Mystery of dark matter may have been solved

ChrisIB

Honorable
Mystery of dark matter may have been solved by Oxford scientists
The mysterious dark substances are not covered by the existing mathematical model of the universe - known as LambdaCDM - but they are known to exist because of their gravitational effects.

Now scientists have proposed a new model which unifies dark energy and dark matter into a single phenomenon - a fluid which possesses "negative mass".

Dr James Farnes, who led the team at Oxford's e-Research Centre, said: "We now think that both dark matter and dark energy can be unified into a fluid which possesses a type of 'negative gravity'.
The idea of negative matter was previously ruled out because it was thought the material would be less dense as the universe expanded - something which observations involving dark matter did not support.

However the Oxford team applied a new "creation tensor" to the model which allowed for negative masses to be continuously created.

The tensor demonstrates that when more and more negative masses burst into existence, the new material - the negative mass fluid - does not become diluted due to the universe's expansion.
I get that tensors are just scalars and vectors but negative gravity? how does that relate to the curvature of space time?
 
Hahaha...this is hilarious. So, for 70 years the mainstream physics community has been heaping ridicule and scorn upon the ufology community because witnesses have been describing the levitation of these devices as "antigravity." And nearly all of the academics cried out that antigravity was physically impossible because 1.) it would violate the positive energy theorem - this turned out to be untrue, and 2.) it would appear to require the existence of matter with negative mass, which they said was absurd and impossible.

Then in 1998 we discovered that the galaxy clusters are accelerating away from each other; in other words, there's an antigravitational field acting between the galaxy clusters. That was such an embarrassing finding that they've been calling it "dark energy" instead of "antigravity" ever since.

And now it appears that there may be a fluid of exotic matter (i.e. that possesses negative mass) surrounding the galaxy clusters, which is producing both "the dark matter effect" (in this model the negative mass fluid is producing an antigravitational acceleration upon the galaxies from the outside, thereby producing the illusion of "missing matter" within the galaxies) and also "the dark energy effect" which is accelerating the galaxy clusters apart from one another. And in this model, this negative mass fluid is being created right now as part of the natural dynamics of the universe. So if this model is correct, then we should eventually be able to make this stuff in the lab. If that's true, then we'll eventually be able to build our own UFOs, and conduct rapid manned missions to other star systems.

Here's the link to the full 20-page paper. This should be a fun read:

http://inspirehep.net/record/1644598/files/1712.07962.pdf

I get that tensors are just scalars and vectors but negative gravity? how does that relate to the curvature of space time?
Usually when people talk about tensors, they mean a rank-2 tensor, which is defined by a matrix. Rank-0 tensors are scalars, rank-1 tensors are vectors, and rank-2 tensors are matrices (in general relativity gravity is described by a rank-2 tensor, the Einstein tensor). That's how GR describes the manifold of spacetime; it's a higher order than a vector equation.

We've known that the dark energy effect manifests as a negative gravitational field since 1998. Negative gravity, or if you prefer, "antigravity," curves spacetime in the opposite direction from ordinary gravitation. So if you think of the gravitational field around a planet or a star as a "well," then negative gravity can be thought of as a "hill." A negative gravitational field also produces a gravitational blueshift, instead of the ordinary gravitational redshift. This stuff isn't theoretical anymore, it's now a key feature of modern astrophysical studies that are examining an effect known as the late-time integrated Sachs-Wolfe effect. Counterintuitively, this effect "warms" photons from the cosmic microwave background radiation when they pass through regions of higher density like galaxy clusters, and "cools" photons that pass through supervoids where the dark energy effect (aka antigravity) dominates.

Generally relativity always permitted negative gravity. In fact the cosmological constant that Einstein invented to produce a static universe - before we learned about the Big Bang which rendered that notion obsolete, is a negative gravity term in the Einstein field equation - they brought it back when we discovered the dark energy effect. But if this theory is correct, then "the cosmological constant" isn't a constant after all - it's produced by a fluid with negative mass which gathers around galaxy clusters in the form of gigantic halos.
 
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Dejan Corovic

As above, so bellow
Yeah, hopes are high, but lets not get overheated.

I've seen papers where autors claimed that galaxies spin faster just because of lots of matter that hadn't been accounted for inside galaxies (don't have link). It still could go both ways.

This new theory seems to be testable in a simple way with radio astronomy. So we might know soon.

There is a really easy to understand description of Sach-Wolfie's effect here:

Integrated Sachs-Wolfe Effect
 
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Dejan Corovic

As above, so bellow
Counterintuitively, this effect "warms" photons from the cosmic microwave background radiation when they pass through regions of higher density like galaxy clusters, and "cools" photons that pass through supervoids where the dark energy effect (aka antigravity) dominates.

Is it possible that "warm" and "cool" should swap the places here because it makes it difficult to understand? When photons pass through galaxy clusters they are redshifted to longer wavelengths as they lose energy. Loss of energy means that photons are "cooled", since cooling means lowereing enrgy. Opposite, when photons pass through supervoids they gain energy and photons are blueshifted or "warmed". Gaining energy makes somthing warmer.

I know that in human terms red is warm, and blue is cool, but in reality that's illusion caused by presence of water molecules in our body. And water molecules are of the similar wavelength as IR and red wavelengths so water heats up and we feel warmer.
 
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Is it possible that "warm" and "cool" should swap the places here because it makes it difficult to understand? When photons pass through galaxy clusters they are redshifted to longer wavelengths as they lose energy. Loss of energy means that photons are "cooled", since cooling means lowereing enrgy. Opposite, when photons pass through supervoids they gain energy and photons are blueshifted or "warmed". Gaining energy makes somthing warmer.

I know that in human terms red is warm, and blue is cool, but in reality that's illusion caused by presence of water molecules in our body. And water molecules are of the similar wavelength as IR and red wavelengths so water heats up and we feel warmer.
Look at it this way: in an otherwise unchanging universe, a photon approaching a galaxy cluster gets blueshifted as it approaches the center of the gravity well (with respect to an observer at that center of the well), and then gets redshifted by the exact same amount as it exits the gravity well. There would be no net change in the energy.

But the universe is evolving. Galaxy clusters are constantly coalescing into more tightly bound conditions (each star is undergoing fusion, for example) which releases radiant energy (light) into the cosmos at large - so galaxy clusters are slowly losing mass. And therefore the gravity well of a galaxy cluster grows slightly more shallow over time. So the photon approaching the galaxy cluster gets blueshifted (gains energy) as it approaches the center by a greater degree than it gets redshifted on the way out, because the gravity well isn't quite as deep as it exits the other side, hundreds of thousands or millions of years later. So it ends up slightly blueshifted, aka "warmer," by the time it reaches our telescopes. The inverse effect happens with respect to supervoids, which causes the photon to end up with a lower energy and frequency, i.e., it becomes "cooler."

That's why I said that the late-time integrated Sachs-Wolfe effect is counterintuitive, at first blush anyway.
 

Dejan Corovic

As above, so bellow
Look at it this way: in an otherwise unchanging universe, a photon approaching a galaxy cluster gets blueshifted as it approaches the center of the gravity well (with respect to an observer at that center of the well), and then gets redshifted by the exact same amount as it exits the gravity well. There would be no net change in the energy.

I understand your explanation, but don't they teach in textbooks that superclusters red-shift passing photons? Wasn't that a reason why superclusters look a bit yellowish/golden? We don't see blue shifting from photons that pass through clusters?
 
I understand your explanation, but don't they teach in textbooks that superclusters red-shift passing photons? Wasn't that a reason why superclusters look a bit yellowish/golden?
Well, there are two additional things to consider here. One, a photon originating within a gravity well will be redshifted, and two, the Hubble expansion and the cosmological acceleration produce a cosmological redshift. And of course there are Doppler redshifts and blueshifts to consider as well, due to incidental velocity differentials. They have to account for all of that stuff to tease out the ISW effect signals.

We don't see blue shifting from photons that pass through clusters?
Sure we do - that's the strongest part of the ISW effect signal. Photons passing through, or by, galaxy clusters are definitely left with a detectable warming, i.e., a residual blueshift, because the net galaxy cluster mass drops somewhat during the long transit period. The cooling from the supervoids is a much weaker signal, but they say they've detected it and the current surveys are honing those signals, so it's not purely theoretical anymore.
 
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Shadowprophet

Truthiness
I would be more impressed but it's honestly about damn time. 70 plus years three generations. It's too long to wait.
 

Shadowprophet

Truthiness
never gonna happen
possibly, But consider this, Negative mass and Charge, That's Really just Antimatter, We are already creating that at CERN, The Idea is in a particle accelerator This positively charged matter strikes a-Grounded copper plate, While Production of antimatter is only like 1 part per billion, We still manage to create antimatter in this way,

If I was a betting man, A metamaterial made of some form of Copper could, in theory, produce Antimatter if a strong enough negative charge was applied to it.

But, That's really just a Theory I have.
 

humanoidlord

ce3 researcher
possibly, But consider this, Negative mass and Charge, That's Really just Antimatter, We are already creating that at CERN, The Idea is in a particle accelerator This positively charged matter strikes a-Grounded copper plate, While Production of antimatter is only like 1 part per billion, We still manage to create antimatter in this way,

If I was a betting man, A metamaterial made of some form of Copper could, in theory, produce Antimatter if a strong enough negative charge was applied to it.

But, That's really just a Theory I have.
uhhh, i don't think antimatter has negative mass, because if it had, it would fall up!
 

Shadowprophet

Truthiness
uhhh, i don't think antimatter has negative mass, because if it had, it would fall up!
Right you Are, I was thinking of Negative Charges, When I read that, Of course, matter has positive mass, Lol, My bad, If it's any consolation, I had just finished smoking a huge joint, My bad :)
 

Dejan Corovic

As above, so bellow
In this video, at 16:37, Milky Way's halo is discussed. Basically, galactic halo is a sphere that has diameter of 600,000 ly and Milky Way is a pancake with diameter of only 100,000 ly. Size ratio Halo vs Spiral Arms is 6:1. Halo is full of old stars and no new stars are forming there right now. In 2012 observations with Chandra satellite estimated that mass of the stars and interstellar gas in galactic halo is approximately the same as of those in that galactic disc.

If that was to be confirmed with some other observation, than that would pretty much spell the end of the dark matter idea across the whole universe. Dark Matter's fame mostly sprung out of the fact that galactic spiral arms are rotating faster than what would be calculated from galactic mass only. But at that time nobody knew how many stars are inside galactic halo. Now one can say that a huge mass of the galactic halo is pulling onto the matter inside the galactic disc and make the disc spin faster. That explanation can easily do away with the Dark Matter.

 
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ChrisIB

Honorable
Dark matter is on the move: Scientists find the material can be pushed out of a galaxy's center | Daily Mail Online
A new study suggests dark matter, the invisible material that makes up about 27 percent of all matter, can be heated up and moved around by processes that occur within galaxies.

As new stars form, the resulting winds push aside gas and dust, removing mass from the center of the galaxy and with it, much of the gravitational pull that holds dark matter in.
‘Our finding that it can be heated up and moved around helps to motivate searches for a dark matter particle.’
 

ChrisIB

Honorable
Now scientists have proposed a new model which unifies dark energy and dark matter into a single phenomenon - a fluid which possesses "negative mass".
What might be the ramifications? Does the physics of black holes permit something with negative mass to escape?
Could the galactic centred super massive black holes be fountaining out dark matter energy?
 

Dejan Corovic

As above, so bellow
There is a commentary for Jamie Farnes' paper by Matt from YouTube channel PBS Spacetime



Basically Matt is criticising Farnes' theory because it would require negative curvature universe and it doesn't agree with supernova observations that led to discovery of dark energy.
 
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