Questions tagged [space-expansion]
The expansion of the universe is a phenomenon wherein, at scales much larger than galaxies, the distance between objects grows over time. This phenomenon is often described as "expansion of space", although there is no difference between space expanding and objects moving apart.
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Curvature of space from approaching gravity sources affecting observations of expansion
Since gravity curves space, I wonder how the locally increasing density of matter and energy due to the current galactic mergers with the Milky Way affects our perception of the universe.
Basically, ...
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Big Bang Escape Velocity
When our entire section of the universe was in a single hot dark dense state, right before our big bang, what was the escape velocity?
user394592
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Another universe due to a rogue wave fluctuation
Let us consider our Universe at its heat death state, and the rogue wave phenomenon that is due to improbable superposition of small waves. Is it possible that a rogue wave-like quantum fluctuation ...
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Growing Hubble sphere
For the past few days I've been going through Baumann's notes on cosmology, more specifically I'm currently busy with chapter 2 Inflation. I don't get how he comes to the following equation involving ...
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Why do successive redshifts multiply rather than add?
I understand the argument presented in the answer to this question on how successive redshifts combine, such that $$1+z = (1+z_1)(1+z_2) = 1 + z_1 + z_2 + z_1z_2 \\ \therefore z = z_1 + z_2 + z_1z_2.$$...
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Was "flow of time" equally fast during the life of universe? Is Doppler Effect the only interpretation of "shift to red"? [duplicate]
I'm an IT developer and recently I created a project where I tried to send signals between two threads in a slowing down environment. I simulated two points with their own clocks and tried to send a ...
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Question on linear perturbations in cosmology
I've been studying clustering dark energy when I came across a paper named "A Short Review on clustering dark energy" by Ronaldo Batista. there are 2 equations in this paper (eq.8 and eq.9) ...
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Questions about cosmic sheets/walls/filaments
I had a couple of questions about cosmic filaments in the context of the cosmic web structure formation:
In this thesis (https://www.imprs-hd.mpg.de/51939/thesis\_cpenzo.pdf), the author indicates in ...
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Cosmological implications of String theory compactification?
Is the process of compactification of hidden dimensions in string theory equivalent to an increasing dilaton field?
Would one expect the compactification process to continue indefinitely?
Could the ...
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Does dark energy get used up in the expansion of the universe?
Now, I am a beginner in Cosmology, so I am not sure if this makes sense.
Since the universe is expanding at an accelerating rate, and thus distant objects are also accelerating away. In that sense, ...
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CMB anisotropies due to moving clusters/voids?
Apparently, there is an effect where a moving overdensity/underdensity (or an object, e.g. a galaxy, moving in an overdensity/underdensity) that is going through an evolution of its gravitational ...
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Can we use the fabric of spacetime to go faster than the speed of light?
If the fabric of spacetime isn't bound by the limit of the speed of light (the universe is expanding faster than the speed of light), could humans somehow wrap a spaceship in a bubble of the fabric of ...
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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, ...
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Can we measure temperature in an isothermal Universe?
It is envisaged that ,in the future ,Universe can end in a big freeze, where there will be no energy gradient. It is also theorised that Universe was isothermal(with some irregularities I guess) in ...
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Does dark energy increase tidal forces in cosmic voids...?
I would like to ask you some questions I have about some interesting work I was reading (https://arxiv.org/abs/1205.4238 & https://academic.oup.com/mnras/article/527/4/11962/7457744) where the ...
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