All Questions
26
questions
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2
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289
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Understanding the Singularity of Black Holes [duplicate]
Could someone please explain how we know the singularity has an infinite density and zero size/volume? From reading around online black holes have a defined radius (the event horizon) but this isn't ...
- 565
1
vote
2
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596
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A black hole made of ordinary water?
Years ago I read a book about black holes. It said it is theoretically possible to make a black hole from ordinary-density materials, like tap water. It would take a lot -- about the size of a galaxy ...
- 265
1
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0
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117
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Is it correct that a sphere of water the size of Venus's orbit would instantly be a black hole? [duplicate]
Let's say I have a genie and wish for a sphere of water at earth density the size of Venus' orbit - would it be instantly indistinguishable from a supermassive black hole due to the schwarzchild ...
- 11
1
vote
3
answers
2k
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Why does General Relativity predict that singularities are infinitely dense?
From my understanding of general relativity, energy curves spacetime to produce an effect that we call gravity. The greater the concentration of energy, the greater the curvature and hence the greater ...
1
vote
1
answer
113
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Definition of density of black holes
For a blackhole of mass $M$, radius $R$ and Schwarzschild radius $R^*$ (where $R<R^*$), its density $\rho$ is defined as $$\rho=\frac{M}{(R^*)^3}.$$
One reason I read for using the Schwarzschild ...
- 4,235
1
vote
1
answer
145
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Formation of Black Hole
Black holes are formed when energy is put in a small region of space, I was wondering if there is a threshold to how much energy should I add in a certain volume of space to get a black hole, I read ...
- 31
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3
answers
227
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Why is an event horizon dependent on density?
It’s frequently stated in Astronomy documentaries that you could replace the sun with a black hole of equivalent mass and the orbital mechanics will continue as normal. This works fine in dispelling ...
- 113
13
votes
2
answers
850
views
Can a Black Hole become a normal mass again?
It is well known how Black hole forms. But once it is formed are there any circumstances which can lead a black hole to becoming a normal mass again?
0
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0
answers
36
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Black Hole Mass Density Ratio [duplicate]
(1) The density of water increases as one approaches the bottom of the sea.
(2) The density of neutron stars also increases from crust to core.
Black holes with greater mass have a larger radius and ...
- 127
0
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0
answers
48
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What is the energy density of a 10 solar mass black hole as if the mass is distributed throughout the volume of the event horizon.? [duplicate]
I am looking for the average mass/energy density contained in the black hole per cubic centimeter. As if the singularity did not exist.
2
votes
4
answers
308
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Is there a limit to the amount of mass we can concentrate in a region of space?
Black holes are solutions to Einstein's Field Equations. Black holes contain a singularity hidden from the outer universe. As I understand, these singularities are infinitesimal and contain a very ...
- 1,266
1
vote
1
answer
151
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Black hole and its density
I'm an amateur to astrophysics but I'm slowly teaching myself things and I have these three doubts.
How does more compression relate to a stronger gravitational pull. Like, when we say that a black ...
- 131
3
votes
1
answer
4k
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Black Hole Surface Area-Mass Equation
Lets suppose we have a BH with mass $M$ and surface area $A$.
From the Schwarzschild raidus we can say that the Area of the BH is proportional to its mass
$$A=4\pi r^2=\frac {16 \pi G^2M^2} {c^4}$$ ...
- 3,122
1
vote
1
answer
97
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Where is mass density information of a Black Hole?
Have read that all the information of a black hole is contained on the Event Horizon. Does that include mass density of interior as a function of position? The shape of an event horizon depends on the ...
- 2,728
0
votes
1
answer
192
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Properties of singularity
I read that singularity is point in space where is infinite gravitational force caused by collapsing something very big into something very small.
How can something with certain mass (star few ...
- 117