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- Junkyarddawg, on 10/12/2007, -0/+18My understanding is that dark matter doesn't interact with electromagnetic forces (e.g. light) so you can't see it. It only interacts with gravity.
- existent, on 10/12/2007, -6/+23Isn't that a little too convenient?
- baxtermaddux, on 10/12/2007, -2/+16What about Nibbler's Poop?
- danieldrehmer, on 10/12/2007, -3/+17@existent
Since it interacts with gravity, it could be tested and also falsified. Thus, it is a genuine scientific hypothesis.
This year, by taking the picture of a collision between two galaxies, astronomers found a very relevant evidence of dark matter, by measuring the gravitational effect of what was believed to be it. This event could be predicted and explained by dark matter and the current gravitational theory. However, if someone comes out with a simpler and more elegant explanation, every reasonable person should question the standard model. - Alphabet, on 10/12/2007, -0/+10Nasa already has direct proof of dark matter. It got on the front page of digg too.
http://digg.com/space/NASA_Discovers_Dark_Matter
More indepth, with video too.
http://chandra.harvard.edu/photo/2006/1e0657/ - pjleonhardt, on 10/12/2007, -0/+9we fully accept the _concept_ of a god.. just not the _existence_ of one.
The same way I fully accept that concept of Dark Matter, because right now it is our best guess. For me however, it reminds me too much of when they explained how light traveled with the magical 'ether'. We probably have it the gravitation equations still wrong. The same way Einstein fixed Newton's Equations to account for objects at high speeds, someone will correct Einstein's equations for things with extremely high masses... - capiCrimm, on 10/12/2007, -0/+8regardless, it's better to refine a rough model like "ether" then to have no model at all.
- magicjava, on 10/12/2007, -6/+14The thing I've always wondered about dark mater is that if galaxies are filled with this stuff, why do we not see it here on Earth? We are, after all, in a galaxy.
- webcrumb, on 10/12/2007, -5/+13There was such a thing as the "ether" that surrounded everything in space and kept it in place... until we found out that there in fact wasn't such a thing.
Making up a catch-all is just an easy way to explain something. - danieldrehmer, on 10/12/2007, -0/+6That's because these theories CAN be tested. Theories are open ideas to be discussed, which opposes dogma and something that no one can put in question because its immaterial, omnipotent, and/or exists in a reality outside this universe.
No one can see dark matter, and even thou it is something that can be tested and disproved. - shimavak, on 10/12/2007, -0/+4An interesting theory Grillmiester, and one that is fully testible, and (lucky for you) has been. It doesn't work because we see this apparent change of the fundamental constant G (6.67*10^-11 m^3 / kg^2 s) as being visible in many galaxies, universally, independant of redshift (z). This means, if we've got our other theories right, that we're pretty much stuck with having either G change as the distance between gravitational objects increases, or that we have not observed all of the mass that really is present in these large systems.
It is interesting to note that this deviation of the constant scales with the size of the system, so both possibilities work. Unfortunately for the theory of G changing, we really like to have constant constants (go figure), and we also have some fairly good evidence otherwise that this is really due to excess unobserved mass.
But hey, why worry about the dark matter? It is, after all, only ~23% of the universe. The real fun thing to worry about is the dark energy! That accounts for roughly 76% of the "stuff" in the universe. This leaves about 1% for all of the observed universe. These values are (as another poster mentions) _highly_ constrained, and not subject to more than a little wiggle room (~1%).
As an aside, for those unaware, dark matter makes gravity appear to be stronger than what we would expect from the luminosity curves, whereas dark energy does the opposite, it makes things appear to be less bound than what we expect. Read all about it and have fun! After all, this is nothing compared to the problems with supersymmetry
(which might be able to explain some of these dark things, if only it weren't ~60 orders of magnitude off...) - zephc, on 10/12/2007, -1/+5The hidden mass comes from all those turtles. They go a long way down, you know!
In all seriousness, I've always liked the the explanation of the missing mass caused by Type III+ civilizations* using a lot of mass to create galactic-size super-structures. However, a natural explanation seems far more plausible.
* http://en.wikipedia.org/wiki/Kardashev_scale - tulpe, on 10/12/2007, -3/+7a "concept of a god" raises more questions than it solves.. get it?
- radekg, on 10/12/2007, -1/+5"But for 70 years, cosmologists have never observed dark matter..."
This is not true.
http://home.slac.stanford.edu/pressreleases/2006/20060821.htm
http://chandra.harvard.edu/press/06_releases/press_082106.html
http://chandra.harvard.edu/photo/2006/1e0657/ - hackwrench, on 10/12/2007, -1/+4Some helpful Wikipedia articles:
http://en.wikipedia.org/wiki/Tensor
http://en.wikipedia.org/wiki/Vector
http://en.wikipedia.org/wiki/Scalar
http://en.wikipedia.org/wiki/TeVeS - carve, on 10/12/2007, -0/+3It is still only a theory. We need to have Intelligent Falling taught in schools along side the theory of gravity...
http://www.theonion.com/content/node/39512
RAmen - Jugalator, on 10/12/2007, -1/+4Hehe, in the case of this theory, it then has to explain the effects from gravitational lensing, often assumed to empirical signs of dark matter. Example picture here: http://en.wikipedia.org/wiki/Image:Abell.lensing.arp.750pix.jpg
- inactive, on 10/12/2007, -0/+3Dark matter has already been observed, this theory is useless without explaining that. http://home.slac.stanford.edu/pressreleases/2006/20060821.htm
- Junkyarddawg, on 10/12/2007, -0/+3OK, to you guys who like me have read this article... hands up everyone who understood it.
Could you perhaps explain what their theory was to me, an interested amateur? Because I didn't understand a word. - existent, on 10/12/2007, -6/+9One fits inside their belief systems, one doesn't. No difference otherwise.
- Democritus2, on 10/12/2007, -1/+4Skeletal then you should read most of the other comments that offer some insight and some links. No, instead you post under the one nonsensical statement. Of course he is right, dark matter is pasta sauce.
- kyledavis, on 10/12/2007, -0/+3"The theory...allows for fast growth of density perturbations arising from small inhomogeneities during recombination."
*slaps forehead* Oh, it's so OBVIOUS now! :-) - Marthinus, on 10/12/2007, -0/+2Also science is the human voyage to better understanding. With our limited knowledge we theorize about things we observe and then we test those theories, some hold others not. For the ones that don't we create new theories and so the cycle continues until we have better understanding.
It will always be like that. That is what makes science interesting, but to me it also makes science not to be the Alpha and Omega of it all, catch 22 really. - b00le, on 10/12/2007, -0/+2It's one thing to accept a concept as a possibility, quite another to believe in something in the complete absence of evidence. I personally 'feel' that the dark matter theory is wrong, but I won't give any weight to that feeling because I don't have any data to back it up. The theory can and will be tested against observation, and even the strongest believers will be ready to change their minds if the theory fails such tests. It's called rationality. Believers in God can't be reasoned out of their belief because they have no rational basis for it in the first place. They just have to stop believing. (It's easy...)
- zadadka, on 10/12/2007, -0/+2Kinda hard to have faith in the implied superiority of someone with the name SkeletaLlama.....
(ps, you have an "l" missing) - archlich, on 10/12/2007, -0/+2 "Observed dark matter" means that we see the effects of something. We call it dark matter because we really don't know what the hell is going on.
- inactive, on 10/12/2007, -4/+5Pastafarians already know where the universe came from....flying spaghetti monster!
Think of dark matter like....pasta sauce. - archlich, on 10/12/2007, -0/+1moving along...
- hackwrench, on 10/12/2007, -0/+1This article has helped a little with that last bit though...
http://en.wikipedia.org/wiki/Solar_nebula - yahoofrom, on 10/12/2007, -0/+1The dark matter turns out to be the... ether...
[joke] - d0b33, on 10/12/2007, -0/+1Firstly... I don't believe nor disbelief anything, you could call me agnostic I guess...
but I based my question on this :
"Bestsellers by Richard Dawkins and Sam Harris have denounced the evils of religion and proclaimed that science has proven that there is no God"
http://www.thegodtheory.com/
I do denounce religion, but I don't think that science has proven anything about God yet, If it did I would be an atheist.
(when I refer God, I don't mean in a religious sense but in a creator/planner of the universe)
Sorry for going off topic guys, but thanks anyway - dudad, on 10/12/2007, -0/+1The equations that we have for gravity are wrong for some reason on very large scales.. no doubt about it. But the question is whether it's the equations themselves that are wrong or because we can't yet really detect dark energy. Hopefully we can detect them and do find them which we simply need either more powerful accelerators or just more time (gamma ray astronomy takes time). If after a few decades we don't find more evidence (either for or for the contrary) then it will probably called bunk.
Now gravity waves.. I'd argue that they don't exist over dark matter and energy. - webcrumb, on 10/12/2007, -2/+3Yes, but you are then working on proving the existence of ether, rather than looking for the actual answer... if your model doesn't work likely your model is wrong, rather than you have missed something you can't measure...
- archlich, on 10/12/2007, -1/+2Basically it says that gravity increases as two objects become farther apart, sort of like the nuclear force.
- hackwrench, on 10/12/2007, -0/+1An article in the sidebar
http://www.physorg.com/news82910712.html
Planck instruments ready for integration
says:
This pattern is influenced by the amount of normal matter, dark matter and dark energy that fills the Universe. So using Planck's maps, astronomers will be able to place the most stringent limits yet on the quantities of these three universal components.
So, what will that be detecting if dark matter doesn't exist? - inactive, on 10/12/2007, -0/+1sorry for not sharing some's enthusiasm, but don't you think that the last 10 years we are bombarded with theory after theory on cosmology in a form of "catchy titles"? at least, if there was some noticeable effort to educate people on that stuff rather than stay on the "we found how the universe works! woohoo! yeah!" factor..
- Neiby, on 10/12/2007, -0/+1Interestingly, there is a new ether-based model out there that has an different take on gravity that does not require dark matter. Since it is ether-based, it obviously isn't going to get a lot of time in the mainstream, but there are more and more Ph.D-level physicists seriously taking a look at this.
http://www.quantumaetherdynamics.com/aether.html
I can't find the page where they specifically deal with gravity, though. I'll keep looking to see if I can find it. I haven't looked at this stuff in many months. - Neiby, on 10/12/2007, -0/+1Oops...actually, I may have been wrong. The Aether Physics Model may actually assume that dark matter does exist. Ignore my comment for the time being.
- hackwrench, on 10/12/2007, -0/+1"a "concept of a god" raises more questions than it solves.. get it?"
I don't. The concept of a god questions raised/solved ratio has always been better than alternative explanations for the things I put the concept of a god to explain. Usually the alternative explanation is randomness, but I've yet to hear the explanation for why the orbits of all the planets of this solar system are practically along the same plane. - SteveDeGroof, on 10/12/2007, -0/+1"why do we not see it here on Earth?"
To paraphrase Holly: Well, the thing about dark matter, its main distinguishing feature, is it’s dark. And the thing about space, the color of space, yer basic space color, is its black. So, how're ye supposed to see it? - inactive, on 10/12/2007, -0/+1"the feature of Bekenstein’s theory that Dodelson and Liguori focus on most is that the theory—unlike standard general relativity—allows for fast growth of density perturbations arising from small inhomogeneities during recombination."
Uh uh. Yes. Yes. Now I see. Now it all makes sense. - schroduggity, on 10/12/2007, -4/+4plasma cosmology does a good job of describing the universe without dark matter. even the recent colliding galaxy observation.
http://en.wikipedia.org/wiki/Plasma_cosmology
the article is disputed, but by definition so is theoretical physics. i'm no physicist I'm just throwin it out there for people who've never heard of it. - Jugalator, on 10/12/2007, -2/+2"It interests me that some atheists accept theories that have yet to be proven, yet won't accept the concept of a God...?"
What's so interesting about that?
Going from the dark matter theory to the concept of an abstract creator of the universe is quite far fetched, don't you think?
Let's rephrase this question to be less controversial by not mixing up personal beliefs with scientific theories, but still trying to remain essentially the same otherwise: If a person doesn't believe in the big bang theory, but that there was another scientific explanation for the formation of the universe; would you still believe it was "interesting" if this person didn't believe in the dark matter theory?
It seems the "interesting" part here lies merely in the controversy in your question itself, and I guess that's indicative of a sarcastic troll post. - Junkyarddawg, on 10/12/2007, -0/+0@archlich: OK, so over small distances (e.g. within solar system distances) gravity must decrease with the square of the distance, then at longer distances decrease at some lower pace than the square of the distance. Yeah, that would explain things like galaxies or superclusters without dark matter. Am I correct in thinking this theory is impossible to verify/test?
- toonevdb, on 10/12/2007, -0/+0Almost every theory has been proven wrong or inaccurate over the course of history.
For me science is just a handy framework to predict a certain outcome, it doesn't neccessarely mean nature is that way.
My best guess is nature and everything is build up of one thing which has trillions of variations, we just haven't reached the fundamental building block. - grillmiester, on 10/12/2007, -2/+1My lame theory is that gravity changes with time.
My understanding is that dark matter was first dreamed up to explain the velocities of spiral galaxies. The arms spun much faster than the amount of visible matter says they should. To make the numbers come out right you can add more mass or choose a different g.
If the light coming from the galaxies took millions of years to reach us. They fabric of space-time they occupied at that time could be very different from what we experience today.
- SEN5241, on 10/12/2007, -1/+0Dark matter seems like a bogus invention to fit the universe to our model of understanding (kind of like the cosmological constant).
I'll be glad when dark matter goes the way of the ether (which went the way of the dodo). - SkeletaLlama, on 10/12/2007, -6/+4I came to the comment section to see what Digg thought of this article and instead I'm reading stupid comments about pasta sauce. I should have known better.
- avasol, on 10/12/2007, -6/+0Look. I think most Americans are polarized dumbasses. I believe in science, and I believe in God (but I don't think God has the mind of a 5-year old and thus I don't believe in Creationism). I also believe in reincarnation (incidentally what Jesus actually taught back in the days), and a global subconsciousness (religious AND psychology, wow), as well as many parts of Gaia theory (mix it up). I also like sex, beer, drugs, and although heterosexual to the max I'm definitely not against gays. In fact, I'm not against anyone except people who try to put labels on stuff because that's the only way they can explain it. Oh and I have an X-box 360 AND a Wii and I will also purchase a PS3. See how to avoid conflict in that area? Well? Or let's just say that the only thing worse than an idiot is an intolerant *****. If we can't have peaceful co-existence and a multitude of options open to us, we as a race are ***** up. "My father's kingdom has many hallways" - J-man, the historical dude with some pretty fascinating stuff to say.
- d0b33, on 10/12/2007, -12/+2Interesting....
off topic/
It interests me that some atheists accept theories that have yet to be proven, yet won't accept the concept of a God...?
/off topic
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