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(The Australian)   "Dark Matter" permeates the universe. We can't really observe it, and even if we could, it's not like we have any idea what to do with it. But one man just became $300,000 richer because of it   (theaustralian.com.au) divider line 88
    More: Cool, dark matter, galaxy formation, National University of Ireland, University of Sydney, galaxies, telescopes, astronomy  
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6056 clicks; posted to Geek » on 31 Oct 2012 at 11:27 AM (2 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2012-10-31 02:38:55 PM  

jack21221: The original poster said that dark matter is undetectable. This is incorrect. Dark matter is detectable.


The effects of dark matter are detectable, yes.
 
2012-10-31 02:41:32 PM  

jack21221: The fact hypothesis is that dark matter exists.

 
2012-10-31 02:57:33 PM  

ThrobblefootSpectre: jack21221: The original poster said that dark matter is undetectable. This is incorrect. Dark matter is detectable.

The effects of dark matter are detectable, yes.


There are effects that have been detected. A theory of the existence of dark matter has been put forth to explain the effects. A physicist may come up with a more elegant explanation.
 
2012-10-31 03:03:35 PM  
I was taught that there are four generally accepted forces: The strong nuclear force, the electromagnetic force, the weak nuclear force, and the gravitational force. It is possible that there are further forces that are as yet unknown.
 
2012-10-31 03:05:32 PM  

Noah_Tall: An average person sees something that that can't be explained based on their knowledge. Rather than assuming that perhaps their knowledge is incorrect they give credit to an invisible force that fills the universe and can not be detected in any manner. They call it God and they are called superstitious.

A scientist sees something that can't be explained based on their knowledge. Rather than assuming that perhaps their knowledge is incorrect they give credit to an invisible force that fills the universe and can not be detected in any manner. They call it dark matter and they get a prize.


jack21221: This is completely incorrect, and you should be ashamed to post such nonsense.

1) Dark matter is not a force. It is a form of matter, and it is non-baryonic in nature. Beyond that, we don't know exactly what it is, but we do know enough to know it's matter and it isn't made of baryons.

2) There IS an invisible force that fills the universe, and that's called gravity. If you're incredulous that gravity exists, then I'm sorry about your brain injury.

3) Dark matter CAN be and HAS been detected through the gravity it exerts. Distributions of dark matter have been mapped in this galaxy and in others. It's detected by the invisible force listed above.


---------------------------------------------

Think of an invisible rock in the middle of a stream -- you can't see the rock but you can see the water going around the rock.

/or something like that
 
2012-10-31 03:20:42 PM  
I am the farthest thing from a scientist, but I have heard a hypothesis that one of the reasons gravity seems to be weaker than the other forces is that it 'bleeds' off in to other dimensions.

What if dark matter is simply the gravitational effect bleeding through to us from other dimensions?

'Parallel' universes would probably have similar dispersions of matter, so if there's a galaxy at point A in universe 1, there's a galaxy at the congruent point of universe 2.

Then you'd have a gravitational effect with no apparent cause.

I watch and read too much Science Fiction, I guess.
 
2012-10-31 03:37:14 PM  

PirateKing: I am the farthest thing from a scientist, but I have heard a hypothesis that one of the reasons gravity seems to be weaker than the other forces is that it 'bleeds' off in to other dimensions.

What if dark matter is simply the gravitational effect bleeding through to us from other dimensions?

'Parallel' universes would probably have similar dispersions of matter, so if there's a galaxy at point A in universe 1, there's a galaxy at the congruent point of universe 2.

Then you'd have a gravitational effect with no apparent cause.

I watch and read too much Science Fiction, I guess.


My guess is that gravity is part of the weak force. I base that on the idea that gravity is always pulling inwards, and never seems to gain more mass even though it has attracted mass. It never emits, and pulls.
 
2012-10-31 03:37:28 PM  

PirateKing: What if dark matter is simply the gravitational effect bleeding through to us from other dimensions?


It has been proposed before (e.g. here). However, these "braneworld" scenarios with extra dimensions are very, very speculative. It's much more likely that dark matter is some particle already postulated for other reasons, like the axion or neutralino.
 
2012-10-31 03:49:09 PM  

ThatBillmanGuy: Noah_Tall: An average person sees something that that can't be explained based on their knowledge. Rather than assuming that perhaps their knowledge is incorrect they give credit to an invisible force that fills the universe and can not be detected in any manner. They call it God and they are called superstitious.

A scientist sees something that can't be explained based on their knowledge. Rather than assuming that perhaps their knowledge is incorrect they give credit to an invisible force that fills the universe and can not be detected in any manner. They call it dark matter and they get a prize.

10/10

Sounded legit as a person who might actually think this argument will work on Fark.
Got a bunch of bites.

Congrats.


Indeed. It seems Bevets has evolved.

I wonder what he would think of that.

/still waiting for element zero
 
2012-10-31 04:03:22 PM  

ThrobblefootSpectre: TheOther: I guess the question is why isn't that internal space also expanding?

It is. But that space exists independently of the matter in or around it.


I know you aren't yanking me around, but that explanation sounds suspiciously like this one:

img522.imageshack.us 

Of course, I shouldn't have to ask questions like an 8 y/o kid, either.
 
2012-10-31 04:04:04 PM  

Ambitwistor: TheOther: But isn't most matter made up of empty space? I guess the question is why isn't that internal space also expanding?

Bound matter (atoms, solar systems, galaxies) doesn't expand in the same way that free, essentially non-interacting matter does. It resists the expansion of space. (Technically, it still does expand, but at a much, much slower rate.) See here and here.


Thanks!
 
2012-10-31 04:04:42 PM  

Tranquil Hegemony: TheOther: Another Stupid Science Question:

The universe is like an expanding loaf of raisin bread, with the distance between raisins increasing. Why aren't the raisins also expanding?

If the raisins are galaxies, than gravity keeps them from expanding. Galaxies in a cluster will generally stay together too, I think. Eventually (according to the Big Rip model) dark energy will become stronger than gravity and even galaxies and steller/planetary systems will fly apart. But that's a long, long time from now.


Thanks!
 
2012-10-31 05:38:38 PM  

Egoy3k: The scientist works under the assumption that their knowledge is incorrect and is constantly seeking to refine or replace it


I don't believe you. Prove it.
 
2012-10-31 05:57:44 PM  

ThatBillmanGuy: Noah_Tall: An average person sees something that that can't be explained based on their knowledge. Rather than assuming that perhaps their knowledge is incorrect they give credit to an invisible force that fills the universe and can not be detected in any manner. They call it God and they are called superstitious.

A scientist sees something that can't be explained based on their knowledge. Rather than assuming that perhaps their knowledge is incorrect they give credit to an invisible force that fills the universe and can not be detected in any manner. They call it dark matter and they get a prize.

10/10

Sounded legit as a person who might actually think this argument will work on Fark.
Got a bunch of bites.

Congrats.


Thank you. I had no idea how well this would work since I had to run to the dentist and just got back. I need to try trolling more often.
 
2012-10-31 06:17:19 PM  
I wrote a song about Dark Matter
Link
 
2012-10-31 06:23:25 PM  

Noah_Tall: Thank you. I had no idea how well this would work since I had to run to the dentist and just got back. I need to try trolling more often.


*blink*

Well played. IHL, I will HAND.
 
2012-10-31 07:07:01 PM  

TheOther: Professor Morgan Freeman?


Dr. Walter Bishop.
 
2012-10-31 07:57:31 PM  

ThrobblefootSpectre: hypothesis


That dark matter exists is an accepted fact in the astronomical community. The evidence for it is overwhelming. I'm glad you think you know better than the experts. I'm surprised you didn't say "it's just a theory" like the poster below you did.
 
2012-10-31 08:20:49 PM  
Yeah never mind the fact that scientists basically made up "dark matter" to explain away the inconsistencies between what Relativity says we should observe and what we actually observe. By all means, give the guy a prize instead of admitting that Einstein was probably wrong.

Verisimilitude biatch, do you speak it!
 
2012-10-31 08:50:47 PM  

Fano: Phlogiston is back!


aether?
 
2012-10-31 09:12:14 PM  

jack21221: That dark matter exists is an accepted fact in the astronomical community. The evidence for it is overwhelming. I'm glad you think you know better than the experts. I'm surprised you didn't say "it's just a theory" like the poster below you did.


No. Dark matter is not a fact. It is a hypothesis. A rather recent one that still needs a lot of observation and supporting evidence. There are several other competing hypotheses from respected cosmologists to explain the observations. Dark matter is by far the simplest, and so probably closer to the truth.

Please read at least something about the topic before saying this stuff again. Please?
Link

I can appreciate your enthusiasm for science, but when you go too far, you are actually doing the same thing religious people do. You are creating a religion out science by having what is known as faith. 

Go ask your science teacher tomorrow about this. He or she may be of some help.

Btw - Saying it is just a theory, is not an insult. :-)
 
2012-10-31 09:35:41 PM  

TheOther: Of course, I shouldn't have to ask questions like an 8 y/o kid, either.


No worries. The details of cosmological expansion are far from 8 year material. An expanding universe bugged the bejeebers out of Einstein himself. We are all asking questions. No one figured all this stuff out on their own, we all learned it piece by piece from having things patiently and repeatedly explained by someone else. All of us.
 
2012-10-31 09:41:22 PM  

Noah_Tall: Thank you. I had no idea how well this would work since I had to run to the dentist and just got back. I need to try trolling more often.


That was a hell of a piece of work, I have to say.
 
2012-10-31 10:42:59 PM  

ThrobblefootSpectre: No. Dark matter is not a fact. It is a hypothesis. A rather recent one that still needs a lot of observation and supporting evidence. There are several other competing hypotheses from respected cosmologists to explain the observations. Dark matter is by far the simplest, and so probably closer to the truth.

Please read at least something about the topic before saying this stuff again. Please?
Link

I can appreciate your enthusiasm for science, but when you go too far, you are actually doing the same thing religious people do. You are creating a religion out science by having what is known as faith. 

Go ask your science teacher tomorrow about this. He or she may be of some help.

Btw - Saying it is just a theory, is not an insult. :-)


I have a degree in this stuff you condescending asshole. I can recommend some textbooks for you. Carroll and Ostlie is the one we used. I also read Liddle.
 
2012-10-31 11:04:54 PM  

jack21221: I have a degree in this stuff you condescending asshole.


Interesting.

jack21221: I can recommend some textbooks for you.


And I would recommend any basic high school science text for you.
 
2012-10-31 11:15:31 PM  

ThrobblefootSpectre: jack21221: I have a degree in this stuff you condescending asshole.

Interesting.

jack21221: I can recommend some textbooks for you.

And I would recommend any basic high school science text for you.


Of course you would, because that's as far as you've gotten. You send me to wikipedia and high school texts, I send you to Carroll and Ostlie and Liddle. Liddle is a fairly easy read, and you can pick it up for 23 bucks on Amazon. I strongly recommend you read it.
 
2012-11-01 03:08:27 AM  

Tricky Chicken: This worked surprisingly well until they tried to predict the orbit of Mercury. Then Newtonian physics failed miserably.


I wouldn't say an error of 600 or so arc seconds per century in the argument of perihelion is a miserable failure.

In all honesty, until you're talking about 25-50% the speed of light Newtonian mechanics continues to give surprisingly accurate answers.

2words1finger: Yeah never mind the fact that scientists basically made up "dark matter" to explain away the inconsistencies between what Relativity says we should observe and what we actually observe. By all means, give the guy a prize instead of admitting that Einstein was probably wrong.

Verisimilitude biatch, do you speak it!


Of course Einstein was wrong, Relativity is a classical field theory where we require a quantum field theory. Now, the manner in which GR is "wrong" and the sense in which you mean "wrong" is similar to equating a 787 dreamliner with the Wright Brothers' flyer because they're both just airplanes.

Lest anyone walk away from your post with the wrong idea (that being that there are giant glaring problems in the Einstein field equations that Evil Scientists are working tirelessly to cover up), here's a dose of reality - In the domain of classical charged particles, the Einstein equations and Maxwell's equations provide the best description ever made of how the world behaves. In the laboratory, experiments have verified all manner of predictions sometimes to extremely high accuracy. On any scale smaller than the galactic, we have no evidence what so ever that would guide a replacement to these theories and a vast array of evidence indicating that things do, in fact, work as they predict to measurable accuracy. Meanwhile, on the galactic scale, the dark matter (which you seem to think we came up with one day while we were high or something) halos posited to exist provide exactly the gravitational field to explain galactic rotation curves, and given the existence of neutrinos a particle which doesn't even feel the weak force is hardly some giant leap of theoretical faith.

I'd also like to remark on how you apparently think that the successor to General Relativity will somehow be completely different from it. In reality, GR makes extremely accurate predictions over an enormous range of parameters, and anything proporting to replace it must reproduce all the correct predictions of GR within that range of parameters - just as GR must reproduce all the correct predictions of Newtonian mechanics in the appropriate limit.
 
2012-11-01 05:05:58 AM  
...and they still don't understand what light actually is.

/or isn't.
 
2012-11-01 06:08:40 AM  
I explained dark matter to a friend. He understood, even though I don't really understand it myself. Isn't that how religions get started?
 
2012-11-01 07:44:32 AM  

prjindigo: ...and they still don't understand what light actually is.

/or isn't.


The ignorance in this thread is astounding.
 
2012-11-01 09:58:28 AM  
I am also a denier of anthropomorphic universal expansion.
 
2012-11-01 11:05:02 PM  

erik-k: Tricky Chicken: This worked surprisingly well until they tried to predict the orbit of Mercury. Then Newtonian physics failed miserably.

I wouldn't say an error of 600 or so arc seconds per century in the argument of perihelion is a miserable failure.

In all honesty, until you're talking about 25-50% the speed of light Newtonian mechanics continues to give surprisingly accurate answers.

2words1finger: Yeah never mind the fact that scientists basically made up "dark matter" to explain away the inconsistencies between what Relativity says we should observe and what we actually observe. By all means, give the guy a prize instead of admitting that Einstein was probably wrong.

Verisimilitude biatch, do you speak it!

Of course Einstein was wrong, Relativity is a classical field theory where we require a quantum field theory. Now, the manner in which GR is "wrong" and the sense in which you mean "wrong" is similar to equating a 787 dreamliner with the Wright Brothers' flyer because they're both just airplanes.

Lest anyone walk away from your post with the wrong idea (that being that there are giant glaring problems in the Einstein field equations that Evil Scientists are working tirelessly to cover up), here's a dose of reality - In the domain of classical charged particles, the Einstein equations and Maxwell's equations provide the best description ever made of how the world behaves. In the laboratory, experiments have verified all manner of predictions sometimes to extremely high accuracy. On any scale smaller than the galactic, we have no evidence what so ever that would guide a replacement to these theories and a vast array of evidence indicating that things do, in fact, work as they predict to measurable accuracy. Meanwhile, on the galactic scale, the dark matter (which you seem to think we came up with one day while we were high or something) halos posited to exist provide exactly the gravitational field to explain galactic rotation curves, and given the existe ...


.....

Perhaps "wrong" is not the correct choice of word, which is why I made the snarky reference to verisimilitude. I mean, you said it right there with "On any scale smaller than the galactic...", and you left out the fact that it doesn't work when we scale things way way down as well. What we're left with is a theory that seems to be the most accurate only in the middle region of the scale. If the theory does not offer accurate predictions both up and down the scale, then it is worth questioning the true validity of the theory. Of course GR can predict a great many things to a relatively high degree of accuracy (no pun intended). My point is that as close as GR seems to be to the truth, it is not exactly on the mark, as evidenced by its irreconcilability with quantum mechanics and by things like the necessity for so-called "dark matter" and "dark energy" to explain our observations of cosmic expansion and our calculations of total mass in the universe. In light of these failings we could say that GR has a verisimilitude of .92 (just pulled that number off the top of my head, but it is close enough for this example). That leaves us .08 off-center from the truth Just imagine what information that 8% holds for us, information that we may never access, or at least will have to wait far too long for, unless more scientists start seriously questioning that Holy Grail of physics that Einstein came up with purportedly on his own while working as a patent clerk. The only problem with doing that is that GR has become so entrenched and accepted as the end-all be-all truth that questioning it is tantamount to professional suicide in academia.

Personally I'm particular to the work of Julian Barbour and his colleagues who have worked with him at College Farm in Banbury, England. Barbour can get away with throwing Einstein under the bus because he does not work within the academic systems, and in fact made his living for several decades as a translator. He is extrapolating on the ideas of Ernst Mach to create a unified model that so far appears to be just as accurate as GR AND is scaleable both down to the quantum level and up to the cosmic, and does not require any invisible mystery force/matter to explain our observations. As I understand it, one of the keys to Barbour's model is that any given body is measured not against a static background grid like GR's spacetime, but rather in relation to two or more other bodies. This property makes the model truly "relative", unlike Einstein's work.
 
2012-11-02 12:35:13 AM  

2words1finger: My point is that as close as GR seems to be to the truth, it is not exactly on the mark, as evidenced by its irreconcilability with quantum mechanics and by things like the necessity for so-called "dark matter" and "dark energy" to explain our observations of cosmic expansion and our calculations of total mass in the universe.


The existence of dark matter is not a failing of GR.
 
2012-11-02 02:07:14 AM  

jack21221: 2words1finger: My point is that as close as GR seems to be to the truth, it is not exactly on the mark, as evidenced by its irreconcilability with quantum mechanics and by things like the necessity for so-called "dark matter" and "dark energy" to explain our observations of cosmic expansion and our calculations of total mass in the universe.

The existence of dark matter is not a failing of GR.


Wow you need big on condescension and little of providing any refuting facts. That facts makes you less useful than those you belittle.
 
2012-11-02 03:01:11 AM  

jack21221: 2words1finger: My point is that as close as GR seems to be to the truth, it is not exactly on the mark, as evidenced by its irreconcilability with quantum mechanics and by things like the necessity for so-called "dark matter" and "dark energy" to explain our observations of cosmic expansion and our calculations of total mass in the universe.

The existence of dark matter is not a failing of GR.

.....

Why? Please explain to the class exactly why it is not a failing of GR. Please explain exactly why it is not a failing when cosmologists say "well based on our estimates of the total mass in the universe we should see "X", but our actual observations show us "Y", so based on GR there must be many, many times more mass in the universe than we can account for. I guess we'll have to just assume that there is some kind of undetectable particle out there that absolutely permeates the cosmos."

Are you going to try to use the age-old argument of virtual particles popping in and out of existence from quantum fluctuations? Sorry Charlie but as my daddy used to say, that dog don't hunt. It takes quite a bit of energy to virtualize any particle with significant mass, so unless you're very close to either the event horizon of a black hole or a star going nova, the only virtual particles you're going to see popping up from the foam are going to have a negligible mass, certainly not enough, even combined, to account for the assumed mass of dark matter.

So go ahead Chief, let's hear your argument.

You don't have one, do you?

Yeah, that's what I thought.... biatch.
 
2012-11-02 11:50:41 PM  

2words1finger: Why? Please explain to the class exactly why it is not a failing of GR. Please explain exactly why it is not a failing when cosmologists say "well based on our estimates of the total mass in the universe we should see "X", but our actual observations show us "Y", so based on GR there must be many, many times more mass in the universe than we can account for. I guess we'll have to just assume that there is some kind of undetectable particle out there that absolutely permeates the cosmos."


It's not just based on GR that baryonic matter doesn't account for the observed mass in the universe. It even fails on the Newtonian level. Proposals have been made, called MOND (MOdified Newtonian Dynamics), but that has fallen hard out of favor.

You clearly do not know anything about dark matter based on your descriptions. It does not "absolutely permeate the cosmos" as you say. It is clumped together in very specific configurations in galaxies and galactic clusters. Again, we can map it.

Also, as far as I have read, nobody has ever seriously proposed virtual particles as the source of dark matter. That straw man is a bit weird, to be honest. Currently, WIMPS (weakly interacting massive particles) are the number one hypothesis as to what dark matter actually is. They are hypothesized to exist in the most common extension of the Standard Model, called supersymmetry. The lightest SUSY particle makes an excellent candidate for dark matter. Another possibility are particles called axions. Axions were hypothesized as a solution to the strong CP problem, but it turns out they also make excellent dark matter candidates. There are a few other exotic hypotheses, but none of them involve virtual particles.

By the way, it's not even my job to present my argument to you. You're the one that's contradicting decades of established science. The burden of proof is on YOU to show your work. biatch.
 
2012-11-03 07:22:18 PM  

jack21221: That dark matter exists is an accepted fact in the astronomical community


How many "facts" does the astronomical community accept without being able to prove them? Lots? Sounds like good science to me, believing in things you can't see, measure, or replicate in the lab. You guys must have a lot of faith.
 
2012-11-03 08:46:04 PM  

untaken_name: How many "facts" does the astronomical community accept without being able to prove them? Lots?


Zero.
 
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