All Questions
18
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Can there be structures made from neutrinos that can have angular momentum?
Would it be possible to eventually have structures made from neutrinos somewhere in the universe, as it is indicated in this question (Are neutrino stars theoretically possible?), like halos of ...
- 2,462
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33
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Turnaround radius being increased in fast collapsing regions?
In the context of formation of large-scale structures, there would be a turnaround radius where expanding matter would detach from the Hubble flow and start to collapse (https://www.aanda.org/articles/...
- 2,462
1
vote
2
answers
59
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Interplay between gravity and cosmic expansion causing collapse of large-scale structures?
As far as I understand it, in the context of large structure formation, the interplay between gravity and cosmic expansion can cause certain anisotropies in voids that can make them collapse (https://...
- 2,462
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Can the integrated Sachs-Wolfe and the Rees-Sciama effects have any influence on matter?
CMB photons can be affected by the expansion of the universe through the linear integrated Sachs-Wolfe effect (ISW) 1 and the non-linear ISW effect or also called Rees-Sciama effect 1.
In particular, ...
- 2,462
1
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44
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Effects of dark energy in the kinetic energy of a body?
If I launch a ball into the sky it would reach a distance after which it would return into the ground transforming the potential energy into kinetic energy as it hits the ground
This is similar to ...
- 2,462
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votes
2
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44
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Age of the universe due to expansion
"If gravity working on matter is the only force at work on large scales, then the attactive force of gravity will act to slow the expansion. In this case, the universe was expanding more rapidly ...
2
votes
2
answers
87
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Why the megaastrophysical objects do not collapse due to their gravitational selfattraction?
At the largest scale in the universe exist formations called filaments which form something like a spider web along the whole universe. But they seem to be quite static. So my question is about the ...
- 2,255
9
votes
1
answer
356
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Why are galaxies much closer spaced (relative to their size) than stars?
I have read this question:
So the average spacing is somewhere in the range of 10 - 100 times the size of the biggest galaxies. The peas I had for lunch today were (at a guess - I didn't measure them!...
- 29k
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votes
1
answer
71
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Does the energy density of the universe decrease when objects become gravitationally bound?
We know that the mass of an Iron nucleus is proportionally lower than the mass of a hydrogen nucleus (a proton) compared to the sum of the individual nucleons. This is due to the binding energy of the ...
- 1,720
1
vote
1
answer
55
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Galaxy Superclusters
Okay quick question... why is it that when galaxies group together in superclusters they form a sort of branch-like shape? I personally would think they’d all just group together in some sphere or ...
- 31
1
vote
2
answers
98
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Will Earth be devastated when the orbit shifts 1 metre towards the Sun? [closed]
There are some arguments in my country from a population that they are "religious". Then, their argument is that there is a perfect balance in universe and solar system.
Hence they say that Earth ...
- 65
1
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2
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388
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Confusion regarding the concepts and derivation of Hydrostatic Equilibrium for a star
First and foremost I am sorry for this; in order to make the questions clear I must first upload the lecture notes from my institution $^\zeta$ for the derivation of Hydrostatic Equilibrium:
$^\...
- 2,470
0
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1
answer
262
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Can a photon attract another photon? [duplicate]
Now since Photons have energy too, is it possible for these particles to gravitationally attract each other.
- 1,368
6
votes
2
answers
283
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How does the inclusion of vacuum energy modify Newtonian gravity equation of motion?
The equation of motion (in the center of mass frame) due only to gravitational forces between two point masses is:
$$\frac{d^2r}{dt^2} = -\frac{GM}{r^2}$$
How does the equation get modified when a ...
- 5,412
2
votes
0
answers
59
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Any method to determine the gravitational constant $G$ from observations in cosmological scale?
By the observations in cosmological scale, I mean observations by astrophysicists like motions of quasars in far distance from us, relative motions of our galaxy to others, etc.
I know the famous ...
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