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

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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
81 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 ...
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1answer
95 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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65 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
54 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 "problem"...
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299 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 ...
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5answers
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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
384 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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28 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 ...
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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
44 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 ...
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1answer
40 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 ...
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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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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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4answers
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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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2answers
517 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
331 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 ...
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3answers
352 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 ...
6
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1answer
205 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
201 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
467 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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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
266 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
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Is there a binary black hole system in the middle of the galaxy? [closed]

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 ...
3
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1answer
106 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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2answers
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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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196 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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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 ...
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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 radii?...
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1answer
146 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 ...
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2answers
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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 ...
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1answer
117 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 ...
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1answer
187 views

Do most physicists believe that axions exist? [closed]

Is the theoretical justification behind proposing axions sufficiently robust, like, say the Higgs boson prior to its detection, that one should consider the existence of axions as generally accepted (...
3
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1answer
181 views

Could Hyper-Massive Black Holes be due to Dark Matter in the Early Universe?

An interesting discussion started here: Is there a limit as to how fast a black hole can grow? I am curious if Thompson Scattering and Eddington Luminosity have the same effect on Dark Matter (or ...
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1answer
169 views

What is dark matter composed of? [duplicate]

They say that about 80% of the matter in the universe is dark matter -- some unknown substance that has mass. But what is this matter expected or speculated to be composed of? For example might it ...
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1answer
133 views

WIMPs - would they be charged?

I'm no expert in this stuff, it's just a hobby to me, but I've been reading up on the WIMP theory a bit - layman articles, not published research. From Wiki on Dark Matter: It also cannot ...
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130 views

How much dark matter is needed to gravitationally distort light?

I understand that dark matter only has a gravitational property. It does not interact directly with regular matter or EM radiation. The evidence for dark matter comes from observations that contradict ...
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Why does the amount of dark matter increase the further away from the galaxy's center?

Why isn't the dark matter just randomly distributed? How does it know where to go?
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What is meant by “shallow density profile” in the context of dark matter halos?

Evidently there is a consensus about the density profile of dark matter at large distances from the centers of galaxies, but it is not known whether their density profiles are "shallow" or "cuspy". ...
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How does mirror matter account for the faster than expected spin of gallaxies?

To explain dark matter, some physicists have postulated the existence of mirror matter as an alternative to WIMPs, where mirror matter particles could interact with one another in the same way as ...
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2answers
863 views

What is a reasonably accurate but simple model of the Milky Way's gravitational field?

I am putting together a toy program which shows how stars move around in the galaxy. To run the simulation I need to know strength of the Milky Way's gravitational field at any location in it. I'm ...
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What exactly is 'Dark Matter'? [duplicate]

There are many documentaries, forums, blogs and more dedicated to Dark Matter. I have been frantically searching for an answer to my question however none of my sources have clarity to the matter of ...
9
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1answer
292 views

Can curvature waves in f(R) theories explain gravitational lensing in cluster collisions?

The Einstein-Hilbert action leading to Einstein's equations is $$S\sim\int R \sqrt{-g}\, {\rm d}^4 x$$ There is a class of modifications of Einstein's relativity called $f(R)$ theories of gravity ...
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1answer
190 views

Dark matter, dark energy [closed]

As I understand dark matter and dark energy are quite theoretical . That modern theories require the existence of these phenomena. I read a lot of information about this. And I realized that ...
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2answers
99 views

Why is dark matter used to explain big movements but not small ones

Just read that there are perturbations of stuff in the outer solar system that suggest there are Earth sized planets far out from the sun, in the dark. When the same sort of effects are seen at the ...
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1answer
181 views

Could the dark matter sector be boring?

People always talk about finding good dark matter (DM) candidates of beyond Standard Model (SM) theories. To be a proper candidate the particles should not decay into the SM particles and could ...
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2answers
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Why are neutrinos ruled out as a major (or even sole) component of dark matter?

A number of times I have encountered in text-books and articles that neutrinos might contribute only a small fraction to dark matter. The reason has to do with the fact that if all of the dark matter ...
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1answer
156 views

What physical processes can convert dark matter into dark energy?

In this news article, it is mentioned that it could be the case that some physical processes convert dark matter into dark energy http://physicsworld.com/cws/article/news/2014/nov/18/is-dark-energy-...
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213 views

Has the idea of holeum been debunked?

Here is the wikipedia article. The basic idea is that the primordial density of microscopic black holes was high enough that many were able to form stable bound states before decaying through Hawking ...
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A Theory of Almost Everything? [closed]

Before I present this theory, I ask that you take the time to read this disclaimer. I do not claim to have an excellent knowledge of physics, it is actually rather limited. Therefore, I am not ...