All Questions
26
questions
-1
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1
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53
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If an area in 2D cannot be curved and finite is the same regarding the space of our pressumed 3D universe?
Is the sentence in the title right that our universe is infinite? And if so does it mean that stars are not evenly distributed along our universe but they all move from a populated centre to a fairly ...
- 2,255
0
votes
0
answers
73
views
Are there any ways to conceptualize the relationship between gravity and space-time other than curvatures?
This might sound like a random question, but it came to me while I was trying to conceptualize the size of the universe and started thinking of entire galaxies resembling grands of sand floating ...
1
vote
0
answers
60
views
Is the universe closed or flat?
Apparently there is a tension in the measuring of the curvature of the universe (https://arxiv.org/abs/2307.07475) as apparently in 2018 the Planck collaboration got a series of results consistent ...
- 2,462
1
vote
3
answers
136
views
Is the solar system sitting in the centre of curved spacetime and if so, are we viewing the rest of the universe from inside that "bubble"?
I read an article about a huge bubble being discovered in which the solar system sits bang in the middle. It got me thinking about the curvature of spacetime. The bubble was created by several ...
3
votes
2
answers
1k
views
Space is flat but spacetime is curved?
In the picture below a triangle has been drawn on a spherical shaped object. The angles add up to 67+48+73=188 degrees. Since the surface of earth is also almost spherical therefore an experiment can ...
- 717
8
votes
4
answers
3k
views
Confusion about the shape of the universe
From what I understood, a Universe with a positive curvature should behave like a sphere, and light will eventually reach the point where it started. Similarly to a ball, when an ant starts to walk on ...
user311398
0
votes
2
answers
60
views
Does the increasing rate of expansion of the universe have any implication on or alter the curvature of the universe?
I'm not really knowledgeable on physics but was curious about this and couldn't find any good answers related to it.
- 3
0
votes
1
answer
135
views
Curved spacetime and geodesics
Is it right to take in account that the Universe might be similar to the Earth regarding curvature so when we look at two galaxies equidistant to Earth but at a right angle observed from Earth their ...
- 467
1
vote
1
answer
226
views
Positive local spatial curvature of the universe implies that the universe is compact (i.e. finite)?
I quote from the Wikipedia page about the shape of the universe:
If the spatial geometry [of the universe] is spherical, i.e., possess positive curvature, the topology is compact.
I'm trying to ...
- 3,369
8
votes
2
answers
377
views
Why does nobody ever consider the possibility that the universe is not smooth?
Disclaimer: I'm not an astronomer, physicist, mathematician, etc. so this is a question from a complete newbie.
One of the greatest mysteries of our age is "where is the dark matter?" The universe ...
- 3,101
0
votes
1
answer
141
views
Evidence for zero curvature of universe (besides CMB)
There is a beautiful argument, based on the spherical harmonics of the cosmic microwave background, which calculates the curvature of the universe.
Are there any other methods of computing the ...
- 394
2
votes
1
answer
92
views
For the case where universe is not flat, has it got an extrinsic curvature towards (an)other spatial dimension(s)? [duplicate]
I got the idea that expansion of the universe is not to somewhere, it is just getting stretched of spacetime since a point of singularity. And I know that universe was calculated as flat (which means ...
- 41
3
votes
1
answer
226
views
Non-integer $k$ value in Friedman-Robertson-Walker model?
I understand that $k$ describes positive, negative, or no curvature. However, why can't there be, for example, +0.5 (semi-positive) curvature, etc?
- 323
6
votes
2
answers
5k
views
Why is the hypersphere not seriously considered by cosmologists as the best model for the overall shape of the universe?
Cosmologists seem to not seriously consider the hypersphere as the best model for the universe even though they mention it as a candidate from time to time. If you look closely, it seems to be a very ...
- 97
3
votes
2
answers
345
views
Is a 4 dimensional spherical universe possible with flat curvature?
I'm trying to understand this snippet from Wikipedia, in particular the section I've emphasized:
The curvature of the universe places constraints on the topology. If
the spatial geometry is ...
- 2,808