Dark Matter

[arkie87]

A question i've had for a long time:

It is my understanding that after inputting galaxies into computer simulations, and giving stars velocities similar to the measured ones, the galaxies flung themselves apart in stark contract to reality. Accordingly, physicists have suggested that there is dark matter, which cannot be directly observed.

My question, therefore, is: why cant this dark matter be just that: dark matter. The sun constantly gives off solar wind (and i assume most starts do). If it has been burning for billions of years, it might have lost a significant amount of mass, which has cooled and is floating around the solar system (but is un-observable).

From Wikipedia:

Mass of Observable Universe: 1e53 kg

Volume of Observable Universe: 4e80 m3

Average Density: 2.5e-28 kg/m3, which is approximately equal to 1/7th of a proton per cubic meter

The average density of interstellar space is 0.1-1000 atom (i assume this means proton) per cubic centimeter: i.e. 1e-22-1e-18 kg/m3

The Mass of the Milkyway galaxy: 3e42 kg

The volume of the Milkyway galaxy: 1e61 m3

The average density of the milkyway galaxy is 6e-19 kg/m3

Thus, the upper limit of average density of interstellar space is close to the average density of the milkway galaxy, and so, rarefied gas could be some dark matter?

Am i failing to consider something, or worse, miscalculating something?

[Brotoro]

"Dark“ means that we can't detect this matter by any kinds of electromagnetic emission or absorption (not just that it isn't visibly glowing). We can detect the amount of gas in interstellar space because of its emission (hydrogen, for example, radiates at 21cm radio wavelength...and gets ionized and glows visibly as "HII regions" when excited by UV from nearby hot stars) or absorption (interstellar gas can show up as absirption lines in starlight that passes through it).

Whatever dark matter is, it does not radiate in ANY part of the EM spectrum.

[NFUN]

The theory that the extra gravity is provided by [relatively] normal baryonic matter is called MACHO, for Massive COmpact Halo Objects. In general, the theory of WIMPs, Weakly Interacting Massive Particles, fits observations better than MACHO.

[arkie87]

"Dark“ means that we can't detect this matter by any kinds of electromagnetic emission or absorption (not just that it isn't visibly glowing)...

Whatever dark matter is, it does not radiate in ANY part of the EM spectrum.

I understand that; my question is: why is that our conclusion. Isnt the answer i proposed simpler (and thereby, satisfies Occam's Razor)? How can we really know the density of of interstellar space?

- - - Updated - - -

The theory that the extra gravity is provided by [relatively] normal baryonic matter is called MACHO, for Massive COmpact Halo Objects. In general, the theory of WIMPs, Weakly Interacting Massive Particles, fits observations better than MACHO.

In what way(s)?

[Brotoro]

I understand that; my question is: why is that our conclusion. Isnt the answer i proposed simpler (and thereby, satisfies Occam's Razor)? How can we really know the density of of interstellar space?

As I said, normal matter is detectable because of its emission and absorption of various wavelengths of electromagnetic radiation. We can measure how much gas and dust is in the interstellar medium in several ways, such as the strength of the absorption lines, the extinction and reddening of light from distant stars, the dispersion of pulsar pulses of different frequencies, etc. We know how much of that stuff there is from these observations.

NFUN mentioned Massive Compact Halo Objects (things like sub-stellar mass objects loose in interstellar space and black holes) that we could not easily observe by their emissions, and which are also made of baryonic matter. But if there were a lot of these things, we would see a lot more gravitational lensing events as they pass between us and distant stars, but we don't...so we have a limit on that stuff as well.

When all the things that could be seen were added up, the tally fell well short of the amount of mass needed to keep our Galaxy rotating the way we observe it to rotate.

Edited August 23, 2015 by Brotoro

[arkie87]

As I said, normal matter is detectable because of its emission and absorption of various wavelengths of electromagnetic radiation. We can measure how much gas and dust is in the interstellar medium in several ways, such as the strength of the absorption lines

If the absorption lines become saturated, can we still tell how thick the gas clouds are? Or we tell by band widening? How does it work? How do we detect clouds if there are no stars behind it or how do we know the cloud is in our galaxy and not on the outskirts of another galaxy, if the stars we observe are in another galaxy?

Thanks for your response(s)

[Glaran K'erman]

I understand that; my question is: why is that our conclusion. Isnt the answer i proposed simpler (and thereby, satisfies Occam's Razor)?

A) Occam's Razor doesn't mean squat here unfortunately, life just ain't that simple.

Regarding OP, what about the fact that nothing has blocked our view of the stars (for the technically inclined I know I'm "wrong", just simplifying for the point)? Wouldn't some chunk or cloud of this stuff pass through an object and a telescope pretty often if it were so common? Also you seem to be lumping together dark MATTER and dark ENERGY, which is actually pretty OK to do since we really don't know much about either and they often get lumped together. But you seem to oversimplifying what this stuff actually is, I highly suggest reading some very boring and dry science articles (not research papers but whatever your upper limit is for technicality) and watching stuff on YouTube if you get bored, but once you do I think you'll be very capable of answering your own question.

[Brotoro]

If the absorption lines become saturated, can we still tell how thick the gas clouds are? Or we tell by band widening? How does it work? How do we detect clouds if there are no stars behind it or how do we know the cloud is in our galaxy and not on the outskirts of another galaxy, if the stars we observe are in another galaxy?

Thanks for your response(s)

I don't make these kinds of measurements, so I don't know if the lines are saturated. I wouldn't expect them to be because the stuff is pretty thin in most directions.

We get information about where the gas doing the absorbing is located by the doppler shift of the lines. If it's gas in another galaxy doing the absorbing, it would exhibit a redshift that matches that of the other galaxy. If it's an intergallactic gas cloud between us and a far away galaxy, the absorption lines due to the cloud exhibit a redshift of something less than that of the distant galaxy. In our own Galaxy, we can use the doppler shift of the 21cm radio emissions from neutral hydrogen clouds (the intensity of which depends on the amount of hydrogen) to map the locations of hydrogen clouds because of the slightly different doppler shifts that we expect to observe from different directions in our rotating Galaxy.

A certain fraction of interstellar gas gets ionized by stellar UV (the amount of which is calculable from the known UV flux and the density of the ISM), and the electrons from those ions affect the travel speed of radio waves coming to us from pulsars, so that a pulsar pulse is received at slightly different times for different frequencies.

[UmbralRaptor]

If the absorption lines become saturated, can we still tell how thick the gas clouds are? Or we tell by band widening? How does it work? How do we detect clouds if there are no stars behind it or how do we know the cloud is in our galaxy and not on the outskirts of another galaxy, if the stars we observe are in another galaxy?

Gas clouds glow. Radio surveys of cold gas work with various emission lines (notably the 21 cm atomic hydrogen line), and emission lines give you convenient velocities. Gas clouds observed around other galaxies follow the weird rotation curve of the stars out beyond any substantial stellar light.

Hot x-ray emitting gas is another source. IIRC, the amount and temperature of gas we find in various large clusters (eg: Coma) is such that it should leak out without a great deal of additional mass. And then there are cases of colliding clusters where we can see majority of the mass is not located where the majority of the baryons are.

[PB666]

Gas clouds glow. Radio surveys of cold gas work with various emission lines (notably the 21 cm atomic hydrogen line), and emission lines give you convenient velocities. Gas clouds observed around other galaxies follow the weird rotation curve of the stars out beyond any substantial stellar light.

Hot x-ray emitting gas is another source. IIRC, the amount and temperature of gas we find in various large clusters (eg: Coma) is such that it should leak out without a great deal of additional mass. And then there are cases of colliding clusters where we can see majority of the mass is not located where the majority of the baryons are.

Actually the majority of non-stellar hydrogen is in intergalactic space, because of the dynamics of the surrounding galaxies the gas is very hot (remember that space is not like atmosphere, the gas travels for days before colliding into another gas particle), and this means it has moved millions of miles and the collisions are much higher energy, in the UV to Xray range. Added to this galaxies with massive black holes are basically belching highly energized plasma and hydrogen into the poles over galaxies which are basically in a very steep elliptical orbit around the galaxy, its very hot stuff, not to us, because space is a vacuum and we would simply dehydrate and freeze solid, but when two hydrogens smack each other there is alot of hv.

[mpc755]

The mass which fills 'empty' space is beginning to be referred to as the 'dark mass' in order to distinguish it from the baggage associated with dark matter.

'Dark Energy/Dark Mass: The Slient Truth'

https://tienzengong.wordpress.com/2015/04/22/dark-energydark-mass-the-silent-truth/

"That is, all that we are certain about [is] the dark mass, not dark matter, let alone to say about the dark 'particle'."

What physics mistakes for the density of the dark matter is actually the state of displacement of the dark mass.

Particles of matter move through and displace the dark mass, including 'particles' as large as galaxies and galaxy clusters.

'The Milky Way's dark matter halo appears to be lopsided'

http://arxiv.org/abs/0903.3802

"the emerging picture of the dark matter halo of the Milky Way is dominantly lopsided in nature."

The Milky Way's halo is not a clump of dark matter traveling along with the Milky Way. The Milky Way's halo is lopsided due to the matter in the Milky Way moving through and displacing the dark mass, analogous to a submarine moving through and displacing the water.

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

The Milky Way moves through and curves spacetime.

The Milky Way's halo is curved spacetime.

The state of displacement of the dark mass is curved spacetime.

The state of displacement of the dark mass is gravity.

Edited August 23, 2015 by mpc755

[SAI Peregrinus]

mpc755 got any sources that don't get basic QCD wrong? 'cause that looks like crackpottery, not science. ALL the quarks are visible (interact electromagnetically), including the antiquarks. If even your most basic starting premise is utterly incorrect, there's certainly more wrong later, but it's not worth the time to check.

[K^2]

Yeah, that article is just a mess of nonsense.

[PB666]

mpc755 got any sources that don't get basic QCD wrong? 'cause that looks like crackpottery, not science. ALL the quarks are visible (interact electromagnetically), including the antiquarks. If even your most basic starting premise is utterly incorrect, there's certainly more wrong later, but it's not worth the time to check.

Clarifying. The photo is its own antiparticle. So basically either form of matter is visible in light, and likewise at high energy photons can generate both forms of matter at the same time.

[mpc755]

mpc755 got any sources that don't get basic QCD wrong? 'cause that looks like crackpottery, not science. ALL the quarks are visible (interact electromagnetically), including the antiquarks. If even your most basic starting premise is utterly incorrect, there's certainly more wrong later, but it's not worth the time to check.

'Dark matter' is now understood to fill what would otherwise be considered to be empty space.

'Cosmologists at Penn Weigh Cosmic Filaments and Voids'

http://www.upenn.edu/pennnews/news/cosmologists-penn-weigh-cosmic-filaments-and-voids

"Dark matter ... permeate all the way to the center of the voids."

'No Empty Space in the Universe --Dark Matter Discovered to Fill Intergalactic Space'

http://www.dailygalaxy.com/my_weblog/2012/02/no-empty-space-in-the-universe-dark-matter-discovered-to-fill-intergalactic-space-.html

"A long standing mystery on where the missing dark matter is has been solved by the research. There is no empty space in the universe. The intergalactic space is filled with dark matter."

I use the term 'dark mass' to describe the mass which fills 'empty' space. Particles of matter move through and displace the dark mass, including 'particles' as large as galaxies and galaxy clusters.

In the following two articles the aether is what waves in a double slit experiment. In the first article the aether has mass. In other words, it is the dark mass that waves in a double slit experiment.

'From the Newton's laws to motions of the fluid and superfluid vacuum: vortex tubes, rings, and others'

http://arxiv.org/abs/1403.3900

"This medium, called also the aether, has mass and is populated by the particles of matter which exist in it and move through it" ...

... and displace it.

'EPR program: a local interpretation of QM'

http://arxiv.org/abs/1412.5612

"Wave particle duality is described as the compound system of point particle plus accompanying wave (in the æther)."

Q. Why is the particle always detected traveling through a single slit in a double slit experiment?

A. The particle always travels through a single slit. It is the associated wave in the dark mass which passes through both.

The wave of wave-particle duality is a wave in the dark mass.

Here are some articles where the observed physical phenomenon is correctly described by the matter moving through and displacing the dark mass.

'Galactic Pile-Up May Point to Mysterious New Dark Force in the Universe'

http://www.wired.com/wiredscience/2013/01/musket-ball-dark-force/

"The reason this is strange is that dark matter is thought to barely interact with itself. The dark matter should just coast through itself and move at the same speed as the hardly interacting galaxies. Instead, it looks like the dark matter is crashing into something  perhaps itself – and slowing down faster than the galaxies are. But this would require the dark matter to be able to interact with itself in a completely new an unexpected way, a “dark force†that affects only dark matter."

It's not a new force. It's the dark mass displaced by each of the galaxy clusters interacting analogous to the bow waves of two boats which pass by each other.

'The Milky Way's dark matter halo appears to be lopsided'

http://arxiv.org/abs/0903.3802

"the emerging picture of the dark matter halo of the Milky Way is dominantly lopsided in nature."

The Milky Way's halo is not a clump of dark matter traveling along with the Milky Way. The Milky Way's halo is lopsided due to the matter in the Milky Way moving through and displacing the dark mass.

'Offset between dark matter and ordinary matter: evidence from a sample of 38 lensing clusters of galaxies'

http://arxiv.org/abs/1004.1475

"Our data strongly support the idea that the gravitational potential in clusters is mainly due to a non-baryonic fluid, and any exotic field in gravitational theory must resemble that of CDM fields very closely."

The offset is due to the galaxy clusters moving through and displacing the dark mass. The analogy is a submarine moving through the water. You are under water. Two miles away from you are many lights. Moving between you and the lights one mile away is a submarine. The submarine displaces the water. The state of displacement of the water causes the center of the lensing of the light propagating through the water to be offset from the center of the submarine itself. The offset between the center of the lensing of the light propagating through the water displaced by the submarine and the center of the submarine itself is going to remain the same as the submarine moves through the water. The submarine continually displaces different regions of the water. The state of the water connected to and neighboring the submarine remains the same as the submarine moves through the water even though it is not the same water the submarine continually displaces. This is what is occurring as the galaxy clusters move through and displace the dark mass.

'Hubble Finds Ghostly Ring of Dark Matter'

http://www.nasa.gov/mission_pages/hubble/news/dark_matter_ring_feature.html

"Astronomers using NASA's Hubble Space Telescope got a first-hand view of how dark matter behaves during a titanic collision between two galaxy clusters. The wreck created a ripple of dark matter, which is somewhat similar to a ripple formed in a pond when a rock hits the water."

The 'pond' consists of dark mass. The galaxy clusters are moving through and displacing the dark mass. The ripple created when galaxy clusters collide is a wave in the dark mass.

What ripples when galaxy clusters collide is what waves in a double slit experiment; the dark mass.

Einstein's gravitational wave is de Broglie's wave of wave-particle duality; both are waves in the dark mass.

Dark mass displaced by matter relates general relativity and quantum mechanics.

[YNM]

I'll just quote myself over what "dark matter" is :

"Dark Matter" is an amount of mass that's calculated to exist via gravitational observations (empty areas gravitational lensing within clusters, superclusters or around interacting galaxies, then rotation speed in the disk of spiral galaxies), but can't be observed visually, or through other means (yet, hopefully). There have been speculations what is it actually. It may be an usual particle (baryonic), matter that's normally present (consider brown dwarf, planemo, gas cloud, white dwarf, red dwarf etc. that's not easily observable on distant galaxies), but it's harder to think how could there be a lot of these things between two faraway galaxies, as to those within clusters and superclusters; hence why there're also non-baryonic (unusual particles, protons neutrons quark lepton etc. are considered normal / baryonic) solution such as WIMPs (weakly interacting massive particles, the name reflects what is it supposed to be - a particle that interacts only via gravity and weak force). Neutrinos are also proposed, as they do interact gravitationally.

Other explanation is called MOND (modified newtonian dynamics), where they propose it's because the characteristics of gravity itself. But it mostly fails over explaining the empty area lensings, other part of the explanations still makes some sense (even it tries to address out dark energy).

@mpc755: welp, you've pointed that aether-like thing in a previous thread. If you want to be deaf let yourself be deaf, don't ask someone else to be deaf as well. I'll just note: matter in the universe is non-homogeneous at small scale, even when all thing is added, and if it's that homogeneous, you won't observe orbital motion.

@OP: Why it can't be just "dark matter" ? It is indeed just dark matter ! Main problem lies in when there's not enough source, and people want a solid explanation.

[mpc755]

@mpc755: welp, you've pointed that aether-like thing in a previous thread. If you want to be deaf let yourself be deaf, don't ask someone else to be deaf as well. I'll just note: matter in the universe is non-homogeneous at small scale, even when all thing is added, and if it's that homogeneous, you won't observe orbital motion.

'Empty' space has mass which is displaced by the particles of matter which exist in it and move through it, whether you choose to correctly understand what occurs physically in nature or not.

[SAI Peregrinus]

'Empty' space has mass which is displaced by the particles of matter which exist in it and move through it, whether you choose to correctly understand what occurs physically in nature or not.

It has mass and that mass gets displaced by nearby particles (has volume)... So basically it's matter.

Also, if it gets displaced how does that displacement happen? What interaction occurs? Is there a new fundamental force involved? If not, how has this new force avoided notice> That is possible, but it would have to be very weak, so if so please prove that it would be weak enough to avoid notice but still strong enough to cause the displacement. Is there a reaction force, or does it violate Newton's third law? If it violates the third law, does it obey conservation of momentum? If so, how? You say your "dark mass" relates GR and QM, how precisely does it do so? Can you point to an actual predictive theory in mathematical terms or just make analogies in English? If the former, what are some testable predictions of the theory? Can you provide predictions of the power spectrum of matter in the large scale structure of the universe? If not, why not? Every other theory of gravitation can answer all of these basic questions quite easily.

[K^2]

'Empty' space has mass which is displaced by the particles of matter which exist in it and move through it, whether you choose to correctly understand what occurs physically in nature or not.

All theoretical predictions that say vacuum has mass have an error of approximately 100 orders of magnitude. It is known as the biggest failure of modern theoretical physics. So you can stop right here. We have absolutely no idea what's going on with dark matter or dark energy at this point.

[mpc755]

All theoretical predictions that say vacuum has mass have an error of approximately 100 orders of magnitude. It is known as the biggest failure of modern theoretical physics. So you can stop right here. We have absolutely no idea what's going on with dark matter or dark energy at this point.

'Dark matter' is now understood to fill what would otherwise be considered to be empty space.

'Cosmologists at Penn Weigh Cosmic Filaments and Voids'

http://www.upenn.edu/pennnews/news/cosmologists-penn-weigh-cosmic-filaments-and-voids

"Dark matter ... permeate all the way to the center of the voids."

'No Empty Space in the Universe --Dark Matter Discovered to Fill Intergalactic Space'

http://www.dailygalaxy.com/my_weblog/2012/02/no-empty-space-in-the-universe-dark-matter-discovered-to-fill-intergalactic-space-.html

"A long standing mystery on where the missing dark matter is has been solved by the research. There is no empty space in the universe. The intergalactic space is filled with dark matter."

I use the term 'dark mass' to describe the mass which fills 'empty' space. Particles of matter move through and displace the dark mass, including 'particles' as large as galaxies and galaxy clusters.

Edited August 24, 2015 by mpc755

[YNM]

You're confusing dark matter with dark energy as well now...

Edited August 27, 2015 by sjwt

[mpc755]

You're confusing dark matter with dark energy as well now...

All I did was post two quotes from two articles which state dark matter fills 'empty' space. Neither had anything to do with dark energy.

Our Universe is a larger version of a galactic polar jet.

'Was the universe born spinning?'

http://physicsworld.com/cws/article/news/46688

"The universe was born spinning and continues to do so around a preferred axis"

Our Universe spins around a preferred axis because it is a larger version of a galactic polar jet.

'Mysterious Cosmic 'Dark Flow' Tracked Deeper into Universe'

http://www.nasa.gov/centers/goddard/news/releases/2010/10-023.html

"The clusters appear to be moving along a line extending from our solar system toward Centaurus/Hydra, but the direction of this motion is less certain. Evidence indicates that the clusters are headed outward along this path, away from Earth, but the team cannot yet rule out the opposite flow. "We detect motion along this axis, but right now our data cannot state as strongly as we'd like whether the clusters are coming or going," Kashlinsky said."

The clusters are headed along this path because our Universe is a larger version of a polar jet.

It's not the Big Bang; it's the Big Ongoing.

The mass which fills 'empty' space is beginning to be referred to as the 'dark mass' in order to distinguish it from the baggage associated with dark matter.

Dark energy is dark mass continuously emitted into the Universal jet.

Our Universe is a larger version of the following artist's image of a galactic polar jet.

The Milky Way moves through and displaces the dark mass.

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

The Milky Way moves through and curves spacetime.

The Milky Way's halo is curved spacetime.

The state of displacement of the dark mass is curved spacetime.

The state of displacement of the dark mass is gravity.

Edited August 27, 2015 by sjwt

[K^2]

mpc755 A few of your links were to media covering scientific publications, and mostly, misquoting sources, as popular coverage usually does. The rest is just nonsense from the start.

I'm telling you that as someone who actually spent a number of years studying particle physics.

Edited August 27, 2015 by sjwt

[mpc755]

mpc755, A few of your links were to media covering scientific publications, and mostly, misquoting sources, as popular coverage usually does.

I'm telling you that as someone who actually spent a number of years studying particle physics.

As someone who spent a number of years studying particle physics are you able to understand the particle always detected traveling through a single slit in a double slit experiment is evidence the particle always travels through a single slit?

You do understand in a boat double slit experiment the boat travels through a single slit even when you close your eyes, correct?

Q. Why is the particle always detected traveling through a single slit in a double slit experiment?

A. The particle always travels through a single slit. It is the associated wave in the dark mass which passes through both.

Edited August 27, 2015 by sjwt

[SAI Peregrinus]

In the double-slit experiment if you send a particle through it will always travel through a single slit. If you send a wave through it will always travel through both slits. If you send a quantum through it will travel through either one or both slits depending on how you set up the experiment. Therefore quanta can behave somewhat like both particles and waves. Your mistake is assuming that things like photons or electrons are particles, when they're not, they're quanta. People call them particles due to a historical accident and because it's a little easier to introduce the concept to young children that way.