All Questions
Tagged with dark-energy curvature
12
questions
0
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1
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67
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If space has a positive curvature, is the expansion of the universe caused by time, not "dark energy"? [closed]
Ok, I will assume that space has a positive curvature, where space is the "surface" of this sphere, and time is the radius from the center, so the universe is a 4D hypersphere. Under these ...
- 403
4
votes
1
answer
102
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Sign and physical meaning of the cosmological constant
I've heard that a cosmological constant can be used to model dark energy (e.g. $\Lambda$-CDM model), and that the constant $\Lambda$ should be positive. But my (quite small) understanding of dark ...
- 163
0
votes
3
answers
101
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Question on gravity
Please excuse if my question seems very basic (I'm a lay person fascinated by physics and trying to learn more.) I'm trying to better understand gravity. I have read that "gravity is a natural ...
- 11
3
votes
1
answer
127
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Cosmological constant divergence [closed]
The cosmological constant is measured to be of the order of $10^{120} $ smaller than the value which has been calculated from quantum mechanics. As far as I know, usually this divergence is attributed ...
user336075
0
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1
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133
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Shape of the universe as dark energy starts to dominate
We say that the universe has a particular shape (flat, sphere or saddle) depending on what the ratio between the average energy density and the critical energy density is, something we call $\Omega$.
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3
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1
answer
263
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How could the universe be spatially flat on average, if all forms of energy have positive spatial curvature?
EDIT: I stated the current understanding wrong, thanks Koschi for the comment.
In the $\Lambda$CDM model, it's said that the vacuum energy pretty much "balances" the baryonic matter, such ...
- 2,475
8
votes
1
answer
726
views
Can a closed universe become open?
My feeling is that no a closed universe can't become open. Under normal evolution according to the Friedman equation the curvature would be more exagerated as time goes on (i.e. a a closed universe ...
- 59
3
votes
1
answer
298
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Flat universe and changing energy/matter ratios
Of what I understand, current observations indicate the universe curvature is closely a flat one. This is made possible since adding up the energy densities of regular matter, dark matter and dark ...
- 33
6
votes
2
answers
767
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How can a cosmological constant be a candidate for dark energy if the universe is flat?
How can a cosmological constant be a candidate for dark energy if the universe is flat? Doesn't a cosmological constant in EFE give rise to positive/negative or no curvature to the universe? I mean, ...
- 75
3
votes
3
answers
592
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Is the universe flat?
There are more than one way to view the description of the universe as flat. There is the description of an open, flat or closed universe in terms of it's fate, expansion forever away from gravity, or ...
- 231
28
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2
answers
4k
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Why does dark energy produce positive space-time curvature?
My understanding is that dark energy, or equivalently a positive cosmological constant, is accelerating the expansion of the universe and I have read that this gives empty space-time positive ...
- 3,500
3
votes
3
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480
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asymptotic curvature of the universe and correlation with local curvature
There is not-so-rough evidence that at very large scale the universe is flat. However we
see everywhere that there are local lumps of matter with positive curvature. So i have several questions ...
- 14.5k