Tagged Questions
5
votes
3answers
108 views
Is it possible to have a singularity with zero mass?
A singularity, by the definition I know, is a point in space with infinite of a property such as density.
Density is Mass/Volume.
Since the volume of a singularity is 0, then the density will thus ...
0
votes
0answers
24 views
Why photons can't escape black hole? [duplicate]
Photons do not have (rest) mass. Then why are they attracted by the black hole? And is it possible that a photon crossing a black hole from a little distance could get accelerated due to the force?
4
votes
2answers
168 views
Does the Chandrasekhar Limit scale for a Black Hole?
No physicist/astrophysicist I; All I know about the Chandrasekhar limit is that it apparently limits the mass a star may survive, beyond which it degenerates to a neutron star, or a black-hole.
Does ...
1
vote
2answers
245 views
Why do photons add mass to a black hole?
Why do photons add mass to a black hole?
When photons are taken irreversibly into a black hole does the mass of the BH increase?
0
votes
1answer
59 views
Is mass of the parent star is equal to the mass of the born blackhole
I want to know whether mass of the black hole which has born from a star is similar to its parent star or not. whether the born black hole will have high or low mass comparing to its parent star. ...
2
votes
1answer
118 views
The role of dark matter in black holes and star formation
In my understanding, there exists a critical mass for which a star needs to be in order for it to collapse into a black hole. This also applies to a certain critical density of gas in order for stars ...
1
vote
1answer
216 views
The Strength Of A Black Hole
Does the gravitational strength of a black hole at its singularity change the more it pulls things into it?
2
votes
1answer
227 views
Mass of Milky Way Supermassive Black Hole
I am looking at data from Andrea Ghez (2005; ADS link) which states the mass of the supermassive black hole in the MW. Here's what I don't understand: She reports the value as $3.7 \times 10^6 ...
3
votes
1answer
387 views
What happens to a photon in a black hole?
Assume a photon enters the event horizon of a black hole. The gravity of the black hole will draw the photon into the singularity eventually. Doesn't the photon come to rest and therefore lose it's ...
1
vote
3answers
207 views
Formation of black holes
If stars start with a finite density and light can escape from them, how can they be compacted to form a mass with infinite density which light cannot escape? The black hole will have the same mass as ...
12
votes
3answers
3k views
How do we determine the mass of a black hole?
Since by definition we cannot observe black holes directly, how do astronomers determine the mass of a black hole?
What observational techniques are there that would allow us to determine a black ...
11
votes
4answers
875 views
Why does a black hole have a finite mass?
I mean besides the obvious "it has to have finite mass or it would suck up the universe." A singularity is a dimensionless point in space with infinite density, if I'm not mistaken. If something is ...
12
votes
3answers
1k views
If the universe were compressed into a super massive black hole, how big would it be?
I understand only a little of general relativity, but that's why I'm here! :)
Consider the hypothetical situation of some extra-terrestrial intelligence pushing all the mass in the universe, every ...
