All Questions
6 questions
1
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Present value of the cosmological scale factor, important or arbitrary?
I'm now confused about a subject that I thought was very clear to me, until recently. So I need to sort this clearly once and for all. Consider the standard FLRW cosmology in classical general ...
- 7,677
2
votes
0
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119
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Formula to get scales of the two components (radial and perpendicular) of Baryonic Acoustic Oscillations (BAO)
In an astrophysics context about BAO (Baryonic Acoustic Oscillation), it is written on the following paper BAO paper :
"BAO are much smaller in amplitude than the CMB acoustic peaks, and are ...
user87745
1
vote
1
answer
58
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If space expands, why does a liter of water stay a liter? [duplicate]
From observing the universe, we know that space expands.
I see what that means on cosmic scales.
But what does it mean on smaller scales?
If I have a graduated beaker of 2 liter, and 1 liter of ...
- 3,966
0
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1
answer
65
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Cosmological densities when universe was/will be a different size
Supposing a spatially flat, matter-dominated universe, the expression for the Hubble parameter is:
$$ H^{2}=H_{0}^{2}\left(\frac{\Omega_{m}}{a^{3}}+\Omega_{\Lambda}\right) $$
The previous equation ...
- 105
0
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1
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2k
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Critical density as a function of scale factor
I am trying to do some cosmology problems. In an exercise given by my teacher he wrote the following:
$$
\Omega_m(a) = \frac{\rho_M(a)}{\rho_{crit}(a)} = \frac{\rho_{M,0}/a^3}{\rho_{crit}(0)(H/H_0)^2}....
- 722
1
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1
answer
242
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Connection between the cosmological constant $\Lambda$ and the cutoff scale $\Lambda$
I'm trying to understand the connection between the $\Lambda$ from cosmology and the $\Lambda$ from QFT.
Cosmology: The cosmological constant enters the Einstein equations. In the special case of the ...
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