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pawprint
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On approach to a simple (non-rotating, uncharged) singularity, does g increase asymptotically near...
a) the singularity,
b) its event horizon,
or c) no?
a) the singularity,
b) its event horizon,
or c) no?
Paul.Dent said:Here is the $64000 question: At what point does the Black Hole's event horizon increase its radius?
Any opinions, arguments or math about this, anyone?
Paul.Dent said:I can't accept that the event horizon is not "a point in spacetime" We can and do assign coordinates to it, so it must be! However, I do have some grave doubts about its nature.
Here is one issue I am struggling to understand:
I think I am right in saying the gravity gradient at the event horizon is finite and gets smaller, the larger the Black Hole is. So make it large enought, and matter falling in does not necessarily get torn apart while still on the outside, especially if heading in in a straight line plumb dead center. So consider that situation. Now, just before the matter enters, the event horizon's radius is given by thre mass already on the inside; and just after enters, the Black Hole's mass and its radius must have increased.
Here is the $64000 question: At what point does the Black Hole's event horizon increase its radius? Doe sit come out to meet the falling in mass, like a big snake's mouth opening up" Does that mean the Black Hole gets a bulge on side, that subsides as the matter plummets towards the cental singulaity? I have big problem with the latter, because that implies we a getting information on the outside about events on the inside. I have other reasons to want to believe that a Back Hole can only accrete mass in a sphercially synnetric way. At least in a cylindrically symmetric way, if there is angular momentum invloived. But preferably, only in a spherically symmetric way when there is no angular momentum involved. In the latter case, the matter would cover the event horizon uniformly and then continue its chute towards the central singularity as a uniform sphere of collapsing radius.
Any opinions, arguments or math about this, anyone?
Paul.Dent said:Here is the $64000 question: At what point does the Black Hole's event horizon increase its radius? Doe sit come out to meet the falling in mass, like a big snake's mouth opening up" Does that mean the Black Hole gets a bulge on side, that subsides as the matter plummets towards the cental singulaity? I have big problem with the latter, because that implies we a getting information on the outside about events on the inside. I have other reasons to want to believe that a Back Hole can only accrete mass in a sphercially synnetric way. At least in a cylindrically symmetric way, if there is angular momentum invloived. But preferably, only in a spherically symmetric way when there is no angular momentum involved. In the latter case, the matter would cover the event horizon uniformly and then continue its chute towards the central singularity as a uniform sphere of collapsing radius.
Any opinions, arguments or math about this, anyone?
pervect said:[itex]r_s[/itex] is the Schwarzschld radius, [itex] r_s= G m / c^2 [/itex]
elfmotat said:You mean [itex] r_s= 2G m / c^2 [/itex], right?
Paul.Dent said:Here is the $64000 question: At what point does the Black Hole's event horizon increase its radius?
Poisson said:It is a remarkable property of the event horizon that the entire history of the spacetime before its position can be determined
I do not think that is correct.Nabeshin said:If we imagine a hole of mass M, and throwing in some small mass dm, the event horizon smoothly expands from its radius at r=2M to r=2(M+dm) as the mass falls in.
Passionflower said:I do not think that is correct.
The total mass will be slightly less than M+dm.
The value of g, or the acceleration due to gravity, near a black hole is extremely high. It can reach up to billions of times stronger than the gravity on Earth.
The value of g near a black hole is significantly stronger than Earth's gravity. This is because the mass of a black hole is so concentrated in a small area, creating an intense gravitational pull.
The gravitational pull near a black hole is so strong that even light, which is the fastest thing in the universe, cannot escape. This is why black holes are often referred to as "light traps."
Yes, the value of g near a black hole changes depending on the distance from the black hole. The closer an object is to the black hole, the stronger the gravitational pull.
According to Einstein's theory of relativity, time near a black hole is affected by the intense gravitational pull. Time appears to slow down near a black hole, as observed by an outside observer. This is due to the effects of gravity on space-time.