All Questions
Tagged with cosmology space-expansion
1,604
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Horizon problem, what if our observable universe is roughly equal to the whole universe, especially in early times?
How do we know that at a time of 380.000 years, when CMB got free, the observable universe was not equal to the actual universe? Maybe they were roughly the same and couldn't that explain the horizon ...
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Does neglecting dark matter solve the Hubble tension?
If the total mass of the universe is smaller than estimated by neglecting the gravitational pull of dark matter, the estimated expansion rate should be greater.
Does this consideration in the CMB ...
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Solutions for nonrelativistic-matter perturbations
I'm studying the nonrelativistic-matter perturbations if the expansion of the Universe
is driven by a combination of components.
I'm currently Following this document (The growth of density ...
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42
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Up-tunneling of vacuum with high-energy events?
I was reading these papers by Sean Carroll (https://arxiv.org/abs/1405.0298 ; https://arxiv.org/abs/1505.02780) in which, among other things, he argues against vacuum up-tunneling occurring in the ...
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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/...
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Why are physicists not more concerned that there are too many explanations for redshift in the universe?
There are speculative explanations for red shift such as the tired light theory, but I am not referring to those. There are three mainstream explanations
Red shift due the expansion of the universe ...
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Does expansion with dark energy drive Universe to increasing flatness?
One of the successes of theory of inflation is its explanation for the flatness of the Universe at the start of the Big Bang. Simply stated, in the Friedmann equation, the inflation field energy ...
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Why is it mysterious that space is apparently expanding at different rates everywhere? [closed]
New-ish measurements from Hubble + Webb say that the Universe is expanding at different rates everywhere: https://www.livescience.com/space/cosmology/james-webb-telescope-confirms-there-is-something-...
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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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608
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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 ...
- 735
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46
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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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