All Questions
Tagged with cosmology dark-matter
59
questions
50
votes
8
answers
7k
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Why isn't dark matter just ordinary matter?
There's more gravitational force in our galaxy (and others) than can be explained by counting stars made of ordinary matter. So why not lots of dark planetary systems (i.e., without stars) made of ...
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54
votes
4
answers
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How do we know Dark Matter isn't simply Neutrinos?
What evidence is there that dark matter isn't one of the known types of neutrinos?
If it were, how would this be measurable?
- 705
56
votes
4
answers
4k
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Are modified theories of gravity credible?
I'm a statistician with a little training in physics and would just like to know the general consensus on a few things.
I'm reading a book by John Moffat which basically tries to state how GR makes ...
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28
votes
4
answers
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How did the universe shift from "dark matter dominated" to "dark energy dominated"?
In order to get dark energy to dominate, wouldn't you first need another form of energy to push the expansion until dark energy could dominate? Otherwise I don't understand how the universe could ...
- 1,137
22
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2
answers
3k
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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 ...
- 547
19
votes
5
answers
5k
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Dark matter and dark energy references
I've been looking for questions about dark matter, and I've read some very interesting answers. However, I desire too look into it deeply.
This is not actually a question. I'm asking the community ...
10
votes
2
answers
1k
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Dark Matter vs Modified Gravity
Why do cosmologists and astrophysicists assume that the reason for the higher velocities of outer stars in galaxies is due to matter at all? The name dark matter seems misleading. Couldn't gravity ...
- 168
1
vote
2
answers
418
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Possibility of making dark energy equivalent with dark matter
I was curious whether it is possible to make dark energy equivalent to dark matter.
Can this unification be done?
If it can, why do scientists prefer to separate dark energy from dark matter?
29
votes
3
answers
10k
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How do people calculate proportions of dark matter, dark energy and baryonic matter of the universe?
The Wikipedia page on dark matter mentions that the Planck mission had revealed that in our universe ordinary baryonic matter, dark matter and dark energy are present in the ratio: 4.9%, 26.8% and 68....
- 1,057
3
votes
2
answers
1k
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Dark matter and dark energy [duplicate]
Possible Duplicate:
Dark matter references
I have recently read about dark matter and dark energy, and why physicists think it must exist (dark matter: mass of galaxies are far bigger than ...
- 1,503
23
votes
1
answer
9k
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How do we know Dark Matter is non-baryonic? [duplicate]
It seems widely stated, but not thoroughly explained, that Dark Matter is not normal matter as we understand it. Wikipedia states "Consistency with other observations indicates that the vast majority ...
- 3,241
20
votes
3
answers
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Why hasn't warm dark matter replaced cold dark matter as the standard model of cosmology?
The $\Lambda\rm CDM$ (cold dark matter with cosmological constant) is the current standard model of cosmology because the model comes with a long list of phenomena successfully explained by it. ...
- 18.5k
14
votes
3
answers
5k
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How did we 'discover' dark matter? [closed]
I'm an astrophysics student and I've been researching this topic and there is one point that keeps eluding me.
How did the scientific community realize that there had to be dark matter in the ...
- 508
11
votes
2
answers
547
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If neutrinos are disfavoured as DM candidates why aren't axions?
Numerical simulations of observed large-scale structure formation work best with Cold Dark Matter (CDM; see the answer here). Neutrinos are candidates for Hot Dark Matter (HDM), and hence they cannot ...
- 26.8k
9
votes
6
answers
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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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