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The Starry Sky Just Got Starrier
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."
dark matter much?
It's full of three times the stars.
I read TFA and all I got was this lousy cookie
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?
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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.
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They don't determine the mass of a galaxy by counting stars.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
> 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 )
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
I believe this 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.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
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.
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.
The Kruger Dunning explains most post on
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.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
From Popular Science 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.
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.
Sig Battery depleted. Reverting to safe mode.
Important to you, maybe...
You are welcome on my lawn.
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.
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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
Learn something new.
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.
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The big bang is just hand-waving at this point in time.
Hand-waving, one of the most successfully predictive theories 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.
The enemies of Democracy are
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...
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
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.