Matter not observed directly but inferred to exist based upon its gravitational effects

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3answers
52 views

Why is the ratio dark matter / normal matter bigger today than in the past? Is it the dark matter that increased or the normal matter that decreased?

These two pie charts clearly show that the ratio dark matter / normal matter is bigger today than it was in the past. But why? How is it possible? And does it mean that the amount of dark matter ...
2
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4answers
516 views

Redshift of light in dark matter

Following Edwin Hubble, it is widely believed that the universe is expanding, which is based on the red-shift of light from distant objects. Can dark matter cause light to be red-shifted and make it ...
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1answer
92 views

Could M-Theory explain dark matter as well as dark energy?

Is it possible that M-Theory provides a solution to the mystery of dark matter and dark energy? The idea of dark matter and dark energy is that there is some inexplicable source affecting our ...
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6answers
88 views

Can dark matter be converted to dark energy?

According to energy mass conversion law, mass can be converted to energy. So is it possible to convert dark matter into dark energy?
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1answer
116 views

Spiral galaxies and gravity lenses

Spiral Galaxies must have a great deal more mass than elliptical galaxies of the same size in order to account for the flat velocity curve. I've seen references of eight to ten times the visible ...
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2answers
100 views

Origin of cusps in simulated dark matter halos

I keep reading that cusps are one of the most "robust" predictions of N-body simulations of dark matter halos. But papers I've found on the topic make it sound like these simulations are complicated ...
4
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0answers
83 views

Is MOND dead or still being actively researched?

This may be an opinion based question, and if so I shall remove it, but is MOND, Modified Newtonion Dynamics, pretty much dead as both a theory/ hypothesis and also as an active research subject? ...
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0answers
20 views

DGP brane world model

Can we think of interaction between dark energy and dark matter within the brane in DGP model like in case of GR?
14
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5answers
472 views

How does dark matter collapse?: Entropy considerations

Inspired by this question. I believe that the usual explanation that preserves the second law of thermodynamics as an astrophysical gas cloud collapses under gravity is that the gas must heat and ...
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1answer
899 views

How can dark matter collapse without collisions or radiation?

I understand that dark matter does not collapse into dense objects like stars apparently because it is non-interacting or radiating and thus cannot lose energy as it collapses. However why then does ...
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1answer
35 views

Is there a real and relevant relationship between Big Bang and dark matter?

Since the postulate of dark matter is based on the unexpected rotational velocity around the centre of a spiral galaxy, then it can be presumed that the Big Bang Theory is not relevant to the search ...
4
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1answer
86 views

Where would the dark matter particle fit inside a picture of the standard model of particle physics?

Where would the dark matter particle fit inside a picture of the standard model of particle physics? While I am particularly fond of the Sterile Neutrino, I have not been able to find any example of ...
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0answers
42 views

Could there be a dark matter planet? [duplicate]

Since dark matter is gravitationally "charged", by which I mean it has mass and attracts things, could it bunch together to form a planet?
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1answer
46 views

Could dark matter be degenerate?

If dark matter were to be partly composed of fermions (such as hypothetical neutralinos), then could these particles be subject to degeneracy pressure if they were trapped in the potential well of a ...
1
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1answer
46 views

Dark energy and exotic states of space-time

So far as I know attempts to detect new particle that responsible for the nature of dark matter/energy are not successful. And there are reasonable explanation for this, like energy levels we can get ...
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0answers
137 views

Is the Milky Way's halo curved spacetime? [duplicate]

This question has nothing to do with dark matter. This question is discussing a theory which states the notion of dark matter is incorrect and the Milky Way is moving through and displacing the 'dark ...
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0answers
38 views

Why do planets moving around our Sun lead to how stars move around the centre of a spiral galaxy?

We know that the speed with which the planets go around our sun decreases as a function of the distance they are from the sun. Since stars are not planets, and presumably do not behave like planets, ...
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1answer
30 views

What is the current state of axion research theoretically?

Is the problem (the strong CP problem) that is solved by axions still considered a really big problem, like the missing mass terms that could be solved by the Higgs mechanism? Or is it more a ...
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0answers
243 views

Dark matter clumping [duplicate]

How can dark matter particles (WIMP's) get ever more densely clumped during the evolution of the universe, as we see for example in the Millennium simulation, if they can't loose kinetic energy by ...
3
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5answers
1k views

Why can't “missing mass” (=dark matter) be photons?

After a star lives and dies, I assume virtually all of its mass would be photons. If enough stars have already lived and died, couldn’t there be enough photon energy out there to account for all ...
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2answers
282 views

When will physics understand it is the 'dark mass' not the 'dark matter'? [closed]

There is new thinking occurring in physics where 'dark matter' is considered to be incorrect. The new thinking is that mass fills 'empty' space. The mass which fill's 'empty' space is being referred ...
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2answers
139 views

Is there a confirmation of dark matter signal?

Dark matter, as we know does not emit light, so confirmation of its presence is indirect. Are there any recent indirect confirmations of dark matter. A place one would look for in detecting dark ...
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3answers
338 views

Where is all the Dark Matter? Theoretical Question

In my Physics Class we had to look into possible areas where Dark Matter could be "hiding." Such as Black Holes and so on. Dark matter really can be "seen" through its gravitational effects, and we ...
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0answers
22 views

Electroweak symmetry breaking with additional gauge group(s)

Is it possible that rather than the electroweak splitting into SU(2)xU(1), that there could instead of another gauge group in the dark sector? Suppose SU(2)xU(1)xSU(N)_d. Is that ruled out by the full ...
28
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3answers
2k views

Can the Sun capture dark matter gravitationally?

I think my title sums it up. Given that we think the dark matter is pseudo-spherically distributed and orbits in the Galactic potential with everything else, then I assume that its speed with respect ...
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1answer
42 views

is electromagnetic phenomena and particle behavior dependent on dark matter?

Dark matter permeates space and coalesce s in its own gravitational attraction. It neither absorbs or emits light or interacts well with baryonic matter. It deflects light on a path and is the sub ...
2
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1answer
31 views

Neutrinos born before inflation

What would happen, if there was (hypothetically, for any reason) a very large number of neutrinos+antineutrinos before the inflation period. They probably dont like to annihilate too much. I would ...
5
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1answer
855 views

Can Dark Matter just be clumps of Neutrons

I was wondering about Dark matter, and it occurred to me that why could it not be just nuclei of Neutrons with no electron cloud. Is it possible for such things to exists. Can Neutrons bond to one ...
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1answer
95 views

I wonder what kind of proof we have that dark matter is really made of not-yet-discovered WIMP particles and not WISPy? [closed]

There is quite reasonable argument by Joerg Jaeckel that dark matter might be actually very light, very weakly interacting particles, so-called WISPs (for weakly interacting slim particles), as ...
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1answer
86 views

Gravitinos the key to theory of everything?

Theory of everything The theory of everything aims to unite all the four forces of nature into one single elegant equation. Super-symmetry Super-symmetry is important as it explains the nature of ...
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3answers
113 views

Dark matter: Will Special Relativity hold?

Part 1: It’s been said that dark matter makes up about 26 % of the universe. The restart of LHC would be dealing with the existence of dark matter also. Consider a situation that the results are ...
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5answers
591 views

Why dark matter and general relativity?

My knowledge on this subject is minimal, so sorry if my question is obvious. But why is the current consensus that there is something called dark matter rather than that our current theory of gravity ...
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3answers
274 views

How do we know dark matter isn't curved spacetime?

Could Dark Matter actually just be spacetime with curvature "leftovers" from the big bang or the inflationary epoch?
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1answer
94 views

Is dark matter moving faster than light? [closed]

My way of thinking is as follows: Consider a balloon. Let this be blown into a nearly elliptical sphere. Now, the temperature inside the balloon is increased by some means; this leads to the ...
3
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3answers
290 views

How much of the universes mass is bound up in photons traveling between stars?

I was watching a Scott Manley video on youtube and he mentioned that the Sun was loosing 4 million tons of mass a second as it converts to energy. With a few trillion trillion stars also converting ...
5
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1answer
83 views

Experimental Data for Mass Distribution of a Galaxy

My goal here is not to discuss dark matter in general. I know there are many other observational clues that hint us towards Dark matter. My goal is simply to understand this argument here a little ...
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2answers
142 views

Relation between $\Lambda$ and $\Omega_\Lambda$ in $\Lambda\mathrm{CDM}$

In minimal $\Lambda\mathrm{CDM}$, there is a parameter labeled $\Omega_\Lambda$, and current fits place it at around $\left( \Omega_\Lambda \sim 0.73\right)$. Meanwhile, $\Lambda$ enters the Einstein ...
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2answers
377 views

Does it make sense to continue searching for dark matter on Earth?

The Large Underground Xenon Detector (LUX) recently released results1 that they have found no signs of dark matter2 after a ~3 month search this spring and summer. The LUX group plans to spend all of ...
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2answers
65 views

Has energy in 'transit' been incorporated into missing matter calcs.?

Has energy in 'transit' been incorporated into missing matter calcs. ?It would seem that, although very small in mass, the sheer number of particles shhoting about from one end of the universe to the ...
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2answers
76 views

Distribution and detection of dark matter

I feel in the dark (no pun intended :), I'm sure most of you are familiar with this image I pulled from wikipedia: The caption reads: "3D map of the large-scale distribution of dark matter, ...
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2answers
1k views

Is there a binary black hole system in the middle of the galaxy?

We have observed gravity effects from black holes in the center of galaxies, but galactic centers are dusty so we can’t tell if it’s one black hole or two black holes in a binary system in there. A ...
2
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1answer
63 views

Wouldn't dark matter throw off the calculation of Earth's 'light' mass and estimates of its composition?

The Cavendish experiment first determined the mass of the Earth and (arguably) the gravitational constant. However, given the ubiquitous nature of dark matter, it seems reasonable that at least some ...
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3answers
520 views

Theory that gets rid of dark matter/energy

Is there any physics theory that either groups together gravity and dark energy/dark matter or eliminates dark energy/dark matter by modifying standard understanding of gravity or any force? If so, ...
4
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2answers
80 views

Distribution of dark matter in galactic halos

Often dark matter around galaxies is referred to as a 'halo'. I've seen the galactic rotation curves, but I'm having trouble visualizing how the dark matter is distributed for a typical rotating ...
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2answers
137 views

Missing Matter Problem and Galactic Kinematics

This is a re-wording of an earlier problem I posted. The standard example of the Missing Mass Problem comes from the rotational profiles of galaxies. By counting up the visible matter, we extrapolate ...
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2answers
90 views

Can you collide with dark matter?

Assuming dark matter has space and weight, can dark matter collide with others planet? If unlike normal matter, dark matter repels matter, Will it makes dark matter impossible to collide with normal ...
4
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3answers
365 views

Why is the dark matter density profile within the solar radius (and local density) uncertain?

It seems that we know the rotation curve inside the sun's galactic orbit fairly accurately. Then wouldn't we be able to just take the derivative* of this to get the DM density profile at smaller ...
0
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1answer
71 views

Galaxy rotation curve

In calculating galaxies' rotation curve, it is assumed that masses outside the orbit has no contribution and masses inside the orbit can be deemed as if they were at the center, just like the case of ...
3
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2answers
154 views

On non-local physics in cosmology by prof. B.V. Alekseev

Recently I've encountered work by prof. B.V. Alekseev, in which he claims that some physical problems can be easily solved if we consider non-local interactions in kinetic theory (interactions of ...
2
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1answer
94 views

Can observations of cosmic super voids teach us anything about time, dark energy, or dark matter?

Can observations of cosmic super voids teach us anything about... Time - If gravity affects time is there a chance we could gain any further information from studying a region with lower than ...