Dark matter detected?

[GreyICE]

Uh yes. You do not know the basic facts.

• Dark matter is not undetectible - it can be detected because of its mass.
• A whole lot of evidence that relies on different theories and different techniques just demonstrates that the dark matter exists.

Ten pounds of theory ain't worth one ounce of fact.

I find the existence of something THREE TIMES the mass of the the OBSERVED UNIVERSE requires a bit more evidence than 'it makes our math good.'

You are wrong. Which apparently one of us understands...

Ignorance noted. Might want to think just a little the next time you link someone to wikipedia.

And, after checking your links, it boils down to math, math, and math. Based on our current theories.

Dark matter is a decent theory, but I don't find it passes the muster in terms of things we can state factually exist. And I don't see how you're stating otherwise.

 

[jsfisher]

I argue differently in this case because universally people who say 'dark matter can't be right' do not understand the basis of it. They need to come up with another hypothesis that is more elegant than adding some particles.

Then you would argue something that isn't science. If a given theory yields predictions that are provable wrong, then the theory is flawed. No alternate hypothesis required. Or would you allege that Michelson and Morley had no right challenging the theory of a luminiferous aether since they had no alternate hypothesis?

By the way, people who argue that "dark matter can't be right" and that's it are equally involved in non-science.

ETA: Such people have two options to put dark matter to bed. Either (a) prove a prediction false, or (b) provide a more attractive hypothesis. You seem to be saying Option (b) is the only option.

 

[Fnord]

I think we're all getting ahead of the confirmation phase. I mean, dark matter has not been repeatedly produced, right? And there yet exists no reliable method for churning out even a microgram of the stuff, so why keep harping on what is (at best) circumstantial 'evidence'?

I'm skeptical of any claims for the existence of dark matter, and will likely remain so until such a time as when enough of it is produced in a laboratory to determine its physical properties.

And I'm still suspicious of the researchers' motives for releasing any claims (expressed or implied) for the existance of the stuff when the competition for research money is so fierce. There's nothing wrong with overtly asking for more money, but to dangle a tidbit that only hints at potential success in front of potential donors ... well, it just seems a little ingenuous.

So just show me your god some dark matter, and I will believe.

 

[ben m]

And I'm still suspicious of the researchers' motives for releasing any claims (expressed or implied) for the existance of the stuff when the competition for research money is so fierce.

The funding agencies want you to publish this stuff. CDMS's job was to

(a) build a 5 kg low-background germanium detector
(b) run it for five years
(c) report the results

They're obligated to report the results of those five years of running. They're obliged whether it was zero events, or two events, or 1000 events which are obviously dark matter, or (as happens sometimes) "we tried to run this thing but ran into a noise problem". That's how it works: you do an experiment and you publish the results.

 

[Reality Check]

Ten pounds of theory ain't worth one ounce of fact.

The ounces of fact are:

1. Motion of galaxies in clusters.
2. Velocity dispersions of galaxies
3. Galaxy clusters and gravitational lensing
   Observations of colliding galaxy clusters.
4. Cosmic microwave background
5. Structure formation

I find the existence of something THREE TIMES the mass of the the OBSERVED UNIVERSE requires a bit more evidence than 'it makes our math good.'

Argument from personal incredulity.
The fact is that we measure that the universe is missing THREE TIMES the measured visible mass of the OBSERVED UNIVERSE.
The fact is that we measure that there is dark matter that makes up the descrepency.
If you don't like that then move to a universe that does not have dark matter in it !

Ignorance noted. Might want to think just a little the next time you link someone to wikipedia.

The you in "You are wrong. Which apparently one of us understands... " was you, GreyICE.

Occam's Razor

Occam's razor is not an embargo against the positing of any kind of entity, or a recommendation of the simplest theory come what may[32] (note that simplest theory is something like "only I exist" or "nothing exists").
The other things in question are the evidential support for the theory.[33] Therefore, according to the principle, a simpler but less correct theory should not be preferred over a more complex but more correct one. It is this fact which gives the lie to the common misinterpretation of Occam's Razor that "the simplest" one is usually the correct one.

There is the scientific theory that is backed up by several sources of evidence. There is 1 entity postulated in this theory (dark matter).

There is your theory which is basically that each of these several sources of evidence is flawed. I doubt that an unspecified flaw in evidence is an entity as needed for Occam's Razor. But let's ignore that.

Your theory requires an entity for each source of evidence. The observational evidence for dark matter comes from the following sources:

1. Motion of galaxies in clusters.
2. Velocity dispersions of galaxies
3. Galaxy clusters and gravitational lensing
   Observations of colliding galaxy clusters.
4. Cosmic microwave background
5. Structure formation

Your theory has postulated 5 entities. The scientific theory has postualted 1 entity. Thus Occam's Razor would favor dark matter.

Or you may be thinking that the theories underlying the observations are flawed. But there are at least 2 theories (GR and Newtonian mechanics). Thus Occam's Razor would favor dark matter.

And, after checking your links, it boils down to math, math, and math. Based on our current theories.

Yes it boils down to doing math, math, and math on the measurements of the universe using our current theories.
What theories should we be using? Past ones? Future ones?

Should we stop using math in all activities just because you do not like it ?

Dark matter is a decent theory, but I don't find it passes the muster in terms of things we can state factually exist. And I don't see how you're stating otherwise.

Dark matter is a placeholder for the stuff that explains a large set of observations. It is not a theory.
I am stating that there is overwhelming evidence for the existence of dark matter as above.
I am stating that the evidence for dark matter is as good as the evidence for other things, e.g. quarks. Quarks are just as invisible as dark matter. Their existence has to be established using math, math, and math based on our current theories.

 

[Fnord]

The funding agencies want you to publish this stuff. CDMS's job was to

(a) build a 5 kg low-background germanium detector
(b) run it for five years
(c) report the results

They're obligated to report the results of those five years of running. They're obliged whether it was zero events, or two events, or 1000 events which are obviously dark matter, or (as happens sometimes) "we tried to run this thing but ran into a noise problem". That's how it works: you do an experiment and you publish the results.

.
Okay, consider me facepalmed. I'd forgotten the 'Publish or Perish' rule of funded research.

Sorta like reporting every 30 minutes to the OOD, even though all you've seen the entire watch is darkness and fog, just so that you don't get put on report for dereliction of duty.

 

[ben m]

.
Okay, consider me facepalmed. I'd forgotten the 'Publish or Perish' rule of funded research.

Sorta like reporting every 30 minutes to the OOD, even though all you've seen the entire watch is darkness and fog, just so that you don't get put on report for dereliction of duty.

Sort of like that. Keep in mind, of course, that in physics a null result is often just as interesting as a discovery. The CHOOZ experiment, which reported in 1999 that it had not observed neutrino oscillations in a certain nuclear-reactor setup, remains one of the most important things we know about neutrino mixing. The dozens and dozens of papers from the Tevatron experiments, all reporting "We did not see any Higgs bosons doing X, we did not see any doing W, we did not see any doing V", are a large part of what guided the construction of the LHC; thanks to all of those "boring" publications, we didn't have to build a machine sensitive to V, W, and X (which were ruled out) and could focus on sensitivity to Y, Z, Z', etc.

You may think the CDMS paper boring because it didn't conclusively discover dark matter. I find it very interesting because it *did* conclusively rule out all of the things it didn't see. It's not clear whether the two events it saw make it more interesting or less interesting.

 

[MattusMaximus]

That is absolutely true. The mainstream needs to get over the idea that it's automatically right until proven wrong by something else that explains things exactly the same way better than it explains them. It's doesn't work that way.

Fixed that for you. As has been pointed out to you, it's about explaining things with a theory which is better in the sense that it is more explanative, unifying, parsimonious, etc than any others.

For now, from what we can tell, DM is it. But time will tell.

Btw, I just got done reading the original paper on this a couple of days ago, and I think the researchers did a bang up job of being quite up front about how they were NOT claiming to have directly detected DM. In fact, they practically bent over backwards making the case that they haven't detected it directly. Leave it to the media to screw up the science

 

[MattusMaximus]

I think we're all getting ahead of the confirmation phase. I mean, dark matter has not been repeatedly produced, right? And there yet exists no reliable method for churning out even a microgram of the stuff, so why keep harping on what is (at best) circumstantial 'evidence'?

I'm skeptical of any claims for the existence of dark matter, and will likely remain so until such a time as when enough of it is produced in a laboratory to determine its physical properties.

These are good points, and I - to a degree - share your skepticism of the DM theory. I have adopted it as a sort of tentative explanation for our observations, though what I am really waiting for is the direct detection of DM particles before I go buying in 100%. That is why I found this thread so interesting to begin with.

The big sticking point for me is, as I just mentioned, that from what I've seen the DM theory is the best one out there so far. Show me a better theory and I'll consider it.

So just show me your god some dark matter, and I will believe.

Nice. Pithy

 

[Dancing David]

Then you would argue something that isn't science. If a given theory yields predictions that are provable wrong, then the theory is flawed. No alternate hypothesis required. Or would you allege that Michelson and Morley had no right challenging the theory of a luminiferous aether since they had no alternate hypothesis?

By the way, people who argue that "dark matter can't be right" and that's it are equally involved in non-science.

ETA: Such people have two options to put dark matter to bed. Either (a) prove a prediction false, or (b) provide a more attractive hypothesis. You seem to be saying Option (b) is the only option.

Quite right! I agree.

Ockham's razor is a philosophical tool that is divorced from science. We could construct and find many actual scenarios where it is wrong.

ETA: I do not feel option B is the only option, however saying "I don't like the observation of the effects of all this unobserved mass." (a mischaracterization of GreyIce) is not option A. Just because someone doesn't like a consequence of an observation does not make option A.

 

[Dancing David]

I think we're all getting ahead of the confirmation phase. I mean, dark matter has not been repeatedly produced, right? And there yet exists no reliable method for churning out even a microgram of the stuff, so why keep harping on what is (at best) circumstantial 'evidence'?

I'm skeptical of any claims for the existence of dark matter, and will likely remain so until such a time as when enough of it is produced in a laboratory to determine its physical properties.

And I'm still suspicious of the researchers' motives for releasing any claims (expressed or implied) for the existance of the stuff when the competition for research money is so fierce. There's nothing wrong with overtly asking for more money, but to dangle a tidbit that only hints at potential success in front of potential donors ... well, it just seems a little ingenuous.

So just show me your god some dark matter, and I will believe.

Well, you do know that we have never and will never produce naked quarks in a collider?

The point is not about 'truth' it is about 'approximate models', if the dark matter theory (IE approximate model) matches the behavior of reality, make predictions about the behavior of reality and is usable. that is all that matters.

Such as here:
Obsevation of the Top Quark Production in P(overstrike)P Collisions

You will not ethat the charcteristics of the event are not teh actual observation of a nked quark. But the observation of events that match the predictions of the model of the top quark.


So the mischaracterization of science in your statement can be shown by subbing top quark for darkmatter.

So just show me your god some top quark, and I will believe.

This applies to electrons, magnetic fields and gravity as well.

All we have is approximate models of the behavior of reality. they are just that words and thoughts we use to describe reality.

Gravity is just a label, it is just a thoery, it is not something you can hold in your hand, so too for top quarks and dark matter.