All Questions
Tagged with black-holes cosmology
215
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Schwarzschild Radius of the Universe
According to the Wiki on the $R_s$, the $R_s$ of the observable universe is 13.7BLY.
https://en.wikipedia.org/wiki/Schwarzschild_radius
(The observable universe's mass has a Schwarzschild radius of ...
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Black Hole Formation -- How Can an Event Horizon be Observed to Grow? [duplicate]
This is a question about black hole formation. To be clear, I’m not suggesting that black holes don’t form. It’s that I’m having trouble with the accepted explanation so there’s a flaw in my logic ...
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5
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How can micro black holes exist?
How could a micro black hole exist, when there is so little matter to produce the intense gravitational force required to crush matter to that extent? It takes the collapse of a supermassive star to ...
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Calculating Gaussian Curvature for metric
I am trying to calculate Gaussian curvature of an optical metric
$$
d \sigma^2=\frac{r\left(\omega_{\infty}^2-\omega_e^2\right)+2 m \omega_e^2}{(r-2 m) \omega_{\infty}^2}\left(\frac{d r^2}{1-\frac{2 m}...
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Does the Schwarszchild solution require the cosmological constant to stop it from expanding?
When Einstein developed his field equations for general relativity, he attempted to apply them to the entire universe. He found the universe had to expand, which at the time was believed not to be the ...
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Probability of a primordial black hole absorbing background radiation?
I'm thinking of the early universe when there was a lot of energetic radiation around. A primordial black hole (PBH) that would be about to evaporate completely about now, would have an initial mass ...
- 133k
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2
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Test of the primordial black hole solution to dark matter
One of the ideas that might solve some of the dark matter problem are the existence of many small black holes. There is evidence, in principle, for the existence of these small black holes via the ...
- 133k
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Trapping Hawking radiation in black holes?
I was reading this writing (https://davidwoolsey.com/AttO/AttO_blog/Entries/2020/7/13_Black_Holes_and_Transverse_Tidal_Effects%2C_a_revised_essay_on_some_thoughts.html) about considering tidal effects ...
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5
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Could primordial black holes have been supermassive?
Usually when primordial black holes are mentioned, they are imagined to be tiny. Could they have been supermassive? This would explain the existence of quasars in early universe.
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8
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1
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We say the big bang (initial singularity) didn't happen at a point, but is it the same with the singularity of a black hole?
I have read this question:
The simple answer is that no, the Big Bang did not happen at a point. Instead, it happened everywhere in the universe at the same time. Consequences of this include
The ...
CommunityBot
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Angular momentum, black holes and up-tunneling events in the vacuum
To give some context on the matter, I found these interesting articles (https://arxiv.org/abs/2007.11428 & https://arxiv.org/abs/2003.04927) where the authors analyzed, among other things, the ...
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Is Poplawski's "Cosmology with torsion" a "variable speed of light" cosmology?
In his 2010 paper "Cosmology with torsion", Poplawski mentions that, in the hypothesized formation of a new temporally-local universe within a black hole, its "expansion is not visible for observers ...
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-1
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1
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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?
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What is the difference between the cosmological and the black hole horizons in thermodynamics?
I want to know the different thermal behaviors between cosmological and black hole horizons, such as temperature, entropy and so on.
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Given that matter cannot escape a black hole, how did the big bang produce the universe we see today?
Extrapolation of the expansion of the Universe backwards in time using general relativity yields an infinite density and temperature at a finite time in the past.
If the matter contained within our ...
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