Dark Matter

Could you express this mathematically please....?

According to Einstein, gravity is a warp in spacetime caused by matter.

Suppose there are warps in spacetime not caused by matter,a weakness in the fabric of spacetime,so to speak.

This would result in an accumulation of matter,which would warp spacetime to a greater extent than it would in smooth flat spacetime.

Additional matter would increase the “dent” more than “normal”, resulting in the appearance of more mass.

I cannot explain this mathematically.

But even Einstein once said that once the mathematicians got hold of his theory,he didn't understand it himself.

I'm just playing a game in my mind.

As someone once said: ”I don't understand all I know about that”

Here is a link that tells of the frustration in the search for dark matter:

http://www.laboratoryequipment.com/news/2016/07/scientists-looking-invisible-dark-matter-cant-find-any?cmpid=horizontalcontent

Well of course they can't find any, it's invisible! Actually there are many places that suggest that dark matter is there. I think it is likely that it is mostly small black holes, many of them primordial.

Where is the gravitational lens effect to go with these primordial black holes? If you are saying these are black anti-holes, I would come nearer believing you, because these would have the effect of a dispersive lens, in other words, would make the space around them bend "upwards", causing photons and anything else with mass to be deflected away angularly.

My vote still rests with large amounts of anti-matter being present in clumps, clouds, etc. I still suspect antimatter has a negative gravitational charge, that repels ordinary matter. There is no way these clumps could be around if normal matter was attracted. Too many "things" in the dark would bump into each other, go BANG, and release a hell of a lot of energy in less than a femtosecond (or some such unit).

We all need to wait until the lab results are in. It might take even longer than an episode of CSI to get the results back.

The lensing effect is there regardless of whether the galaxy has black holes or even dark matter. It's all a matter of how much mass is there.

http://www.nasa.gov/feature/goddard/2016/nasa-scientist-suggests-possible-link-between-primordial-black-holes-and-dark-matter

On argument there for me! What I have been attempting to speak of is the possibility that anti-matter is also anti-gravity to normal matter, but would have normal gravity to itself. If there is a gravitational charge, it only changes theory slightly, but with very profound results in the discussion about dark matter.

Question: IF space itself is expanding (as mentioned by others here), and light is propagating through that space, does it red shift the light as a matter of course, since the apparent wavelength would be longer by some ratio of speeds? Am I completely all wet on this subject? if space were perhaps "folded with pleats" as a curtain and suddenly stretched out flat does that even matter, since the light apparently can only propagate along the dimensions of normal space. How does that somehow work out to light propagating in a straight line when space is obviously curved. It is difficult for this particular farm boy to get his head around some of these ideas.

"Question: IF space itself is expanding (as mentioned by others here), and light is propagating through that space, does it red shift the light as a matter of course, since the apparent wavelength would be longer by some ratio of speeds?"

Yes it does. see here.

Many years ago when the scientists were looking for ether, they did interferometer experiments to determine if light travelled at different speeds in different directions. No directionality was found, although the experiments were done in a horizontal plane. Usually the experiment rotated the interferometer around a vertical axis to see if the interference pattern shifted left and right. The experiments couldn't detect the influence of gravity as the light beam paths were always perpendicular to the force of gravity. They might have seen something if they did a horizontal vs vertical light path as then the gravity well effect might be noticeable.

The conclusion was that space did not have a grain direction and ether, the medium for light waves, did not flow past earth. An inflation direction, if it affects light red shift, would have to be equal in all directions on earth, which is possible, since the earth is the center of all things.

Jpfalt: "since the earth is the center of all things."

That sounds like a very ancient attitude. Actually, you, yourself are the center of your visible universe. The experts say the universe has no center, but they have been wrong before.

I thought everywhere was the centre of the universe. Every point sees (on a large scale) everything else receding. Just as, in a 2-dimensional analogy, every point on an expanding balloon sees every other point receding.

Exactly what I said. Everyone is at the center of their visible universe. The total universe, which is at least a million times bigger, is unknown.

All for one and all for one. Let me hear it for me!

I almost went there after that comment, but I am being restrained (straight jacket) this morning.

As far as getting coherent radiation from electron beams goes, or inspection of foundry castings with electrons,

(1) how energetic do the electrons have to be in order to pass through cast iron?

(2) There is a "bunching" effect on the electrons as they pass through the magnetic zones, possibly a relativistic effect, I would have to go back and scan the article. This could be the source of any coherence observed, or related to it.

I suspect the electrons themselves did not pass through the (steel, iron) casting. The soft x-rays produced by the abrupt stopping of accelerated electrons are what propagated through the material.

That makes perfect sense to me.

What I recall is that the Betatron was 100KV and I agree that the likely mechanism was soft xray transmission. The nice thing about it was that you had no radiation source when the machine was off, so no safety issues when moving parts into and out of the pit.

If you were referring to the Michaelson-Morley type experiments for determining properties of the aether, then their conclusions were that the aether didn't exist.

To put it another way , they were researching the wrong sort of aether, and cosmologists have been going down blind alleys ever since.

If you turn it around and consider that matter is a phenomenon that appears out of aether like lumps in that cosmic soup of energy, that electromagnetic waves can propagate mathematically without the need for a medium, yet in reality are a consequence of the existence of this all pervading energy, etc etc -( I have been called away, )then you can open your mind up to all sorts of possibllities, including 'actions at a distance 'gravity, electrostatics, how electrons can be in two places seemingly at once etc

Michelson and Morely originally concluded that their equipment was not sensitive enough. It took many years and refinement of their equipment before they decided that the "luminiferous aether" probably did not exist. If I remember correctly, this was not a Eureka moment for these men. They were actually disappointed.

However, I am of the opinion that Dark Matter is today's luminiferous aether. That is, it is a model used to explain the data observed, but it is not the correct model. We are still waiting for the Dark Matter version of the Michelson-Morely experiment. If we use Michelson-Morely as an example, then this experiment may have already been performed. But the experimenters haven't published yet because they didn't get the answer they expected, so they are working on refining their equipment.

Remember, "All models are wrong. Some are useful."

As Peter Mellor quoted in the context of software safety

do we have ' A Model of the Problem or a Problem with the Model ? '

I was suggesting the latter.

Indeed some models are useful provided they don't entice us with seemingly experimental verifications that lead the herd into work on extending the gospel brought about by the new model.

One further thought, somewhere up amongst the contributions above , did I see a reference to the Universe being flat, and which I've seen quoted many times.

Is this a mis-reading of the elastic skin model for representing the effects of gravity around objects ?

This talk of models and interpreting data reminds me of an example from Bertrand Russell about how hypotheses are often tested. He said most people are like the man who, on his way to work in the morning, picks up a copy of the Times before boarding the bus. While reading the paper he sees a headline which startles him and reads the accompanying article, which he just cannot believe.

He is so upset that he gets off the bus at its next stop, goes to the nearest newsstand and buys another copy of the Times. Sure enough, there is that headline and that story. Still not accepting that this could be true, he walks from newsstand to newsstand and buys a Times at each one. Each Times reaffirms what he read in the first. Finally, he gives in and, after seeing the same data each time he looked for it, he accepts that the story is true.

Models must be tested in different ways using different methods, but often experiments are set up to "confirm" the model, not to test it.

In an unrelated aside, your coordinates place you less than 400km from my grandson, who is an exchange student living in Spain this fall term.

Apologies for a repetition but I still think there is some mileage in the idea of the red shift being due units of time changing - but without knowing this or being able to measure it, it appears red to our eyes - and explained as a red shift caused by expansion - except space is the same size as before - distances just seem greater because there are more time units between objects - that without 'factoring/adjusting' in standard equations gives the illusion of being further apart.

The change in time units could be explained by the energy of blue light being absorbed by something invisible currently assumed to be dark matter.

The same 'change' in time causes an acceleration 'felt' as a force we call gravity.

Just a theory for the experts to ponder - they are the ones that seem worried about this.

.....42 is OK with me.

I believe you're starting to understand a concept and complication of spacetime.

I believe you're starting to understand a concept and complication of spacetime.

...If only that were true...

...the only thing I understand is the difficulty of the human mind (well mine for one) being able to embrace the concept of 'infinity' and 'nothing'.

ie, if the Universe is finite what is beyond the edge of the border.

And if the Big Bang was the beginning of our Universe - what was there before.

I am not asking for an answer - I just pose the question asked by lots of people.

We (humans) only have five senses to use for making judgments - which to my mind - five are are not enough to find the answers we seek. Philosophical rather then technical it seems.

I'm just throwing some ideas into the pot

Infinity has no boundary. Therefore nothing can be beyond a boundary that does not exist.

If there was anything prior to the Big Bang it does not matter because it appears to have not influenced our universe. Asking what existed prior to the Big Bang is like asking what kind of a person were you before your father was conceived.

Probably a pretty good ol' boy!

Apparently space cannot exist outside our Universe, since it has not got there yet.

But if out there, (and you are not), be patient, for space will arrive, eventually.

At light speed, time and distance are essentially interchangeable. Try and wrap some neurons around that one. They are "light-years" ahead of us, is actually a redundancy.

It is not logical to assume otherwise, and resistance is futile.

You've got me thinking about this.

If space itself is expanding, then you, I, everyone and everything else must be larger now than, say, this date a year ago. Hubble's constant has been measured to be about 72 km/sec per megaparsec, or a megaparsec gets larger by 72 km each second.

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/hubble.html

Running the numbers, I get that everything has increased in size in the last year by a factor of 7.36 x 10^-11. Of course, this is not measurable, since anything used to measure it has also increased in size by the same factor.

The only way to measure it is to compare a thing with itself in the past. A light wave emitted from an excited atom from a distant galaxy far in the past has expanded in the millions or billions of years it has traveled to earth. Having gotten larger, it is redshifted to a longer wavelength than the same spectral line emitted today.

Then that doesn't explain grade inflation in the schools or hat size growth on some members of this forum.

"...where all the children are above average."

AFAIK Every experiment trying to measure this local spatial expansion has failed to detect this growth. Not even the distance to the moon when measured with laser interferometry over the past 40 years has shown this growth. Maybe sufficient aggregation of matter inhibits this continuation of the Big Bang's spacial inflation.

So you measure the distance that's longer with the yardstick that's longer and get the same answer.

We are not talking about a physical yardstick that can be picked up and held in one's hand.

Think about the standard second, the standard meter, and the standard kilogram.

Have the elements changed their fundamental (basic physics and chemistry behavior), and my answer is a resounding NO! Even though you are stating this change would be of the order of 10^-11/yr, right? That swells to ~10^-2/universe life!!! Changes on that magnitude would be easily observable using fundamental characteristics of matter, except there is no one around to measure it at the beginning or at the end.

How would universal space expansion affect the oscillation frequency of Cesium atoms? If space expanded, but the intrinsic properties of the platinum-iridium alloy did not change, how would the standard meter really be affected? How could the expansion of space possibly affect the standard mass?

Not necessarily. If everything does the same thing at the same time and does it slowly over time, you are dealing with the frog in the pot of water.

If this were true then an expanding universe would be impossible to detect and yet we (CR4) discuss some of the various ways that it has been detected.

We may have detected something, but it could be something else.

My point is that if the metric of space is expanding, it would only be possible to detect this if you could measure something in the present and know how large is was in the distant past. A set of spectral lines emitted in a distant galaxy millions of years ago can be compared with lines emitted from the same element today. For example, hydrogen is shown below with the redshift caused by the expansion of space.

Lines in the optical spectrum of a supercluster of distant galaxies (right), as compared to absorption lines in the optical spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red and beyond (frequency decreases).

"Expansion of space[edit]

Main article: Metric expansion of space

In the early part of the twentieth century, Slipher, Hubble and others made the first measurements of the redshifts and blueshifts of galaxies beyond the Milky Way. They initially interpreted these redshifts and blueshifts as due solely to the Doppler effect, but later Hubble discovered a rough correlation between the increasing redshifts and the increasing distance of galaxies. Theorists almost immediately realized that these observations could be explained by a different mechanism for producing redshifts. Hubble's law of the correlation between redshifts and distances is required by models of cosmology derived from general relativity that have a metric expansion of space.^[18] As a result, photons propagating through the expanding space are stretched, creating the cosmological redshift.

There is a distinction between a redshift in cosmological context as compared to that witnessed when nearby objects exhibit a local Doppler-effect redshift. Rather than cosmological redshifts being a consequence of relative velocities, the photons instead increase in wavelength and redshift because of a feature of the spacetime through which they are traveling that causes space to expand.^[27] Due to the expansion increasing as distances increase, the distance between two remote galaxies can increase at more than 3×10⁸ m/s, but this does not imply that the galaxies move faster than the speed of light at their present location (which is forbidden by Lorentz covariance)."

https://en.wikipedia.org/wiki/Redshift

Yeah, OK, I still think space expands instantaneously, but that is my own quirk to worry about, no one else. Just because nothing is out there (yet), does not mean that space does not continue on even further.

There was a character is "Pushing Daisies" that had a phobia about space suddenly sucking all the air out of the world. He controlled the phobia with a naturopathic antianxiety remedy that smelled and tasted a lot like water.

Maybe you should run over to the tap and get a glassfull.

No thanks. No magic potions here. I am not afraid of space, but I am very afraid of some of the creatures roaming around in it!

According to Guth's theory of cosmological inflation, there was an instantaneous inflation to start and then a gradual expansion which has continued every since. The initial cosmic inflation explains how totally separate parts of the universe could be in thermodynamic equilibrium even though they are too far apart for light (or any other signal) to travel between them in the age of the universe.

History of the Universe - gravitational waves are hypothesized to arise from cosmic inflation, a faster-than-light expansion just after the Big Bang (17 March 2014).^[9][10][11]

https://en.wikipedia.org/wiki/Inflation_(cosmology)

'...Not even the distance to the moon when measured with laser interferometry over the past 40 years has shown this growth....'

.

How do we distinguish 'this growth' from other increases? It is generally accepted that the Moon is spiralling away from the Earth at a rate that puts it about 5 feet further on average from Earth than it was 40 years ago. How do we know that all of that is due to the tides pulling the moon around faster...and not some small portion due to expansion?

Because we understand the kinematics of the Moon, Earth, Sun system from many, many different measurements over millennia. [I always hate to use a lack of evidence in a debate.] If some tiny measurements of the motion of the moon could only be explained by expanding space then science news headlines would be louder than the measurement of faster than light anything. No such claim has been made. Claiming a hidden, unmeasurable, unknowable mechanism is in play is the realm of mystics, not science.

This is the fundamental paradox with Dark Matter. We understand the kinematics of objects moving in space so well that we hurle objects around and out of our solar system with great precision. Even when the tiniest deviation from predicted velocities occur (Pioneer anomaly, Voyager paradox) this measured fractional deviation leads to a better understanding of the universe around us. However, when we study the kinematics of structures much larger in size and mass than our entire solar system the observed kinematics does not agree with theory. They don't disagree with theory by the tiny fractions of the above anomalies, several negative orders of magnitude. They disagree by several positive orders of magnitude. How do we get it so right and so wrong at the same time.

Maybe HTRN made a correct conclusion that the answer to this paradox is not the existence of Dark Matter but some other root cause. I don't know, nobody does know. I do know that many other scientific explorations hinge on the existence of Dark Matter in one form or another. Some of these explorations started with the assumption of the existence of Dark Matter. If HTRN is correct then these plausible attempts will fail. That's how science works.

I'm also far from convinced that 'dark matter' goes beyond the abstract embodiment the inadequacy of our current best understanding.

The Moon is moving away from Earth and the rate of departure is in fine agreement with our laws of physics.... but it is also very close and familiar. Never absent during the development of any of our understanding.

The point being, our models work well for what is familiar, close, and more easily observed/measured. 'Inflation' locally or as it affects similar systems, may have been worked into our models inadvertently because we never knew it any other way.

The breakdown of our models at unfamiliar scales, conditions, times, shouldn't be distressing, the models still work well here/now, we just might not have lucked out with being able to figure out fundamental relations for everywhere and everytime without having to journey beyond the here and now.

When developing his model for gravity Sir Isaac Newton notes considering an inverse relationship to the square of the distance because it fit neaty, not because that's the way it works. We seem to have a lot of examples now where it no longer fits neatly. It would seem removing 'universal' from Newton's laws of gravity (and beyond) would be less of a gamble and far more straight forward than conjuring the bizarre creature needed for our understanding to not actually have been so flawed.

It certainly would be more simple if everything everywhere for all time were governed by the rules set we have locally now, but developing greater understanding does not often give way to large scale simplifications.

As understanding grows, even what initially appear as simple processes later are better seen with a glimpse of complexity and variation as deep as you care to study.

Voyager is officially out of the solar system and is providing some data still. Past voyager, it would seem that any signal received has a significant bias toward being interpreted as though we lucked out with universal rule homogenity.

.

' All models are wrong. Some are useful' - George E.P. Box

And the way I understand astrophysics (very limited amount), something can perturb the moon's orbit and decelerate it to a lower orbit once again.

Sure, something like that could happen. However, the moon would immediately distance itself from Earth, gaining energy and continuing to enlarge the orbit.

With a day that is much shorter than a lunar cycle coupled with a surface of predominantly large bodies of water, the tides will alway treat the Moon like a houseguest who has overstay the welcome...always hurrying

Yeah, I forgot the basic reason why the moon is speeding up. Thanks for the reminder. I am not an astrophysicist. I have not even stayed at a Holiday Inn recently.

If my memory is correct the change in the Moon's orbit will never result in the Moon leaving the Earth. Long before this tiny acceleration achieves escape velocity the expanding Sun will envelop both Moon and Earth.

OR, we will find out what "dark matter" is and translate to the parallel dimensions in another 'brane.

Someone should write a book: "Dark matter: What's the matter with the Universe?"

I can see that flying off bookshelves near you now.

^{Even without getting off the hook by being swallowed by a bloating sun, the tidal acceleration doesn't thrraten to cause a separation.}

^{It is the mismatch between the lunar orbit and the Earth's length of day. As the difference narrows, so does the force of the effect.. Eventually Earth and Moon would have become tidally locked such that the Earth always show the same face to the Moon.}

I agree with your concerns about "universal" laws, though it is not necessarily bad to make the assumption of universality. But you must always be aware of your assumptions.

For example, I am not convinced that this is even the Galactic sign for Choking, let alone the Universal Sign:

On Cirinius Triad, that is the Universal sign for "I am on fire, the Carolina Reaper shipment came in." Little did these smallish aliens know that these peppers were the humans secret weapon for domination of the known universe.

Maybe they're tiny white holes created by the big black hole which has created wormholes....? It's all about the holes....

Obviously, I don't know enough to really make a useful contribution here.

The only thing I will say is that based on the accelerating expansion rate of the Universe, called "inflation", there has to be something causing this, and it is not normal gravity as we understand it. I have heard a hypothesis (not a theory by a long shot), that antimatter and matter have opposite gravitational charges, thus antimatter should float up in a gravitational well. The experiment to test this is soon to be or already taking place near the Large Hadron Collider (at the local antimatter laboratory).

I don't know enough about the test apparatus to comment, although it is reported to be extremely sensitive and will provide an accurate assessment of the situation.

If Einstein's theory of General Relativity holds, then any object, whether it is matter or antimatter, should follow the same path in a gravitational field. Gravity is just bent spacetime and objects move in a geodesic (shortest path) through 4 dimensional spacetime.

http://people.umass.edu/kastor/cosmoslectures/cosmoslecture2.pdf

But General Relativity does not account for the very real possibility that gravitational charges my exist, and that the effect of opposing charge is the opposite of the manifestation of charge forces in E-M theory.

g = -G m₁Q₁m₂Q₂/r² where Q₁ and Q₂ are the mass charges, such that the gravitational acceleration is of the opposite sign when antimatter interacts with normal matter.

The effect in General Relativity would be that in such a case, spacetime would appear as a hill, not as a valley. There really is an experiment pending or underway that will reveal whether or not this is true.

Like you I'm not yet convinced about dark matter.

I wonder if electric and/or magnetic fields might have a much larger effect on the intergalactic medium than astronomers assume. Generally they only count the effects of gravity within a galaxy or cluster of galaxies, presuming the electromagnetic fields to cancel each other out or sum to zero. But maybe the black homes at the centers of galaxies develop a weak positive charge, and the rest of the intergalactic medium develops a negative charge, and the net charge differential is what holds spiral arms together. Sheer speculation, I know.

I think magnetic fields of galaxies have a great deal to do with formation of spiral arm galaxies. What I find absolutely astonishing is that we have the science to measure these (large to very large) magnetic fields through spectroscopy, by the hyper-fine structure of atomic and ionic line spectra. Absolutely amazing, yes?

I think one related effect is the Zeeman effect of atomic spectra, but line width from temperature broadening can wipe this out at medium to low field. I refer the reader to search Herzberg on this topic.

I guess there are a few ways to detect magnetic fields and their directions. Found this:

"Galactic magnetic fields can be observed in the optical range via starlight which is polarized by interstellar dust grains in the foreground. These grains are elongated and can be aligned by magnetic fields, where the major axis becomes perpendicular to the field lines. Measurements of many stars revealed a general picture of the magnetic field in the Milky Way near the Sun. Aligned dust grains also emit polarized infrared emission, which is very useful to show magnetic fields in dust clouds in the Milky Way. Zeeman splitting of radio spectral lines allows measurement of relatively strong fields in nearby, dense gas clouds in the Milky Way. For those three techniques observations in external galaxies are still difficult to obtain. The fourth technique, measuring synchrotron emission, is the most powerful one and can be applied over the whole Milky Way, to nearby galaxies and also to distant galaxies."

Optical image of the spiral galaxy M 51 obtained with the Hubble Space Telescope (from Hubble Heritage), overlaid by contours of the total radio intensity and polarization vectors at 6cm wavelength, combined from radio observations with the Effelsberg and VLA radio telescopes (from Fletcher et al. 2011). The magnetic field follows well the optical spiral structure, but the regions between the spiral arms also contain strong and ordered fields. The bar in the top right corner indicates a scale of 1 arcminute or about 9000 light years (about 3 kiloparsecs) at the distance of the galaxy. Copyright: MPIfR Bonn

http://www.scholarpedia.org/article/Galactic_magnetic_fields

Very interesting, I had forgotten the polarization effects, and where are the alien synchrotron laboratories? -- Just kidding, but no really how does synchrotron radiation arise in a galaxy? Is this through fast motion of circulating charged particles?

It's usually from relativistic electrons from spinning black holes or supernova explosions interacting with magnetic field.

Messier 87's Energetic Jet, HSTimage. The blue light from the jet emerging from the bright AGN core, towards the lower right, is due to synchrotron radiation.

Crab Nebula. The bluish glow from the central region of the nebula is due to synchrotron radiation.

https://en.wikipedia.org/wiki/Synchrotron_radiation

Very nicely done illustration and excellent link. Thank you for the lesson.

Has work continued on undulators (wiggler lasers)? I seem to recall something like that was a hot item in the laser field many years ago.

Very well understood and work out mathematics. I should understand the retarded time axis the best.

Free electron laser, pretty awesome, wide tuning range (microwaves to xrays)...

https://en.wikipedia.org/wiki/Free-electron_laser

I noticed in the link you provided that FELs are being weaponized, presumably up into the multi-megawatt class. I think the current contract is calling for 100 kW class. That could do some serious damage. Is it possible to use a high energy Beta radiation as the beam source? Would it have sufficient energy to make an RF beam laser, or perhaps a maser?

Obviously if the rad source was hot enough, and one had an accelerator contraption, then energies would be higher order relativistic, and could get the beam wavelength a lot shorter.

A beta ray source might be an energetic source of electrons but I think it needs to be collimated for a free electron laser. I think the easiest process is to electrostatically accelerate electrons boiled off of a hot filament as in a CRT.

Back in the '70s, I worked in a steel foundry that used a Betatron for casting inspection. It behaved like an xray, but used accelerated electrons as the radiation. I know that it was not coherent beta radiation. I would assume that you would need a resonance cavity equivalent to get emitted radiation in phase and in alignment.

If there was charge separation as you suggest, then would not the charged gases be attracted (or repelled) as the charge may be, resulting in an outward pressure on gas clouds that were (sic) negatively charged or positively charged? Two gas clouds of opposite net charge would tend to coalesce if near enough for there to be any attractive field.

I would think that over a course of time measured in eons (millions of years perhaps), the charges would result in masses moving to neutralize the charges. The only other way to produce net charges with astronomically high potentials might be hydrogen liquid droplets that pick up static charges as a result of high velocity shear within a gas cloud. Interstellar lightening? IDK. AFAICT this has never been observed in space.

'..Two gas clouds of opposite net charge would tend to coalesce if near enough for there to be any attractive field....'

.

I'm not so sure about that. If it is turbulent enough especially in combination with even low strength magnetic fields, positive and negative clouds would have forces working against their coalescence.

High energy gammas as well as other high energy radiation, once again, especially in the presence of magnetic fields would provide opportunity for ionization and bulk charge separation. Those conditions aren't exceedingly rare.

Point made and taken. Didn't someone else bring up the thing about charged gas clouds in the first place?

There's a nearby galaxy, Dragonfly 44, which appears to be 99.9 percent dark matter, not a subtle discrepancy.

"Astronomers have now identified and described a galaxy made almost entirely of dark matter, the mysterious unseen stuff known to us only via the force of gravity, which also makes up a significant fraction of the mass of the universe. The galaxy is relatively nearby. It’s called Dragonfly 44. It appears dim even through large telescopes, but looks can be deceiving and astronomers now know that there’s more – much more – to this galaxy than meets the eye."

http://earthsky.org/space/dragonfly-44-dark-matter-galaxy-2016

I have recently watched a BBC show on TV where there did not talk about 4 dimensions... but 10 (nowadays there are some discussions saying they are actually 11). A scientist from Princeton explained this theory talking about a watering hose and some ants walking on it. It was quite late, I was half asleep, also may have dozed a couple of times ... but did not get the idea. Has anyone heard about this?

I also remember the show vaguely,but basically it stated that gravity was so weak in our dimension because it was dispersed throughout many dimensions.

A small magnet can overcome the force of gravity of the entire Earth.

It has to do with string theory, which posits that particles are really vibrating strings.

A string can vibrate in a different number of modes depending on how many dimensions or degrees of freedom. For example, a string constrained to remain in a plane would have a certain number of modes of vibration, but if it were allowed to vibrate in three dimensional space, it would have more modes.It turns out that a good match with the "standard model" is an 11 dimensional space.

Where could these dimensions be? They could be rolled up very tightly. An example is a thin wire. It appears to be one-dimensional, but actually the second dimension is "rolled up".

http://whatis.techtarget.com/definition/11th-dimension

Well it's possible our measurement for gravity is wrong...we observe it from within the field itself...It's possible gravity is dimensionally different than we envision...It's possible that gravity is just space/time in another unrecognizable unrealized form....all our observations of gravity are from within a gravitationally effected area, viewing other objects in other gravitationally effected area's....A view of gravity from an unaffected viewpoint might show something quite different...

How unaffected does it have to be to work? You tell me....

Einstein apparently had it right when he added in the cosmological constant (although he got the sign and magnitude of it slightly wrong, I think), then he was embarrassed because he did not like the "symmetry" of his equations, and removed it as if it were an error.

Later on modern physicists have added it back in, and it reveals something about the expanding universe, and the acceleration of the expansion - inflation.

Well I would head north of the equatorial plane for say 50k ly or so....

...or maybe somebody will just figure it out....

http://phys.org/news/2011-12-dark.html

Another proposed explanation of anomalous galaxy rotation is Modification of Inertia by Hubble scale Casimir effect (MIHsC).

"Explanation of MiHsC Theory[edit]

Modification of inertia by a Hubble-scale Casimir effect, or MiHsC, is a theory developed by Mike McCulloch, a physicist at Plymouth University in Plymouth, England. The theory attempts to explain the cause of inertia, which is not completely explained by general and special relativity. MiHsC theory relies on Mach's principle, which states that distant objects can influence inertial mass. But there is a boundary as to how far away the objects influencing inertia can be. This boundary is the point at which light (and therefore any information) will never be able to reach an object because either cosmic acceleration or its own acceleration outpaces the speed of light. Anything beyond this boundary (called the Hubble or Rindler event horizons respectively) is outside the observable universe and therefore can't effect the object at the center of the Rindler space. The Rindler event horizon is effectively the same as a black hole's event horizon. At a black hole's event horizon, quantum virtual particle pairs are occasionally separated by gravity resulting in particle emissions known as Hawking Radiation. For a Rindler horizon, a similar radiation is suspected to exist called Unruh radiation. MiHsC posits that Unruh radiation causes inertia. As a particle accelerates, the Rindler information horizon expands in the direction of acceleration, and contracts behind it. This results in a pressure differential in the Unruh radiation experienced by the accelerating object. More Unruh radiation hits the object from the direction of acceleration, resulting in the effect we observe as inertia. In addition to explaining the EmDrive's motion without violating Conservation of Momentum, MiHsC theory also notably resolves the observed discrepancies in galactic rotation and cosmological acceleration without the need for dark matter or dark energy."

http://emdrive.wiki/Mike_McCulloch's_MiHsC_Theory

http://phys.org/news/2012-09-dark-effect-inertial-mass.html

A very interesting and informative link.

More food for thought for my starving mind;things to digest and mull over as I drift off to sleep at night.

Thanks!

I thought the situation was that when Einstein first came up with general relativity he noticed that it predicted an expanding (or contracting) universe. But everybody at the time "knew" the universe was static, so he (very unscientifically) put in the cosmological constant to give a static solution. If he had had the courage of his convictions and announced that his theory predicted a non-static universe, and then sat back and waited for Edwin Hubble's observations to show (as they did) that it is expanding, Einstein's reputation would be even higher than it is.

I'm also unconvinced about dark matter, and (as a layman) not keen on the way its existence is spoken of as if it's an established fact. Perhaps nobody yet has been smart enough to give the real explanation for the observed effects.

There may be forces that we cannot yet detect that are capable of FTL speed.

We would be unable to detect,or even imagine them with our current technology.

IF dark matter exists,it may be radiating a form of energy that is beyond our ability to measure.

It may even be the source of dark energy,the expansion force of the universe.

Consider radio waves in the 1700's.

They have existed since the beginning of time, yet no one could detect them.

It took centuries to develop the technology to detect and measure them.

Spooky action at a distance may be one form of FTL energy,and there may be others that we have not even imagined.

The problem with spooky action is our grasp can never exceed our reach.

If we wished to talk across the galaxy,first we would have to place a receiver there,which would take longer than conventional means.

It would be good for calling back home in real time.

Another wild arse idea of mine,is that since everything originated from a singularity,we are not ever really separated from any other parts of the universe,and all parts are equidistant from us.

Time and distance are an illusion.

As is reality.

Forces are instantaneous, not traveling. Matter and light are the only "things" that have to obey the speed limit. Even that gets stretched by observable effects, such that some "things" in space appear to be traveling away from each other at >>C. (In this parlance, >>C ≡ 1.01 C and greater.

Dark matter supposedly does not and is forbidden completely to interact with normal radiation by absorption/emission (Einstein radiation laws), and also may only emit radiation that is specifically not EM radiation (not normal photons, waves, etc.).

We don't really even yet know how it interacts with matter, but is related to this mysterious cosmological constant that we know is necessary.

Forces are not instantaneous. Not even gravity is instantaneous. If it were then a gravity wave would not exist.

"Forces are not instantaneous" ... Hmmmm

I'd be inclined to ask: "Does that depend, at all, on what KIND of a force we are talking about?"

Likewise: "How instantaneous would it need to BE, in order for one to consider it as being 'instantaneous'...?"

I envision SOME people as being capable of exhibiting "adamant insistence", as to the "instantaneosity" of their (own) "force" ... (rather humorously, of course). <wink>

Forces are immediate consequences to some interaction of matter, correct? I understand that forces can be applied for a short or longer span of time, that we would still consider to be an instant, or the force could be nearly constant and applied for eons.

That does not change the identity of the force, its vector, or its magnitude, unless some interaction with matter changes.

gravity and magnetism exert force, but propagate at the speed of light. I had wondered at one time whether an optical viewer and a gravitometer looking at a body moving across ones field of view at close to the speed of light would agree in direction to the center of the object. I guess with the detection of gravity waves, the two instruments would point the same direction to the object.

Really! this is sooooo simple.

There's no longer any dark matter because it all got sucked into black holes.

I'm playing a game in my mind too.

This is your brain on Dark Matter....