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Results tagged with black-hole
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user 34155
Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.
3
votes
2
answers
200
views
Do all black holes, including stellar-mass ones, rotate at nearly the speed of light? Also, ...
From what I understand, astrophysicists have known for almost a decade that supermassive black holes seem to spin at incredible velocities; nearly the speed of light... In fact, some of the outer par …
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3
votes
1
answer
115
views
Could the revolution of super-massive black holes around each other create a pulsar-array gr...
Some commentators on the recently-observed very-long-wavelength gravitational wave signal involving pulsars, like Dr. Becky Smethurst, have implied that it might not be merging supermassive black hole …
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1
vote
2
answers
562
views
Why is a black hole's Hawking radiation temperature inversely proportional to its mass/size?
As a black hole shrinks in volume and mass, shouldn't its temperature get lower? Shouldn't it evaporate more slowly?
Naively, (very naively), I think that with a smaller surface area (as per its even …
- 5,585
7
votes
1
answer
149
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What exactly is a 'gravastar'? How is it different from a 'regular' black hole?
The Wikipedia article on gravastar says that it has a 'regular' black hole metric (Schwarzschild, I presume?) on the outside, but a de Sitter metric on the inside....
What exactly does that mean?
Don' …
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-2
votes
1
answer
846
views
What does 's' or 'ds' or $ds^2$ mean in the Schwarzschild equation(s)? [closed]
And:
These are from Wikipedia on Schwarzschild metric, Derivation of the Schwarzschild metric and the last is from Science Direct, Schwarzschild metric.
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3
votes
1
answer
220
views
How, precisely, do radio astronomers detect (and record) the phases of waves for interferome...
Interferometry is always in the news, and at radio frequencies it has been for a long time...
The popular press always talks about directly 'interfering' two waves as they come in, but can they tell t …
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2
votes
1
answer
58
views
What is the relation between size (radius) of an astronomical object and the speed of oscill...
From the year-end issue of New Scientist Magazine (Dec. 18-31,2021):
Astronomy:
'Space Cow' explosion was probably a failed supernova'
Page 10: 'They found that the strength of this radiation oscill …
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12
votes
3
answers
2k
views
Why did astronomers believe most or all stellar black holes had masses no greater than 15 so...
The so-called 'mass gaps' for black holes, according to theoretical models, are between 2-5 solar masses and 50 to 150 solar masses. (Actually, I have read that there is no good theoretical reason fo …
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1
vote
0
answers
57
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Does the (relative) distance of the photon sphere from the center of a black hole vary accor...
I know that the photon circle or photon sphere is located at around 1.5 times the radius of the Schwarzschild event horizon, but wouldn't it be comparatively further out for smaller black holes?
After …
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2
votes
2
answers
161
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Does the density of a black hole decrease after releasing a large amount of Hawking radiation?
Is is true that the smaller a 'regular', stellar-mass black hole is, the denser it is inside of its event horizon? After all, if you look up (or calculate) the Schwarzschild radii of the Sun and the E …
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4
votes
2
answers
639
views
How can a black hole merger create a black hole with an event horizon surface area larger th...
Many popular and professional science sites said something about Stephen Hawking's black hole area theorem being proven observationally, finally, not just mathematically, to 95% confidence. For exampl …
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2
votes
3
answers
732
views
How can Kerr black holes have a 'speed limit' to how fast they can spin?
Obviously, the speed of light is a presumed limit, at least for 'physical' objects moving 'within' ('through'?) spacetime, but...
In recent news some scientists believe they have figured out the appro …
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6
votes
1
answer
552
views
What do the symbols signify in Dr. Becky Smethurst's radiation pressure equation for black h...
In her most recent video, "An ULTRAMASSIVE black hole has been discovered in a BRAND NEW way!", as well as a previous video, "How massive can black holes get?", Dr. Becky Smethurst shows an equation …
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0
votes
0
answers
26
views
Is the hypothetical '(Don) Page curve' of evaporating black holes equal in time, so to speak...
I have heard that Hawking radiation is slow at first, but rapidly increases when the black hole becomes much smaller... (I forget the formula...)
Does that mean that the second half of Page's curve, w …
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12
votes
4
answers
6k
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How can a black hole have a charge, or be charged?
So-called 'hairless' black holes (no-hair theory, or theorem?) , which is what real black holes are, can be described by just three characteristics: Mass, spin, and charge.
It is easy enough to contem …
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