this can be repeated several times, since most of the star survives.

Re:first? or third? (0)

CheshireCatCO (185193) | more than 3 years ago | (#34412382)

In addition to what others have said about large stars probably mattering more than small ones and about how much dark matter out-masses luminous matter, there's another thing to consider. Namely, most luminous matter in a galaxy is in the form of gas and dust and not stars. So increasing the number of red dwarfs does far less than triple the contribution of luminous matter to the universe's total mass.

My god . . . (4, Funny)

Mitchell314 (1576581) | more than 3 years ago | (#34411612)

It's full of three times the stars.

Re:My god . . . (1)

Monkeedude1212 (1560403) | more than 3 years ago | (#34411642)

How many library of congresses is that?

Re:My god . . . (1)

CosmeticLobotamy (155360) | more than 3 years ago | (#34411690)

Three times as many as before.

Re:My god . . . (1)

Nidi62 (1525137) | more than 3 years ago | (#34411762)

But is that 3 libraries of congress or a library for 3 congresses?

Re:My god . . . (2)

mug funky (910186) | more than 3 years ago | (#34411824)

congressmen can't read, duh.

Re:My god . . . (0)

Anonymous Coward | more than 3 years ago | (#34412086)

this one can: brazilian clown [washingtonpost.com]

Re:My god . . . (1)

mangu (126918) | more than 3 years ago | (#34412482)

congressmen can't read, duh.

this one can: brazilian clown

In this case at least, the jury is still out.

The article you quoted is full of inaccuracies. For one thing, "Tiririca" does not mean "Grumpy", that would be "Zangado" in Portuguese. "Tiririca"is the name of a common garden weed in Brazil.

More importantly, the judge mentioned there did not rule that Tiririca is able to read and write, he ruled that the candidate was not guilty of perjury just because he did not fill out himself the document stating that he's able to read and write.

Perhaps the Washington Post reporters aren't that much literate either...

Re:My god . . . (1)

dgatwood (11270) | more than 3 years ago | (#34411856)

No, spelled that way, it's more likely an adult book/movie rental house. Different kind of "congress".

Re:My god . . . (1)

Cow Jones (615566) | more than 3 years ago | (#34411994)

Even so, I'd say there are still billions and billions [youtube.com] of them.
"We have always been space travelers [youtube.com] ." - Carl Sagan

Re: My god . . . (1)

Black Parrot (19622) | more than 3 years ago | (#34413026)

It's full of three times the stars.

And that song about Van Gogh should have started "Starry, starry, starry, starry, starry, starry night".

More red dwarfs? (2)

Verteiron (224042) | more than 3 years ago | (#34411820)

The Chirpsithra will be thrilled.

Re:More red dwarfs? (1)

Low Ranked Craig (1327799) | more than 3 years ago | (#34411970)

But what percentage have one-face worlds?

Re:More red dwarfs? (1)

Pesticidal (1148911) | more than 3 years ago | (#34412580)

As long as Doug Naylor isn't involved, I'm looking forward to more episodes.

So, how many more ears do I need to cut off? (1)

PolygamousRanchKid (1290638) | more than 3 years ago | (#34411850)

Ah, Starry Night

( http://en.wikipedia.org/wiki/Starry_night [wikipedia.org] )

I only had two . . .

Re:So, how many more ears do I need to cut off? (1)

Surt (22457) | more than 3 years ago | (#34412006)

Sadly, this discovery shows just how incompetent a painter he was. There should have been three times as many swirlies. Or maybe he was just lazy. Anyway, I'm sure others will chalk it up to 'artistic license' rather than out their favorite painter as the fraud that he was.

I'd be suspicious of the numbers... (1)

Lord_of_the_nerf (895604) | more than 3 years ago | (#34411930)

...since these estimates came from Astronomers who previously worked at Goldman Sachs. Sub Prime real estate as it were.

The Starry Sky Just Got Starrier? (0)

Anonymous Coward | more than 3 years ago | (#34411938)

Or rather, humans just got less ignorant about the universe in which we reside? To say the sky got 'starrier' would imply that more stars are there than before...

Re:The Starry Sky Just Got Starrier? (2)

mangu (126918) | more than 3 years ago | (#34412542)

To say the sky got 'starrier' would imply that more stars are there than before...

No, it means there are more stars than we knew about before.

Oh my GOD! (2)

spongman (182339) | more than 3 years ago | (#34411966)

it's more full of stars!

Re:Oh my GOD! (1)

karlwilson (1124799) | more than 3 years ago | (#34412526)

WHAT DOES THIS MEEEAAANNN???

Re:Oh my GOD! (1)

GodfatherofSoul (174979) | more than 3 years ago | (#34412786)

First, a poster doesn't recognize a Spam skit parody, now a 2001: A Space Odyssey reference? This damned site has been overrun with jocks!

I dunno... (1)

tverbeek (457094) | more than 3 years ago | (#34412048)

{peers upward}

It looks the same to me.

YO !! DOOD !! YOU WANNA SCRORE SOME NUTMEG !! (0)

Anonymous Coward | more than 3 years ago | (#34412362)

It's the finest nutmeg you can get, dood !!

Nah, bananna peels are for lozers !! Nutmeg is dope, dood !!

hmm, still can't see them. (2)

Nyder (754090) | more than 3 years ago | (#34412438)

Nice, more stars.

can't wait to take my telescope out and look at them.

wait, what?

Accretion (1)

bdabautcb (1040566) | more than 3 years ago | (#34412626)

Mass questions aside, how do we know the age of these stars? The cores of rock planets in this solar system, especially Earth and Mars, resemble red dwarfs, and at a young age they were probably very similar. What about the planets of origins that are not so similar as ours, like Jupiter? There is some evidence that Jupiter, at an early stage of our solar system, was very similar to the Sun. By chance or what have you, two massive gas balls had a gravity fight, and the Sun won. The gas giants are more similar to the sun than they are to the interior planets and the outlying planetoids (as we apparently are now refering to neptune and pluto). If the collusion of gas and heavier element clouds create stars, and the collision of condensed gas and heavier element clouds create planets, and the gravitational eccentrices decide which cloud becomes a star and dominates its system, where the heavier, rockier objects collude, how do we know what designs a solar system? The point is, are these red dwarfs actually stars, or are they planetary objects orbiting in a still undefined system? Will one of them become a star like the sun, or will they collide and disperse into the galaxy as a mix of chemical elements? Is anything orbiting them, if so, is anything orbiting one of them at a more rapid rate than its partner? If Jupiter could have been a star, how do we not know that these phenomena are the birth of solar systems? I guess this news is not new to me, it just opens a lot of unanswered questions, and the proposition that Jupiter, at one point, may have been the center of the solar system, but remains a outlying planet of fusion reaction of gas and is not a star, begs more questions. Like are these dwarfs nebulous accumulations of gas that are in the process of forming solar systems? Will one of these red dwarfs become a sun and contain a system like ours? Or will many of them collide and become a blue giant and blast off there accumulative accretion disk, maybe become a gravitational phenomena? Will one red dwarf become a Jupiter while the other red dwarf is bombarded with outliers until it becomes a Sun and develops rocky planets like ours?

hmmm (1)

thatskinnyguy (1129515) | more than 3 years ago | (#34412886)

What does this mean for the mass of the Universe? Has the estimated quantity of dark matter been overestimated?

Have we made sure that... (1)

RevWaldo (1186281) | more than 3 years ago | (#34413000)

...the astronomer wasn't just hit on the head with a cartoonishly large wooden mallet?

.

E)4? (-1)

Anonymous Coward | more than 3 years ago | (#34413114)

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