Dark Matter - The Search Continues

a reply to: ErosA433

very incorrect ??
what ? the mathematical recipes ??
don't think they're wrong... they are actually very correct describing so called gravity in two body systems

test particles ?? you mean imaginary one ?? sure you mean this...

you know me in the mean time so you probably know there is coming more...

every mathematical formula is basically just a recipe how to do things... like counting in this case

so how do you apply a recipe like this??
F = -GMm/r2

listen... take the number someone gives you and multiply it by the mass of the one body you are calculating in the system ( however this mass was calculated/measured (not so easy) ) and multiply it by the other mass and then divide it by the power of two (2) of the measured distance between them.

right ??
NO ?
sure right !

sure you can do an average sum integration of all the output numbers for every single two ( 2) mass interaction.
but this does not make it right.

look...
the mass of an galaxy is all the stars INSIDE of this galaxy. period!!

therefore taking any single star that makes the mass of the "whole" galaxy and applying the recipe to it as if they are just 2 unrelated masses that are separated by a distance is nonsense.. any integration of nonsense is still nonsense.
( the mass of the particular star as 'm' and the mass of the galaxy as 'M' )

I think there is one thing you may not see...
'M' and 'm' are two ( 2 ) different things.
but if 'm' is a part of 'M' they are NOT!!
the recipe does not work..
how can you do not see it ??

So once again you have no idea what it is you are talking about and under estimating the level of study that has gone into it.

please finish the sentence...

I do have no idea ?, I just have presented one to you !
you may say, you do not accept my idea, but saying I have no idea is just not true


BTW:
I do understand that there is a lot of afford put into the "implementation" of dark mater into the model that just do not work, I really do, but I also think the world is going on, we should let go the old prejudices/premises and look for the "real thing"

a reply to: KrzYma


I always said that to juxtapose galaxies with solar systems as a constant may be problematic

a reply to: ErosA433

Looking for the spirit molecule lol . Good luck with that.

is this what ATS is now? Free form trolling? We should probably just have the Science and Tech forum renamed, Fantasy and bullpap. Ill keep looking for the Spirit Molecule... LOL... and contribute lots more to society then snippy mysticism ever did.

Nothing to add? Then please just let what ever unfinished thought flow onto the keyboard, lets get more noise to swamp out these signals.


There is not really a problematic treatment of gravity, the galaxies rotate and work perfectly at their cores, its on the outer most edges. I find it interesting that people have problems with understanding that.

I also find it quite interesting how you KrzYma are telling me things that are exactly proven to be incorrect as a solution, you have no clue at all what you are saying. You can show, through mathematical rigour that what i described in one sentence is actually more sound than what you are saying.

You are sort of doubling up statements that contradict each other. First saying that you can't add it up and then saying you should, and then saying if you do its wrong and right. Sorry maybe i just don't understand your point, but, to be honest I don't actually think you understand what you wrote or are trying to say.

Do you honestly think that after a century of trying to figure out these issues that, no one ever thought "oh wait we are not accounting for things correctly, let me just look at Newtonian mechanics a bit more and oh look its a silly mistake." You seem to think that the whole of the scientific community are comprised of morons who can't do simple math. And yet, you prove time and time again that you yourself don't actually understand simple concepts.

See what you are actually doing is the following

F = G integral Mdm/dr where this says the force experienced by mass dm is the integral of everything on the inside. Its also provable that IF the system is approximately symmetric, the mass on the outside results in a net ZERO force addition.

BUT hey, we never thought of that right and we don't know how to do math.

a reply to: ErosA433
Dark matter and galaxy rotation curves are a complicated topic. I also find that KrzYma's attempted explanations are somewhat incoherent and in some cases, this case included, are also self contradictory. The contradiction is of course is that the laws of gravity are not being applied correctly, then he attempts to try to explain how to apply them correctly but I don't think he's ever done a calculation.

This is not to support what Kryzma is saying because it doesn't say the same thing even though it says non-baryonic dark matter is not needed to explain the rotation curves of galaxies:

The Calculations of Gravity Fields and Rotation Curves of Whirlpool Galaxies and Dark Material

The gravity fields and rotation curves of whirlpool galaxies with thin disc distribution of material are calculated numerically. It is proved that the gravity field of mass thin disc distribution is greatly different from that of spherically symmetrical distribution. As long as the Newtonian theory of gravity is used strictly, by the proper mass distributions of thin discs, the flat rotation curves of whirlpool galaxies can be explained well. The rotating curve of the Milky Galaxy is obtained which coincides with practical observation. In this way, it is unnecessary for us to suppose the existence of additional dark material in the illuminant discs of whirlpool galaxy again. Meanwhile, in the space outside the illuminant disc, the quantity of dark material needed to maintain the flatness of rotation curves is greatly decreased. By considering the observation fact that the quantity of non-luminous baryon material is 3~10 times more than luminous material, we can explain the flatness of rotation curves of whirlpool galaxies well without the hypotheses of non-baryon dark material.

These physicists obviously know math better than Kryzma, though I didn't study their calculations in detail. One point the paper tries to make is that one model for dark matter distribution which says it's spherically distributed in disk galaxies has problems with matching galaxy rotation curves, and maybe they could have a point there. I can't confirm that and haven't studied it in detail but if dark matter and visible matter are gravitationally clumping together, wouldn't it make more sense if they did so in similar shapes (disk versus disk) instead of differing shapes (disk versus sphere)?

But I still have problems with the paper by Xiaochun et al where like Kryzma, it's not clear to me that the authors understand the observational data leading to the non-baryonic dark matter hypothesis since so much of this observational data is not considered or discussed. I'm paraphrasing a bit but the paper by Mei Xiaochun, Xu Kuan, Yu Ping seems to say if there's more baryonic dark matter in the disk of disk galaxies, the math will work out to match the rotation curves, but how can they either not know about and or not address all the searches for such baryonic dark matter, like gravitational microlensing experiments which place constraints on the abundance of MACHOs?

It's like Xiaochun et al are trying to propose a solution without really understanding all the problems, and problems is plural because our models don't exist in isolation. It's not just galaxy rotation curves which suggest non-baryonic dark matter, it's also gravitational lensing observations and big bang nucleosynthesis models for how much baryonic matter is needed to produce the observed amounts of deuterium and helium:

The Big Bang Nucleosynthesis theory predicts that roughly 25% the mass of the Universe consists of Helium. It also predicts about 0.01% deuterium, and even smaller quantities of lithium. The important point is that the prediction depends critically on the density of baryons (ie neutrons and protons) at the time of nucleosynthesis. Furthermore, one value of this baryon density can explain all the abundances at once. In terms of the present day critical density of matter, the required density of baryons is a few percent (the exact value depends on the assumed value of the Hubble constant). This relatively low value means that not all of the dark matter can be baryonic, ie we are forced to consider more exotic particle candidates.

So that and gravitational lensing are other lines of evidence besides galaxy rotation curves which suggest the existence of something like non-baryonic dark matter. Even if someone can recalculate galaxy rotation curves, that doesn't solve the other discrepancies and when you have multiple lines of evidence saying all those discrepancies might be solved by the existence of "WIMPS", then it makes sense to at least search for the as yet unseen "WIMPS".

WIMPs are not the only possible candidate, in fact dark matter could be more than one thing. Certainly some dark matter is baryonic, but there are other candidates like primordial black holes which could be low enough mass to not show up in gravitational microlensing experiments (though somewhat oddly, astronomers also call black holes baryonic, even if they don't really have any baryons). If Hawking's theory of black holes is correct those should show up at their end of life by emitting a specific type of radiation, and observations are not showing a lot of such signatures. You posted a chart with a lot of other candidates too, some of which I understood and some which I didn't.

As far as I can tell, people like KrzYma and perhaps Xiaochun et al and others who say they have the answer, don't fully understand the questions.

a reply to: Arbitrageur

thats more patent and well put than i could do at the time of my rant Arbitrageur so many thanks for that. I think you are right, the thing of solving one single issue or proposing that one thing is actually ok sort of doesn't actually solve the question being asked since the question and evidence is much larger.

Its similar with Mond, and the Bullet cluster, it is just not clear how such a model can predict or explain its existence or the behaviour we observe. MACHOs and the undercounting of substellar objects is another one too

a reply to: ErosA433

I have a question about the background sources. From the article:




There are 6 terms in the equation which represent the total number of regions of interest. Is it possible to segregate these regions such that the detector could deal with only one at a time? Or are they artifacts that cannot be separated out individually? As the events occur and are analyzed, does the algorithm differentiate between the events and report unique results for each event? How would you know if the ROI's are interacting with each other producing all sorts of anomalies?

The PMTs are calibrated before the LAr is inserted into the chamber. Then calibrated every day it appears - if one of the regions produces an anomaly, how would you detect it? Is there some baseline or standard?

Just thinking like a bench chemist, if I was looking for some artifact that is otherwise undetectable, why would I start with a mixed sample?

As you can see, I know zip about particle physics, but I'm curious about the methods.

This paper (reference #10 from the first paper posted by Eros) describes the design and construction of the DEAP - 3600 dark matter detector. The article answered some questions which I had about the methods employed for the experiment.

Design and construction of the DEAP-3600 dark matter detector

A.AmaudruzlM.BaldwinjM.BatygovdB.BeltranaC.E.BinaaD.BishoplJ.BonattfG.BoormaniM.G.BoulayfcB.BroermanfT.BromwichhJ.F.BuenoaP.M.BurghardtkA.ButcheriB.Ca ifS.ChanlM.ChenfR.Chouinarda…J.Zielinskil

www.sciencedirect.com...

In case you didn't find the answer already (sorry had a long day yesterday) The Region of interest is actually an energy region rather than a part of the detector.

It is postulated that the energy of a WIMP like event would be fairly low recoil energy. In liquid argon we also differentiate between nuclear recoils and electromagnetic events via a pulse shape timing property of pure liquid argon (A quirk of its chemistry shall we say) So the Region of interest is defined as an area in Energy vs Fraction of Prompt photons (Pulse shape of an event).

The detector is actually spatial separated into regions based upon if events are coming from outside the detector, inside the core or 'fiducial' volume of the argon, or outside the fiducial volume. I think for that detector its basically an inner sphere, there was some discussion of a different shape cut but i think for that analysis its a spherical cut around the inner 1 Tonne core of liquid.

Each of these backgrounds are simulated based upon direct assay of the materials used to build the detector, so knowing the concentrations of things like Uranium and Thorium but also stuff like potassium, gives us a good way to predict the radioactivity in the detector and where the events are most likely to occur. So that is where the fiducial cut comes in, surfaces are often the origin of radioactivity and such many of such events occur or are primarily detected on the outer edges of the detector. These as such, are easy to cut out.

The backgrounds are separated into these different classes because ultimately they are easily identified in distributions as they look significantly different from oneanother based upon event energy, timing distribution, event topology. The simulations are performed, the background sources based upon measurements of detector materials are cross referenced with clean sample regions in the detector and we look at all the events and predict what the backgrounds should be, in counts and in energy.

The best example of this is the Gamma spectrum of the experiment.

a reply to: ErosA433

Sorry maybe i just don't understand your point, but, to be honest I don't actually think you understand what you wrote or are trying to say.

your first statement, that you don't understand my point is clear... no doubt bout it.
the second statement, is what I hear from you all the time... still does not make it valid

again... F = -GMm/r2
What I'm saying is, and this is that you seemingly can't wrap your head around is, that there is no 'm', there is just 'M', so the equation is not calculable, especially not for v = sqrt(Gm/r) as this equation comes from the first, the 2 mass equation.

a reply to: Arbitrageur

These physicists obviously know math better than Kryzma..

this is quite an interesting statement...
so you say something like 1+1*1 can be understand differently by different people ??
maybe it also can be understand differently every time a single person is looking at it ??
quite interesting... make me think if you doubt your understanding of math??

...though I didn't study their calculations in detail.

and if you had, I assume it would make it right, ...or wrong, depending on your point of view...

and now... all those troubles come from the ignorance making G responsible for all that we can observe out there..
that's really funny, considering the fact that there is no working explanation for G or M at all, just quests...

a reply to: ErosA433

I have a quick question about the term "WIMP acceptance" - page 13 under Methodology it states: "........... and fiducial cuts were tuned on the background models to satisfy the targets while maintaining the highest achievable WIMP acceptance" - also page 23 VIII WIMP SEARCH ANALYSIS.
Does this mean that when the upper and lower limits have been established and all the cuts are made, that the output (if there is one) can be characterized as a WIMP? I'm thinking in terms of isolation and characterization of something - anything for that matter. In other words, if the target produced an event after accounting for every possible interference, scatter , impurity - which turns out to be a huge challenge, you could assume that whatever was detected in the WIMP ROI was in fact a WIMP.

Apparently, nothing was found in the WIMP ROI. Will they repeat the experiment or look to make modifications in the methodology? The complexity and fine tuning of the experiment design is amazing.

a reply to: Phantom423

Your thinking there is more or less correct.

Basically what they did was to look at the events in the detector and isolated a couple of locations that are problematic for the background model, namely the surfaces and the neck region of the detector.

The surfaces because surface features at the micro-scale produce energy 'leakage' into the energy region of interest (ROI)
-> What i mean by this is that if a radioactive decay in the liquid argon should deposit energy and give you 40,000 photons in the detector actually doesn't go into the liquid argon but instead sort of skims the surface, you don't produce all that 40,000, but far less and such surface events can leak down into the energy ROI, to get around this, you only accept events from the inner 1 tonne volume of argon (out of about 3.5 of the detector)
-> The neck of the detector is where the cooling is provided, it has higher surface area and a few detector components that basically mean it is a background liability. There are also no photosensors directly below the neck or looking directly at the neck. This makes events occuring at the neck itself hard to characterize. Thus the region around the neck was not considered for analysis. 'Neck events' can be characterised via timing and a few other topological effects and such anything that matches the criteria as a 'neck event' was removed.

They basically tried to get a detector sample that was free of background and set the limit then based upon the exposure time and mass of the target.



The experiment is still on going at SNOLAB, they actually have a dataset that is roughly 2-3 times that of the paper, so the search continues so to speak. It is unclear what the future of the experiment is though it will likely be decommissioned in another year or so. There was a design flaw that meant it couldnt reach its full design target mass of 3600kg liquid argon, there is some possibility of fixing that, however many of the people who built the equipment to purify the argon have since moved on. The expertise isn't lost, it is all well documented but a restart of that system isn't simply turning it on, some of the equipment would require lots of recommissioning and debugging after being sat idle for 2-3 years.

originally posted by: KrzYma
a reply to: ErosA433
again... F = -GMm/r2
What I'm saying is, and this is that you seemingly can't wrap your head around is, that there is no 'm', there is just 'M', so the equation is not calculable, especially not for v = sqrt(Gm/r) as this equation comes from the first, the 2 mass equation.

Simply put, this statement is incorrect. You can, if you study any physics and astronomy, look at a star, you can then, based upon its distance, observed luminosity and colour spectrum (stellar class) give a fairly good prediction of its mass.

Newton and Kepler both gave different treatments of orbital mechanics and when we take examples in which we can infact 'weigh' objects due to observed movement in pairs or groups we can double check we get our mass range correct. We also know the mass of the sun as a test reference, and the masses of the planets also as test references to make sure we at least get the G constant correct.

So when it comes to galaxies, you can, with a reasonable certainty, look at the luminosity and apparent colour of a star field and calculate its mass. With a nearby object such as Andromeda you can take that a step further and look at stars and gas clouds.

To make a blanket statement that "We cant measure anything!" is to be ignorant of the entire field of astronomy and physics for a few hundred years. Calibration of ur distance scale is being updated constantly based upon measurements of objects and so called standard candles... objects which should give almost exactly the same amounts of light when they occur to within great accuracy. So your statement comes quite clearly ignorant of the reality and what the state of play is.

If you want to state "You guys don't know Newtons force equation!" you have to prove your statement with a good amount of backup... all i see from you is dismissal with zero evidence... as per usual for your posts.

originally posted by: ErosA433
is this what ATS is now? Free form trolling?

To the extent we can collectively prevent it, hopefully not.

It is best to remember that those who use bluster to attempt to bolster their positions do so from a position of insecurity. If they had confidence in their beliefs, they wouldn't feel the need to discourage discussion of them.

But more to the point, ad hominem attacks and related forms of personal commentary, direct or indirect, violate the AboveTopSecret.com Terms And Conditions Of Use and posts containing them are subject to removal. If you or anyone should encounter such posts, please alert us and we'll look into the matter.

Going forward, speaking to everyone interested in participating, and no one in particular, let's all please do our best to stay focused on the topic, minimize snark and bear in mind that good people can disagree on just about anything.

If anyone should have any questions or comments regarding this post, please don't hesitate to send me a private message and I'll be happy to address them to the best of my ability. Please DO NOT respond to this post in this thread, since we're trying to stay on topic.

As always, thanks to everyone willing to keep things civil.

That's what makes it all worthwhile.

a reply to: ErosA433

Simply put, this statement is incorrect. You can, if you study any physics and astronomy, look at a star, you can then, based upon its distance, observed luminosity and colour spectrum (stellar class) give a fairly good prediction of its mass. Newton and Kepler both gave different treatments of orbital mechanics and when we take examples in which we can infact 'weigh' objects due to observed movement in pairs or groups we can double check we get our mass range correct. We also know the mass of the sun as a test reference, and the masses of the planets also as test references to make sure we at least get the G constant correct. So when it comes to galaxies, you can, with a reasonable certainty, look at the luminosity and apparent colour of a star field and calculate its mass. With a nearby object such as Andromeda you can take that a step further and look at stars and gas clouds. To make a blanket statement that "We cant measure anything!" is to be ignorant of the entire field of astronomy and physics for a few hundred years. Calibration of ur distance scale is being updated constantly based upon measurements of objects and so called standard candles... objects which should give almost exactly the same amounts of light when they occur to within great accuracy. So your statement comes quite clearly ignorant of the reality and what the state of play is. If you want to state "You guys don't know Newtons force equation!" you have to prove your statement with a good amount of backup... all i see from you is dismissal with zero evidence... as per usual for your posts.

what ... ... are you talking about ???

I just said the mass of every single star in a galaxy should be counted as the mass of the whole galaxy, therefore there is no 2 masses separated by a distance, and therefore you can not use the F = -GMm/r2 and calculate velocity with the v = sqrt(Gm/r)


on the other hand, of course if you have clearly separated masses like one galaxy and another galaxy ( however they masses are calculated, measuring is not possible at all ) you are dealing with 2 masses and the math can be applied.

I think you are confused...

wow you literally just didn't read or try to understand what i said... what i said is exactly that

When you calculate the orbital velocity of your stars in a galaxy you account for the mass on the inside of its orbit using what you know about the stars on the inside. Astronomy and Physics is way more careful at looking at this than you want to accept or even fathom and yet you continually accuse thousands of people of being supremely ignorant.

Its rather an interesting state to be.

*sigh* similar to the previous thread in which i said it, im just going to pretty much stop replying to you specifically as this is clearly going nowhere. You may comment as much as you like, you have been given answers, you clearly do not want to understand out of a desire to feel like you are superior or in some way on top of some grand conspiracy.

a reply to: ErosA433
If you are interested in a scientific explanation of the posts in this thread, I suggest studying the research by David Dunning and Justin Kruger. That explains a lot.

One of the case studies they looked at was McArthur Wheeler who tried to make himself a form of "dark matter" so to speak. He thought he could rob banks without being caught if he made himself invisible to the security cameras, and the way he tried to do that was by covering himself in lemon juice.

I'll bet that the scientific community hasn't even considered the hypothesis that the dark matter can't be seen because of being covered with lemon juice, since I don't recall seeing that option listed on your chart of the possible explanations for dark matter.

a reply to: ErosA433

When you calculate the orbital velocity of your stars in a galaxy you account for the mass on the inside of its orbit using what you know about the stars on the inside.

The basic argument of KrzYma seems to be that since stars are inside the galaxy the masses overlap and you cannot calculate the orbital velocity using standard equations. It's obviously a flawed argument, as you say we can account the mass inside and outside of the orbit. More importantly though, for the stars on the edge of a galaxy, virtually all the mass of the galaxy is inside the stars orbit, and it's the stars on the edge which show us most predominantly the effect of dark matter.

a reply to: ChaoticOrder

Yep, exactly this.

The question of mass measurements, orbits and light spectra are topics that go under a lot of scrutiny and research in astronomy. To basically say "its wrong" with little more than "You dont understand your equations" doesn't quite cut the mustard as a rebuttal.

I was going to post something about Roche surfaces and how when you are a relatively small distance away from a close orbiting binary, the gravitational potential very approximately becomes the same as a singular object. It is almost perfect at long distances. I didn't discuss it because i didnt think it was that useful. It was mostly that, while a star would have orbital peturbances caused by the stars in its local vicinity, the stars on the inside of its orbit, as far as it observes, act like a sigular mass. The distribution of this mass isn't spherical, granted, but it isn't wrong to use the equations assuming good radial symmetry.

a reply to: ChaoticOrder

we can account the mass inside and outside of the orbit. More importantly though, for the stars on the edge of a galaxy, virtually all the mass of the galaxy is inside the stars orbit, and it's the stars on the edge which show us most predominantly the effect of dark matter.

you're just as naive as the other ones...

look at this graph


the dot line is the calculated speed from v = sqrt(Gm/r)
that comes from F = -GMm/r2

in this equation, 'm' is not inside 'M',
and if you calculate it as such... it is at r0 or less in r axis

if you're telling me, the "whole" mass inside the galaxy, is one that is excluding the mass of the star on the edge of the galaxy... well... than you can imaginary calculate anything you want..

what you ignorants do not understand is the fact that as for example if you look at the sun, the corona is definitely outside the suns mass... like the outer stars in the galaxy... or is it not ??
now, it moves with the same speed as the sun.

it is one mass.. period!
same for the outer stars in the galaxy, all the stars is the mass of the galaxy, even that one you want to take out !

you can not take one mass out of it and apply the newtention mathematics of two separated masses to it ( F = -GMm/r2 ) and calculate the wishful rotational speed as if those are 2 separated masses..


and YES !!
I am saying that all "super brains" phd dreamers are wrong!

think for yourself !