How do we know dark matter exists?

March 13, 2015 by Fraser Cain, Universe Today
A massive cluster of yellowish galaxies, seemingly caught in a red and blue spider web of eerily distorted background galaxies, makes for a spellbinding picture from the new Advanced Camera for Surveys aboard NASA's Hubble Space Telescope. To make this unprecedented image of the cosmos, Hubble peered straight through the center of one of the most massive galaxy clusters known, called Abell 1689. The gravity of the cluster's trillion stars — plus dark matter — acts as a 2-million-light-year-wide lens in space. This gravitational lens bends and magnifies the light of the galaxies located far behind it. Some of the faintest objects in the picture are probably over 13 billion light-years away (redshift value 6). Strong gravitational lensing as observed by the Hubble Space Telescope in Abell 1689 indicates the presence of dark matter. Credit: NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI),G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

Dark matter can't be seen or detected by any of our instruments, so how do we know it really exists?

Imagine the Universe was a pie, and you were going to slice it up into tasty portions corresponding to what proportions are what. The largest portion of the pie, 68% would go to dark energy, that mysterious force accelerating the expansion of the Universe. 27% would go to , the mysterious matter that surrounds galaxies and only interacts through gravity. A mere 5% of this pie would go to regular normal matter, the stuff that stars, planets, gas, dust, and humans are made out of.

Dark matter has been given this name because it doesn't seem to interact with regular matter in any way. It doesn't collide with it, or absorb energy from it. We can't see it or detect it with any of our instruments. We only know it's there because we can see the effect of its gravity.

Now, you might be saying, if we don't know what this thing is, and we can't detect it. How do we know it's actually there? Isn't it probably not there, like dragons? How do we know dark matter actually exists, when we have no idea what it actually is?

Oh, it's there. In fact, pretty much all we know is that it does exist. Dark matter was first theorized back in the 1930s by Fritz Zwicky to account for the movement of galaxy clusters, but the modern calculations were made by Vera Rubin in the 1960s and 70s. She calculated that galaxies were spinning more quickly than they should. So quickly that they should tear themselves apart like a merry-go-round ejecting children.

Rubin imagined that every galaxy was stuck inside a vast halo of dark matter that supplied the gravity to hold the galaxy together. But there was no way to actually detect this stuff, so astronomers proposed other models. Maybe gravity doesn't work the way we think it does at vast distances.

But in the last few years, astronomers have gotten better and better at detecting dark matter, purely though the effect of its gravity on the path that light takes as it crosses the Universe. As light travels through a region of dark matter, its path gets distorted by gravity. Instead of taking a straight line, the light is bent back and forth depending on how much dark matter is passes through.

And here's the amazing part. Astronomers can then map out regions of dark matter in the sky just by looking at the distortions in the light, and then working backwards to figure out how much intervening dark matter would need to be there to cause it.

These techniques have become so sophisticated that astronomers have discovered unusual situations where galaxies and their dark matter have gotten stripped away from each other. Or dark matter galaxies which don't have enough gas to form stars. They're just giant blobs of dark matter. Astronomers even use dark matter as gravitational lenses to study more distant objects. They have no idea what dark matter is, but they can still use it as a telescope.

They've never captured a dark matter particle, and haven't studied them in the lab. One of the Large Hadron Collider's next tasks will be to try and generate particles that match the characteristics of dark matter as we understand it. Even if the LHC doesn't actually create dark matter, it will help narrow down the current theories, hopefully helping physicists focus in on the true nature of this mystery.

This is how science works. Someone notices something unusual, and then people propose theories to explain it. The theory that best matches reality is considered correct. We live in a modern world, where so many scientific theories have already been proven for hundreds of years: germs, gravity, evolution, etc. But with dark matter, you're alive at a time when this is a mystery. And if we're lucky, we'll see it solved within our lifetime. Or maybe there's no dark matter after all, and we're about to learn something totally new about our Universe. Science, it's all up to you.

Explore further: Research pair suggests dark matter could create halos of light around galaxies

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Stevepidge
1.5 / 5 (23) Mar 13, 2015
What a monumental waste of intelligence and resources. Theories based on the principles forged by Newton, who had no idea that Electricity and plasma existed should be relegated to the 17th century. Good luck with your Maths, no matter how beautiful, like Ptolemy's it all will turn out to be rubbish. Just another validation that mankind is as fallible as ever.
antialias_physorg
4.8 / 5 (20) Mar 13, 2015
Good luck with your Maths, no matter how beautiful, like Ptolemy's it all will turn out to be rubbish.

So in your opinion we should never do anything or use any kind of theory because they will eventually be supplanted? That seems nonsensical.

Of course will every theory that we currently have be supplanted by something better. Do you honestly think that there is even one scientist who thinks otherwise?
That doesn't mean we shouldn't use the ones we currently have to the best of our abilities. Because only if you push something until it breaks do you find the new stuff.

Just sitting on our thumbs and saying "the current theories aren't perfect so let's ignore them" isn't going to get us anywhere
reset
1.8 / 5 (11) Mar 13, 2015
So in your opinion we should never do anything or use any kind of theory because they will eventually be supplanted? That seems nonsensical.


In order for a gravity based theory of motion to work, scientists had to add 4X more gravity to the universe...then claim the theory still works.
That seems nonsensical as well.

That doesn't mean we shouldn't use the ones we currently have to the best of our abilities. Because only if you push something until it breaks do you find the new stuff.


It does when it's that far off. Add to that the nature of particles in space is no longer based on their mass, but their charge.

Just sitting on our thumbs and saying "the current theories aren't perfect so let's ignore them" isn't going to get us anywhere


Neither is adding variables that don't exist in order to keep the current theories afloat.


Scroofinator
2.6 / 5 (13) Mar 13, 2015
How do we know dark matter exists?

We don't.
antigoracle
1.3 / 5 (15) Mar 13, 2015
How do we know dark matter exists.
Because these scientists have it in the brain.
NorEastern
3.3 / 5 (12) Mar 13, 2015
Dark matter and dark energy are not the only explanations for the observed facts. They are just the simplest.

Remarkably ignorant comments so far.
Dethe
1 / 5 (9) Mar 13, 2015
Some astronomical pictures illustrate the presence of dark matter more clearly than others. For example this picture imagines the collision of galaxies, the one of which on the left is surrounded with thick coat of dark matter, so it does separate the another one at distance. So if you take a look at it, you will say: there must exist some spacer cloud or field between galaxies!

Otherwise the question, whether the dark matter exist brings a deeper questions about nature of existence - that is to say, the dark matter rather exists as a field of virtual particles, rather than the real ones. It represents a transition between particles and field concepts.
Dethe
1 / 5 (10) Mar 13, 2015
The water surface analogy of space-time makes the nature of this transition rather obvious and easy to understand: at the water surface we recognize both well defined waves, both well defined vortices (analogy of particles with center of mass) - but the absolute majority of artifacts there is formed with turbulent mixture of both. In this sense the dark matter doesn't only represent a violation of general relativity (which is the way, in which it was originally observed), but also the violation of wave-particle duality of classical Copenhagen formulation of quantum mechanics. This formulation essentially says, we can observe wave or particle aspects of reality, but not both at the same moment (principle of complementarity). Well, it's evident, this complementarity can be still broken, albeit in quite subtle inconspicuous way.
Dethe
1.3 / 5 (9) Mar 13, 2015
The conceptual problem of contemporary physics with dark matter is, it does recognize only massless fields around well defined massive pinpoint particles - not the existence of massive field as such. This problem is both result of belief in validity of schematic formal theories, both the consequence of insufficient technology for dark matter detection. We must admit, that the mainstream physics improves its understanding of dark matter (after sixty years of its complete ignorance) rather fast and it converges to the concept of unparticle field, but the searches for dark matter are still influenced with reductionist dichotomy of existing theories. I'm pretty sure, that the dark matter is mostly formed just with artifacts, the existence of which mainstream physics denies for the whole century (scalar waves of Nikola Tesla).
vic1248
1 / 5 (6) Mar 13, 2015
What if the universe is here and expanding because there is a force outside of it and not subject to its realm, time and Laws of Nature/Physics acting upon it? I believe the key lies in the "Origin" of life and matter.

The "Dark Matter Hypothesis" is on the brink of obsoleteness. The Scientific Community is taking a final stab at encountering WIMPs —Weakly Interacting Massive Particles— which are hypothesized to make up Dark Matter. If scientists do not encounter WIMPs this time around, they will move on to other explanations.

Regarding proven science, I don't believe 'evolution' has ever been proven! Also, to this day, science does not know what gravity is nor the source of it. All what empirical science can do is observe the effects of gravity and calculate its rate of acceleration.
liquidspacetime
1 / 5 (9) Mar 13, 2015
There is evidence of dark matter every time a double slit experiment is performed; it's what waves.
Dark matter has mass. Dark matter physically occupies three dimensional space. Dark matter is physically displaced by the particles of matter which exist in it and move through it.

The Milky Way's halo is not a clump of dark matter anchored to the Milky Way. The Milky Way is moving through and displacing the dark matter.

The Milky Way's halo is the state of displacement of the dark matter.

The Milky Way's halo is the deformation of spacetime.

What is referred to geometrically as the deformation of spacetime physically exists in nature as the state of displacement of the dark matter.

A moving particle has an associated dark matter displacement wave. In a double slit experiment the particle travels through a single slit and the associated wave in the dark matter passes through both.
Kron
1 / 5 (2) Mar 14, 2015
Dethe, Scalar field (zero spin) permeates space, has been shown with discovery of Higgs boson at CERN. The Higgs boson is the only 'elementary' scalar particle. The Higgs field is a scalar field. All 'visible' matter is composed of fermions leptons and gluons (spin, electric charge, color charge). DM has no electric charge, we know cause we cannot see it. DM most likely is not in form of hadrons (no color charge), not all of it anyways. Neutrinos cannot be the ONLY DM particles either (ruled out). Lack of WIMP detection thus far discounts DM weak force properties (as for now). So in all likelihood your proposal is correct. DM particles are most likely scalar in nature, like Higgs boson. IF I were to garner a guess on the subject I'd say that Dark Matter is the Higgs field. Both Dark matter and Higgs field are hypothetical however.
Moebius
2.3 / 5 (6) Mar 14, 2015
We know it's there because of its effect on things we don't completely understand either? That's an amazing leap of knowledge.
Benni
1 / 5 (8) Mar 14, 2015
It's all about the "computer modeling" mostly of Spirals. What astronomers often do to make presentations of DM is to airbrush a darkened sort of halo into an actual photo of a galaxy, this becomes is what is termed a "simulation". The link below explains the modeling features of generating simulated DM halos. When you're looking at what you think are pictures of an astronomical object, always look under the picture for the term "Simulation", then you know it's essentially an air brushed picture with digitized highlights inserted to create features for things only presumed to exist.

http://arxiv.org/...46v2.pdf
Dethe
2.2 / 5 (6) Mar 14, 2015
We know it's there because of its effect on things we don't completely understand either
We know dark matter is here, because we can observe it. It doesn't imply, that we know that the dark matter is composed of material particles.
I were to garner a guess on the subject I'd say that Dark Matter is the Higgs field
These things aren't completely different each other, but they do apply to completely different distance scales and the Higgs field is supposed to be an omnipresent field, whereas the dark matter is localized to presence of observable matter.
chardo137
1 / 5 (1) Mar 14, 2015
There exists a formal scientific paper with the title: "Is dark matter an illusion created by the gravitational polarization of the quantum vacuum?" It is worth reading. http://arxiv.org/...47v2.pdf
Benni
1 / 5 (5) Mar 14, 2015
We know dark matter is here, because we can observe it


Would I ever like to have your eyeballs. In spite of the plethora of material conjecturing that we can't "observe it", you can. Be so kind as to describe what you saw?
Dethe
1 / 5 (6) Mar 14, 2015
Some astronomical pictures illustrate the presence of dark matter more clearly than others. For example this picture images the collision of galaxies, the one of which on the left is surrounded with thick coat of dark matter, so it does separate the another one at distance. So if you take a look at it, you will say: there must exist some spacer cloud or field between galaxies!

The separating effect dark matter can be observed with naked eye, if you know just a bit about astrophysics. The core of most of galaxies (including Milky Way) is formed with yellowish older mature stars of high metallicity, despite the concentration of interstellar gas is maximal there. With compare to it, the galactic arms have blue color, which means, they're formed with hot shortliving and fresh stars. The extreme example of this paradox is the Hoags object.
Dethe
1 / 5 (5) Mar 14, 2015
Do you see this paradox? The stars don't form & grow just at the place, where they have most of interstellar dust for their growth. Why it doesn't happen there? Well, the dark matter at the center acts as a foam or jelly separating the stars and particles of interstellar gas.
Benni
1 / 5 (7) Mar 14, 2015
There exists a formal scientific paper with the title: "Is dark matter an illusion created by the gravitational polarization of the quantum vacuum?"


In summation, MOND is a modified version of Newtonian gravity referring to the "inverse square law". The inverse square law applies not only to gravity but also electromagnetism.

The thing that mystifies astrophysicists is why Elliptical galaxies rotate at a rate that comports with Newtonian gravity "inverse square law". Ellipticals rotate at about 2 km/sec as compared to Spirals at about 200 km/sec. The important caveat here is the fact the largest Spirals are way smaller in mass than the largest Ellipticals which are the galaxy types that create gravity lensing features, something Spirals do not do. DM hypothesis is only is never applied to Elliptical rotation.

We know from observation that the typical Spiral does not create lensing because their weaker gravity fields compared to Ellipticals do not contain enough mass.
Dethe
1 / 5 (5) Mar 14, 2015
IMO the elliptical galaxies are completely different beasts than these spiral ones and they have much longer history, which probably extends the visible universe timespan. They're also differently structured in hyperdimensional way, being composed from myriads of stellar groups with no free stars between them. They're as different from spiral galaxies as the hadrons differ from leptons.
Benni
1 / 5 (6) Mar 14, 2015
IMO the elliptical galaxies are completely different beasts than these spiral ones and they have much longer history, which probably extends the visible universe timespan. They're also differently structured in hyperdimensional way, being composed from myriads of stellar groups with no free stars between them.

For sure Ellipticals are different, they also contain 60-70% of the stars in the universe & are commonly 50 times the size of MW.

So isn't it interesting that Ellipticals do not need a DM component to explain their rotation at 2 km/s, but by some sort of magic Spirals at 200 km/s supposedly have so much DM that we're unable to see 95% of the stuff of which Spirals are composed? Doing the math this would make Spirals 20 times more massive than what we observe, probably enough to create gravitational lensing, yet we don't observe them doing this. Why?

Dethe
2 / 5 (4) Mar 14, 2015
Spiral galaxies produce lensing too, just in smaller extent (10 - 20%). IMO they have dark matter present in form of thin ring at the galactic plane and central bulge, i.e. their DM lensing is constrained to areas, where it cannot be observed easily due to its nontrasparency..
Benni
1 / 5 (6) Mar 14, 2015
Spiral galaxies produce lensing too, just in http://iopscience...ext.html (10 - 20%). IMO they have dark matter present in form of thin ring at the galactic plane and central bulge, i.e. their DM lensing is constrained to areas, where it cannot be observed easily due to its nontrasparency..


You'd better go back & read that link again, the 10-20% is an extrapolated statistic, not a real number. The miniscule number of Spirals observed to create lensing is observed only with those which have extraordinary large central bulge, and then the lensing effect by those Spirals is very minimal, nothing like what is created by Ellipticals.
IMP-9
5 / 5 (7) Mar 14, 2015
Elliptical galaxies rotate at a rate that comports with Newtonian gravity "inverse square law".


You've already been corrected on this but you still act ignorant. Bulk rotation=/= orbital speed. Not all galaxies are supported by rotation, many are dispersion rotated. Most elipticals however are rotationally supported, and that rotation velocity shoots up to hundreds of kilometers per second. Dark matter models agree with this because rotation speed isn't orbital speed, your claim elipticals are somehow completely different cannot explain this.

http://arxiv.org/abs/0908.2995

Dark matter has been applied to ellipticals, you do need it if you actually measure the orbital velocity and don't stick to your straw man argument.
Benni
1 / 5 (9) Mar 15, 2015
Elliptical galaxies rotate at a rate that comports with Newtonian gravity "inverse square law".


You've already been corrected on this but you still act ignorant
No, just the opposite, I can read rotation curves you conveniently ignore just because you want DM distributed equally everywhere even where it is not needed.
Most elipticals however are rotationally supported
And DM is not needed to explain 2 km/s at the outer rim of Ellipticals.

Dark matter has been applied to ellipticals, you do need it if you actually measure the orbital velocity and don't stick to your straw man argument.
The DM model as applied to Spirals completely falls apart when it is applied to Ellipticals. Ellipticals do not need the DM gravity model to explain the rotation rate of 2km/s at the outermost rim of their disks, Newtonian gravity works just fine, you simply don't know how to follow the math (as usual), this in contrast to Spirals at 200 km/s.
Monkey Butt
4 / 5 (4) Mar 15, 2015
Does anyone have, or know of, a better theory (or hypothesis) than dark matter? How is this theory better than dark matter, at explaining the current state of the universe?
Thank you.
Benni
1 / 5 (6) Mar 15, 2015
Does anyone have, or know of, a better theory (or hypothesis) than dark matter? How is this theory better than dark matter, at explaining the current state of the universe?
Thank you.


A modified Newtonian gravity hypothesis, MOND. It was brought up in a previous post above. It is a modified variation of the Newtonian "Inverse Square Law" of gravity.

MOND hypothesizes that gravity under some circumstances may not always operate in accordance to the Inverse Square Law but may vary from it under conditions slightly less than the Inverse Square Law.

Computer models have been run demonstrating how a small modification to Newtonian gravity is all that is needed to explain how Spiral galaxies can rotate at 200 km/s without flying apart. But keep in mind this modification applies only to Spirals, not Ellipticals whose gravitational dynamics already comply with the Newtonian ISL.

Dethe
1 / 5 (2) Mar 15, 2015
Does anyone have, or know of, a better theory (or hypothesis) than dark matter?
Theory of what? The "dark matter" is just a denomination of observational artifact, i.e. the subject of theories - not the theory as such. If you're dismissing the (existence of) dark matter, then you have nothing to theorize about..
Dethe
1 / 5 (2) Mar 15, 2015
IMO the complete dark matter theory cannot be very simple, because the dark matter is a composite mixture of lightweight particles, heavy photons and scalar waves. But when we are talking about most dominant portion of dark matter, i.e. the scalar waves, then my explanation of dark matter follows & complements the Le-Sage model of gravity. In this model the gravity field results from shielding of (omnidirectional flux of) longitudinal waves of vacuum with massive objects, so that the excess of virtual photons (transverse waves) exists around massive bodies, which manifest itself with lensing and gravity force. But the neighboring massive bodies are blocking the (omnidirectional flux of) longitudinal waves too, which leads into opposite excess of longitudinal waves in vacuum at somewhat larger distance. We already have an observational evidence for it both from shape of dark matter filaments between collinear galaxies, both from gravity effects during solar eclipses and conjunctions.
Dethe
2.3 / 5 (3) Mar 15, 2015
A modified Newtonian gravity hypothesis, MOND
This model is essentially spherically symmetric in the same way, like the Newtonian gravity itself. It cannot explain the existence of elongated dark matter filaments between galaxies, not to say about various particle aspects of cohesive dark matter behavior (dark matter inside of Bullet cluster). Therefore it cannot be applied to both very cold (field based), both very hot (i.e. particle based) dark matter.
Kron
1 / 5 (1) Mar 15, 2015
dark matter is a composite mixture of lightweight particles, heavy photons and scalar waves

You are missing larger objects (brown dwarfs, planets, blackholes etc.) that may be surrounding galaxies, but yes, neutrinos etc and some regular baryonic matter (hydrogen atoms etc) may make up a portion of the dark mass. As it currently appears, all of the known sources of dark mass do not add up to the totals theories call for. The known sources of mass are not enough to explain the missing mass. Dark Matter (whatever it may be) is still required to explain the dark mass. The scalar field you allude to is definitely a running candidate for the explanation of Dark Matter, the so called Scalar Field Dark Matter (SFDM).
Dethe
1 / 5 (3) Mar 15, 2015
As an illustrative analogy may serve the wave behavior around islands. Every undulation or turbulence of water surface exhibits a lensing effect for waves and boats floating around islands. The islands are surrounded with surface coastal waves, which may serve as an analogy of gravity field here. But the underwater waves are shielded with too, which leads into increased turbulence and underwater currents around islands - this is the analogy of dark matter effect. As we know, the additional islands shield the surface waves, but they also make the effects of underwater tsunami waves more pronounced (1, 2). Note the filamentar character of tsunami wave intensity between islands, similar to dark matter between galaxies.
Dethe
1 / 5 (2) Mar 15, 2015
You are missing larger objects (brown dwarfs, planets, blackholes etc.) that may be surrounding galaxies
Of course, the dark matter particles may not have an upper limit, but once they can serve as a source of dark matter effect by itself, I wouldn't call them the dark matter from conceptual reasons. IMO substantial portion of galactic halo which is attributed to dark matter by now is really formed with quite normal atoms, but these atoms are heavily ionized, stripped of electrons - so that they evade an attention in visible spectrum and they're considered as a "dark matter". Such a "dark matter" can be still visible in X-ray of infrared telescopes, though - so I wouldn't consider it a true "dark matter" neither.
Kron
not rated yet Mar 15, 2015
Yes, SFDM speaks of the galactic halo formation in terms of Bose Einstein Condensate drops of scalar field.
vic1248
not rated yet Mar 15, 2015
Who knows?!

Einstein's Cosmological Constant Theory vs. Scalar Fields Theory
http://www.space....rgy.html
Dethe
1 / 5 (3) Mar 15, 2015
SFDM speaks of the galactic halo formation in terms of Bose Einstein Condensate drops of scalar field
Sounds pretty ad-hoced for me, but why not - still better than WIMPs models at GeV spectrum. The physicists should return to Nicola Tesla experiments with scalar waves for to realize, what they're actually talking about (B-E condensate? How? Why?). Also the scalar field cannot be separated form CMB fluctuations which are also tangible evidence of this field (the 2-spin component of it). We aren't required to search for dark matter, we are detecting it routinely for sixty years already.
Benni
1 / 5 (5) Mar 15, 2015
@Dethe,

Succinctly put, the whole problem with your DM model is its' complexity. For starters Astrophysicists already know 60-70% of universal mass is located inside Elliptical galaxies, the remaining 30-40% inside Spirals.

We also know that all Ellipticals have gravitational dynamics that function in perfect accord with the Inverse Square Law, meaning that DM is not needed for 60-70% of the universe to function. Then one day some decades ago some so-called genius gets out of bed after having a dream because he lost something & couldn't find it, then he did & voila DM was born.

As the DM narrative has evolved, something like 85% of the universe is "missing", this in accordance to the rotation rates of Spiral galaxies which make up far less than half the mass in the universe. So DM is the so-called glue needed to hold together the minority structures of the universe together but by some stroke of magic does not have the same effect on the majority structure Ellipticals.

Dethe
1 / 5 (3) Mar 15, 2015
the whole problem with your DM model is its' complexity
This model is conceptually as simple, as the Le-Sage model. The dark matter models cannot be simple at the formal level, because the dark mater is complex mixture of particles, in similar way, like the turbulence at the water surface. So that the complex interpretation of this model is rather feature of this model. Of course we can develop many simpler models (scalar field, quintessence, mirror matter, axions, inflatons, heavy high spin and dark photons, fat strings, sterile neutrinos, chameleon particles, dark fluid and dark baryons, fotinos, gravitinos, ..) - but these models will fail in most of situations, as they're all dealing with particular aspect of dark matter behavior only.
Dethe
1 / 5 (2) Mar 15, 2015
all Ellipticals have gravitational dynamics that function in perfect accord with the Inverse Square Law, meaning that DM is not needed for 60-70%
Wasn't it just you, who talked here, that just these galaxy types create gravity lensing features, which the other galaxies don't? The elliptic galaxies may not exhibit the dark matter rotational curves, but they exhibit the dark matter lensing instead (i.e. their DM effects just apply at larger distance outside of their stars due to their larger mass - but they're still present there). The ellipticals violate the gravitational dynamics - just at the larger distance from galaxy, as it's apparent from this picture of collision. You can be pretty sure, that if some stars could revolve the galaxy at such a distance, they would undergo the dark matter effects heavily.
vic1248
not rated yet Mar 15, 2015
From what I can gather, Dark Matter neither emits nor absorbs light, and it is believed to exist due to its gravitational effects on ordinary matter AND the recent discovery of stars farther away from the centers of galaxies spinning faster than those closer!

Dark Matter has never been directly observed by any means. WIMPs—Weakly Interacting Massive Particles, which are hypothesized to make up Dark Matter, have never been encountered nor did Neutrinos—neutrino & anti-neutrino being the same particle.
Benni
1 / 5 (4) Mar 15, 2015
the whole problem with your DM model is its' complexity
dark matter models cannot be simple at the formal level, because the dark mater is complex mixture of particles


.......alright, you want to be the genius here, so just you explain how DM manages to separate itself from the functioning of Elliptical vs Spiral galaxies? If the DM narrative does not explain the gravitational dynamics of Ellipticals, how does DM figure out how to stay out of those areas of the universe & end up only inside Spirals? Does your DM have a sort of mind"all its' own & by some stroke of magic it knows how to end up only inside of Spirals?

OK, let's try a bit of simple math here: 70% of universe is in Ellipticals, 85% of the universe is DM. But, 70% of the universe does not require a DM presence. So, 0.7 x 0.85= 0.595, then combining:0.85-0.595= 0.255 of the universe is required to have DM if 70% of it does not have it, or we can play around with some other numbers.

vic1248
not rated yet Mar 15, 2015
For what it's worth, it is "hypothesized" that:

Dark Matter constitutes 23% of the Mass-Energy of the Observable Universe.

Ordinary Matter accounts for only 4% of the Mass-Energy of the Observable Universe.

Dark Energy constitutes 73% of the Mass-Energy of the Universe and accelerates the expansion of it.
Dethe
1 / 5 (3) Mar 15, 2015
If the DM narrative does not explain the gravitational dynamics of Ellipticals, how does DM figure out how to stay out of those areas of the universe & end up only inside Spirals?
As I explained above, the DM is the result of shielding effect of all material objects inside of galaxy. If these objects are collinear (as it happens withing spiral galaxies), then even DM remains flat ring, constrained to galactic plane. If these objects are widespread across larger volume (as it's common for elliptical galaxies), then even the DM shadow of galaxy gets larger and widespread outside of galaxy.
70% of the universe does not require a DM presence
Wasn't it just you, who claimed above, that most of gravitational DM effects belongs to elliptic galaxies (which do represent the 70% of universe)? The elliptical galaxies exhibit the DM too, just in form of lensing instead of rotational curves. I'm not trying to play smart here - I just cannot accept the apparent logical fallacies.
Benni
1 / 5 (4) Mar 15, 2015
all Ellipticals have gravitational dynamics that function in perfect accord with the Inverse Square Law, meaning that DM is not needed for 60-70%

Wasn't it just you, who talked here, that just these galaxy types create gravity lensing features, which the other galaxies don't?
Yep

The elliptic galaxies may not exhibit the dark matter rotational curves, but they exhibit the dark matter lensing instead


If they don't follow Rotation Curves for Spirals, how can it thus be implied there is DM present inside Ellipticals to create lensing? If there is no evidence for the presence of DM via "rotation curve" then the lensing is simply caused by the inherent mass of the Elliptical galaxy. You're simply trying to make it sound like gravitational lensing cannot occur except in the presence of DM, and that is dead on wrong because we know our Sun bends starlight & the mass of our sun is 100% accounted for by its' observed mass less any mass transformed to energy.

Dethe
1 / 5 (2) Mar 15, 2015
As I explained above, the center bulge of spiral galaxies would exhibit the lensing in the same way, like the elliptical galaxies (which can be considered as a "naked bulges" from this perspective) - this lensing just cannot be observed due to non-transparency of the galactic disk in its vicinity.
simply trying to make it sound like gravitational lensing cannot occur except in the presence of DM
Of course it can, but it's much weaker than the DM lensing and it also applies to smaller distance. The DM is responsible for roughly 90% of lensing observable. What we are observing around galactic clusters is not gravitational lensing but a dark matter lensing.
Dethe
1 / 5 (2) Mar 15, 2015
we know our Sun bends starlight & the mass of our sun is 100% accounted for by its' observed mass
That's correct, the dark matter lensing cannot manifest for objects INSIDE of our galaxy, which are surrounded with another massive objects from all sides. If some residual dark matter exist there, it remains constrained to solar system plane (ecliptic). Also, the intensity of dark matter lensing is proportional to volume/surface ratio - small objects are therefore affected with dark matter much more, than they affect another bodies with their own dark matter effects. Which is why the small satellites exhibit fly-by anomalies (Pioneer anomaly), whereas the large planets (with large volume/surface ratio) remain virtually unaffected with it.
Benni
1 / 5 (4) Mar 15, 2015
simply trying to make it sound like gravitational lensing cannot occur except in the presence of DM
Of course it can, but it's much weaker than the DM lensing
Boy, you sure know an awfully lot about the effects of something no one has yet proven exists.

The DM is responsible for roughly 90% of lensing observable
This is observably dead on wrong, Astronomers already observe 99.999999% of gravitational lensing only occurs around the disks of Ellipticals which do not have Rotation Curves exhibiting a presence of DM.

Dethe
1 / 5 (2) Mar 15, 2015
It's simple, my dear Watson. The dark matter represents 26% of matter inside of our Universe and it's determined with gravitational lensing. Whereas the normal matter accounts to 4% only - therefore its gravitational lensing must be much 50x weaker, than its dark matter lensing.
already observe 99.999999% of gravitational lensing only occurs around the disks of Ellipticals which do not have Rotation Curves exhibiting a presence of DM
That's OK, because just these heaviest galaxies have dark matter lensing well separated from rotational curves of stars inside of it. I'm explaining it here third time....
Dethe
1 / 5 (3) Mar 15, 2015
This animation illustrates, how/why the dark matter lensing gets separated from its parent galaxy with increasing of its mass. The dark matter is of negative gravitational charge (being formed with excess of scalar waves instead of photons like the normal matter). So it does follow the inflexion point of gravitational potential of normal mater and it gets concentrated at its perimeter the more, the more dense the normal matter is. Therefore the very massive elliptic galaxies have the zone of maximal dark matter density well outside of galaxy and rotational curves of stars. At the case of the heaviest galactic clusters we can observe this separation as so-called dark matter ring.
Uncle Ira
4.4 / 5 (7) Mar 15, 2015
Hooyeei this is a good one. Bennie-Skippy and Zepher-Skippy having a scientifical discussion. I think Zepher-Skippy is winning.
Dethe
1 / 5 (2) Mar 15, 2015
We can also think about dark matter like about sparse antimatter, formed with sparse bubbles filled with excess of scalar (longitudinal) wave energy. Whereas the normal matter has an excess of blobs, i.e. excess of photons (transverse waves). When we shake a mixture of blobs and bubbles, then this mixture will get separated the more, the higher density and gravity field it would have. Therefore small galaxies and stellar clusters have dark matter mixed well with observable matter, but these heavier ones have dark matter expelled at their perimeter - actually the more, the higher mass and gravity they have. This process is not principally different from simple sorting of particle mixtures by their buoyancy: heavy parts will remain at the center, the lightweight bubbles will rise outside of it. Analogously to our solar system - the lightweight gaseous planets remained at its perimeter, whereas the dense planets occupied its center.
Benni
1 / 5 (4) Mar 15, 2015
"This animation illustrates, how/why the dark matter lensing gets separated from its parent galaxy with increasing of its mass"

Well Dethe, you just said it all above which you copied from another site word for word: "This animation....".

Animation & modeling is the sole depth of the selling point of DM because in trying to sell it by observation of the the gravity lensing effects of Spirals vs Ellipticals it becomes a no sell. Most of the universe does not need a DM modeling exercise to explain its' existence, but you can't explain that.

Just tell me, why is it you're unable to explain why most of the universe does not need the funny farm science of DM to explain its' existence in terms of gravity, but you think to the contrary that a phenomena existing the smallest percentage of the universe overrules everything else? What evidence, by other than comical "animations", can you provide for the existence of DM inside Ellipticals? Their inherent gravity doesn't support it.
Benni
1 / 5 (4) Mar 15, 2015
We can also think about dark matter like about sparse antimatter, formed with sparse bubbles filled with excess of scalar (longitudinal) wave energy. Whereas the normal matter has an excess of blobs, i.e. excess of photons (transverse waves). When we shake a mixture of blobs and bubbles, then this mixture will get separated the more, the higher density and gravity field it would have. Therefore small galaxies and stellar clusters have dark matter mixed well with observable matter, but these heavier ones have dark matter expelled at their perimeter - actually the more, the higher mass and gravity they have. This process is not principally different from simple sorting of particle mixtures by their buoyancy: heavy parts will remain at the center, the lightweight bubbles will rise outside of it. Analogously to our solar system - the lightweight gaseous planets remained at its perimeter, whereas the dense planets occupied its center.


This Ira would understand, it's funny farm.
Dethe
1 / 5 (2) Mar 15, 2015
It's also my site. I just explained, why the DM remains OUTSIDE of elliptical galaxies, where it does manifest with lensing (which you admitted already, after all) - but it doesn't interfere the orbital paths of stars INSIDE it. No need to explain it again. BTW Do you have scientific evidence, that the orbital paths inside of elliptical galaxies follow exactly the Newtonian dynamics (a link)?
Benni
1 / 5 (4) Mar 15, 2015
It's also my site
Thus explaining the "funny farm science" part of it & why Ira likes it.

the DM remains OUTSIDE of elliptical galaxies, where it does manifest with lensing
You can't demonstrate DM exists within that proximity of Elliptical galaxies. Just how does the DM figure out how to exist only on the outside of Ellipticals to create lensing, but by some stroke of magic knows how to get inside of Spirals where it is so weak it is unable to create gravitational lensing? Talk about dichotomies or maybe a conundrum, you've become totally confused about the best locations of your fairy dust to do what you want it to do.

(which you admitted already, after all)
Wrong, what I said was Ellipticals have inherent gravity which create gravitational lensing absent the presence of DM.

Do you have scientific evidence, that the orbital paths inside of elliptical galaxies follow exactly the Newtonian dynamics (a link)?
Type the question into any Search
Dethe
2.3 / 5 (3) Mar 15, 2015
SFDM speaks of the galactic halo formation in terms of Bose Einstein Condensate drops of scalar field
The formation of BE condensates requires the temperatures few nanoKelvin above absolute zero. The very light-weight particles would definitely require the temperatures even lower. But the vacuum is filled with CMBR noise at the temperature 2,7 K. Whereas such a temperature may look pretty low for someone, from boson condensate perspective it's still very hot environment. For example the most lightweight known particles like the neutrinos would get a speed around 560 km/sec at the 3 K temperature, which is close to escape velocity at Sun (it affects the distribution of primordial neutrinos around Sun). So I don't see any reason for formation of boson condensates from even lighter particles there.
rossim22
3 / 5 (2) Mar 17, 2015
"This is how science works. Someone notices something unusual, and then people propose theories to explain it. The theory that best matches reality is considered correct."

This comment is an awful description of how science works. This is just how astrophysics has been working for the last hundred or so years, not science as a whole. You don't go from observation directly to correct theory... experimentation and further in situ measurements should be obtained with a hypothesis destined to be either a failure or a step in the right direction. The quote offers no value to alternative hypotheses and puts the cart way before the horse.
Dethe
1 / 5 (2) Mar 17, 2015
This comment is an awful description of how science works
IMO both approaches are OK. As Feynman once said, the true research is if you know, what you're actually doing - everything else is a "stamp collecting". On the contrary, in contemporary science we can often perceive an apparent unwillingness to replicate the unexpected results, which seemingly violate the established theories (cold fusion as a typical example). If nothing else, in science isn't always possible to plan experiments thoroughly before actual finding: many (if not most) of really important findings were accidental - just because they were solely unexpected. This is what makes the science fun and thrilling for scientists, after all.
s_hyama
not rated yet Mar 28, 2015
Flat gravity based on Hubble's law which expanded Newtonian gravity

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