Invisible Dark Matter: Scientists have come up empty-handed.

Schmelzer said:
4. option.

First, the experiment was ok. Unfortunately, there is not "the" dark matter one can search for. What one can search for are for evidence of particular models for dark matter. If you have a model, you can look at what this model predicts, and, in this case, what possibilities would exist to detect dark matter if it would be of this particular form. Say, one possibility would be something similar to an atomic kernel but without electric charge. But with some strong interaction. This model would give some possibility to detect this type of dark matter, because this dark matter could hit some atomic kernels, which would lead to some, in principle visible, results. So, even if the experiment would have been ideal, this would be the death penalty only for this particular model of dark matter, not of dark matter in general.

Second, in some sense we can see dark matter already today. Roughly, we can measure the gravitational field $g_{mn}(x,t)$. This defines $G_{mn}(x,t)$. We can also measure, for all the visible matter, $T_{mn}(x,t)$. Their difference is dark matter. In this sense, "dark matter" can be interpreted as a name for something we can see, what we can measure.

Think about this as how such a thing develops. We start with the Einstein equations $G_{mn}(x,t)-T_{mn}(x,t)=0$. They are fine for the Solar system, for the perihelion of the Mercury, the deflection of light rays near the Sun, GPS and so on, fine - enough to see that GR is much better than Newtonian gravity.

The next step is to see that $G_{mn}(x,t)-T_{mn}(x,t)=0$ fails for galaxies. Once this was established, there are two solutions: a) GR is wrong, b) matter theory is wrong, there is some other matter we don't see. Above possibilities are a priori reasonable, one has to see what happens. But, once it has been established, once and forever, that $G_{mn}(x,t)-T_{mn}(x,t)\neq 0$, the job of the observers shifts. Their job is now to observe this difference $G_{mn}(x,t)-T_{mn}(x,t)$. Once at the moment this shift has happened variant (b) was more popular than (a), this difference $G_{mn}(x,t)-T_{mn}(x,t)$ as not been named "GR error" but "dark matter". One may object that this is a value-laden term which is prejudiced in favor of GR. Ok, but so what. So what we have now are observations of $G_{mn}(x,t)-T_{mn}(x,t)$, and this difference is named "dark matter" $T_{mn}^{dark}(x,t)$.

After this, one can simply try the following straightforward theories: 1.) The "dark matter" (whatever it is) behaves like massive particles with some mass, which does not interact with anything else, would behave. This is what is named "CDM" or "cold dark matter". It appears that it does not really matter how large these particles are, and what is their mass. What matters is that they have a mass, thus, do not have to fly around with speed of light but may exist in rest and with small velocities. What also matters is that they do not interact with usual matter. Once these two simple properties are fixed, the only thing which is unknown is essentially the density of dark matter. So, a pure CDM model adds one additional function to GR with visible matter only, namely the density of CDM. The equation for this type of dark matter is the same as for dust.

The distinguishable alternative is "hot dark matter", HDM, which is essentially the same, except that the dark matter is massless and therefore moves around with the speed of light. Once it (also) does, by construction, not interact with everything else, it essentially moves around freely. like light. This part of dark matter seems ignorable. Even if I have seen claims that some amount of it is necessary for explaining some globular clusters.

The point which matters is that the simple CDM model explains quite a lot of what is visible, if not all. Even if the accepted mainstream model is $\Lambda$CDM, which adds also Einstein's cosmological constant into the picture, there is Wiltshire's timescape cosmology which is pure CDM and yet seems viable.

So, the actual situation is that there is a model - CDM - which explains with sufficient accuracy almost everything, but, by construction, does not give us any idea other than observing $G_{mn}(x,t)-T_{mn}(x,t)$, to observe it. All what one actually can hope for is to invent models where this CDM is not exactly CDM, but in some way interacts with usual matter - and then to use this hypothetical interaction with usual matter to find it. These attempts up to now have failed. The CDM theory itself is unimpressed completely.
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You missed few option....I did not list them as they were not required for Paddoboy.


1. The quantum of baryonic matter improperly assessed.

2. The so called universal constant G being different up there.

3. MOND is actually right.

4. The maths with mass distribution of galaxy being non symmetrical may actually give such speed curves.

5. Improper speed measurements or interpretations. I am not doubting the capability, it is just the multitudes of issues involved.


See in case of Milky Way, our understanding has changed since Galaxy Speed distribution curves first obtained. So my vote can be for 1, 4 and 5.
 
timojin said:
Look pal I don't now how old you are. I have worked On surfaces analysis for over 10 years and I have seen and worked wit different electron microscopes, so don't try to impress me with your fancy stabbing words , and you can take your dolphin - sex to your home , which is vulgar ,
I am pro science , but I don't buy all kind of BS and then pad my self on the back and say I am a scientist .
Can you tell me what is your background ?
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The OP is the simple posting of an article.
Out of that, you've managed to find some way to troll the OP and try to bait an argument about anti-science. It's dishonest to post what you did and still claim to be pro-science.

I'm not trying to impress you, I'm trying to stay on-topic. Now, how about we talk about the findings of Dark Matter experiments.
 
The God said:
1. Experiment was bad.
2. DM does not exist. Fudge bluff is exposed.
3. Detector requires better precision.

Choose one or give a 4th option.
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4th option: Dark matter is not what we surmise it is. The experiment ruled out at least one hypothesis of what it is. That's progress.
 
The God said:
You have made around 10 odd posts in this thread, none talks about OP or science, you are just trolling.
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That is not actually what trolling means. Trolling is an intentional attempt to derail a conversation.

I have been trying to clarify the content of users' posts about the OP. That is on-topic (albeit indirectly).

BTW, also demonstrably wrong. See post 45.
 
Yes, the post #45, the first one on topic. But I was typing when you posted that.
Making 10 irrelevant posts, getting 10 counter replies, is certainly off tracking the thread. You please do not be a judge, just report and let the guys who are assigned the job handle.

BTW, also demonstrably wrong as none of your posts (barring #45) is an attempt to clarify the content.
 
The God said:
Yes, the post #45, the first one on topic. But I was typing when you posted that.
BTW, also demonstrably wrong as none of your posts (barring #45) is an attempt to clarify the content.
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Post 10 is on-topic, asking for clarification.
Actually post 3 is asking for clarification too.
It is on-topic to question the content of someone's response to the OP, (especially if it appears to be just off-loading bile). I am giving them a chance to show how their post is relevant.

Now, I've addressed this. Any further discusson can be taken offline so as NOT to distract from the topic.
 
Barring #45, all are irrelevant or annoying, a deliberate attempt to act funny. Infact #7 is puerile.

No more discussion with you on this, neither on line nor offline.
 
expletives deleted said:
But can't you see? The NON-normal DM is now no longer needed to explain things. The newly discovered Ordinary matter is sufficient to account for much of the anomalous motions etc; and the rest is just fine tuning of observed quantities and forces etc in play locally in the observed features/regions.
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This is pure fantasy.
 
While some are still are having problems with their knees and jerking, it's worth noting that as usual they are unable to support their stated ignorance with any reputable link.
DM still is certainly needed to explain what we observe and the effects that gravity has, not withstanding the next predicted [:rolleyes:] "fire and brimstone" evangelistic crusade directed in my direction. :)

Again as obviously those that are so tired up with their fire and brimstone preaching seems to have missed, with regards to "justified "appeals to authority" which of course will continue.....

https://www.google.com.au/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=appeals to authority
What is argument from authority?
The argument from authority (Latin: argumentum ad verecundiam) alsoappeal to authority, is a common argument form which can be fallacious, such as when an authority is cited on a topic outside their area of expertise, or when the authority cited is not a true expert.

What does it mean to appeal to a higher authority?
In informal reasoning, the appeal to authority is a form of argument attempting to establish a statistical syllogism. The appeal to authorityrelies on an argument of the form: A is an authority on a particular topic. A says something about that topic.

What is the fallacy of appeal to unqualified authority?
DEFINITION: The arguer appeals to an inappropriate or unqualified authority (expert) as the basis for accepting a conclusion. The viewpoint of such an individual is logically irrelevant. However, an appeal to a legitimate expert (i.e., Einstein in physics; eye-witness in court case) is a type of inductive argument.
 
The God said:
You have made around 10 odd posts in this thread, none talks about OP or science, you are just trolling.
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And you and expletive deleted have made many unsupported claims re mainstream cosmology in general, that totally defy the logic of the scientific method and peer review.
Your claims re DM is just one more to add to the nonsensical unsupported claims by both of you.
 
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DaveC426913 said:
Post 10 is on-topic, asking for clarification.
Actually post 3 is asking for clarification too.
It is on-topic to question the content of someone's response to the OP, (especially if it appears to be just off-loading bile). I am giving them a chance to show how their post is relevant.

Now, I've addressed this. Any further discusson can be taken offline so as NOT to distract from the topic.
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In actual fact the real "off topic" nonsense that the mods need to attend to, is the pseudoscience nonsense yourself and expletive deleted are flooding the science forums with:
We have the fringes for that nonsense, and which in time most of your own threads are removed to anyway.
 
paddoboy said:
And you and expletive deleted have made many unsupported claims re mainstream cosmology in general, that totally defy the logic of the scientific method and peer review.
Your claims re DM is just one more to add to the nonsensical unsupported claims by both of you.
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My claim regarding DM is nothing new. It is a fudge factor, that even you know.
 
The God said:
My claim regarding DM is nothing new. It is a fudge factor, that even you know.
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Your erroneous claim re DM is tilted obviously towards fabricated to invalidate cosmology once again, so that you can have that opening for your god of the gaps.
DM was initially a fudge factor...Findings and observational evidence since those days, has now seen it generally accepted by professional mainstream personel.
Same went with Einstein's CC, first obviously a fudge factor, but now not so certain.

Those findings obviously include the bullet cluster collision and gravitational lensing by DM.
 
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Just this last Friday, a local public lecture by a Prof. Elisabetta Barberio gave at the end what imo is so far the most convincing evidence favouring DM. Years of accumulated data showing consistent annual cyclic variations in scintillation counts at Gran Sasso DARMA underground particle detector facility. Pretty much everything within SM (standard model) is ruled out as explanation, leaving only some as yet unknown WIMP. A list of talks: https://people.roma2.infn.it/~dama/web/down.html
The first one: http://people.roma2.infn.it/~belli/belli_IDM2016.pdf
p2 outlines the idea. p7 provides the telling data. Numerous pages devoted to weeding out possible spurious sources. Looks good to me. Construction of a 'sister' facility in AU began this month. Hopefully will provide strong confirmation of Italian site's findings once up and running for a few years.
 
PhysBang:

PhysBang said:
This is pure fantasy.
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What is "fantasy"? Are you calling the current astronomers and their newest telescopes "fantasy merchants"?

Did you miss the last few years of (and ongoing) astronomical discoveries now slowly filtering into the literature and the theorists reviews of past theories which were formulated in total ignorance of what was really out there?

You must have missed my post where I pointed out how so much Ordinary 'stuff' is being found that was 'dark' before, and which when added up would explain much of the previously required 'dark' matter but now not needing to be Extra-Ordinary but Ordinary, as now increasingly found to be. If you missed it, here is the relevant bit:

expletives deleted said:
...recent astronomical discoveries of Ordinary Matter in space, which was previously 'Dark', now forms a great proportion of the 'Dark' component of the mass to explain the major component of the 'gravitational and motional anomalies' which had been assumed to be due to 'Extraordinary' Matter.

For example there are huge quantities of plasma and dust in nebulae and streams and filaments previously 'unseen'. Also thousands of 'now visible' low-brightness globular clusters, galaxies and galaxy clusters representing many times the 'previously visible' Ordinary Matter content in those regions involved.

And the infinite eternal matter and energy recycling universe can account for all the CMB and Baryon genesis and proportional elementary Hydrogen, Helium and other abundances observed in regions which may vary over recycling evolutionary epochs.
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So PhysBang, have you actually been keeping up with the science efforts and results in the relevant fields? It seems not. It might be better all round if you could catch up with what's going on in the real world instead of making uninformed trolling posts at me. Thankyou. Best.
 
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