Question

In: Physics

Possible Duplicate: Black hole formation as seen by a distant observer Given that matter can never...

Possible Duplicate:
Black hole formation as seen by a distant observer

Given that matter can never cross the event horizon of a black hole (from an external observer point of view), if a black hole is "fed" with a large amount of matter then the new matter will eventually become extremely compressed, and presumably would be compressed below its Schwarzchild radius.

Would secondary black holes eventually form near the original black hole?

As an alternative one could also imagine that the combined mass of the original black hole and the new mass around the event horizon becomes contained within the Schwarzchild radius of both masses, and so a new event horizon forms, "swallowing" the new mass around the edge of the original black hole.

This mechanism would allow black holes to swallow mass in a finite time.
Would this contradict GR predictions?

Solutions

Expert Solution

Of course that black holes can swallow and do swallow additional matter and increase their mass in finite time, whatever reasonable coordinates we choose.

Yes, the Schwarzschild radius for the combined system smaller black hole + extra matter ("food") is larger than it is for the original smaller black hole which means that it's enough for the new matter to cross a critical surface that is outside the original event horizon of the smaller black hole. This occurs in finite time, even from the external observer's viewpoint, and the black hole simply grows in size.

It's a routine process we observe at many places. For example, the black hole at the galactic center devours new matter all the time.

Incidentally, there can't exist any "concentric pairs of black holes" solutions to the 3+1-dimensional general relativity. Once we know that it's the empty Schwarzschild metric up to the event horizon (from outside), then it is the black hole and there's no way for the metric to "unbecome" a black hole again. Everything that is inside the event horizon is, by definition, causally disconnected from infinity


Related Solutions

Black Hole has such a huge gravity, impacting space and matter in its vicinity the way...
Black Hole has such a huge gravity, impacting space and matter in its vicinity the way that velocity reaches infinity, thus the time is close to zero, why or why not? include a short description of the Black Hole (how it forms, its characteristics after it forms and the definition of the Event Horizon. Perhaps you can also come up with a live example, which would help to explain the processes happening around the black hole.
Multiple choice: The presence of a black hole in a galaxy core can be inferred from...
Multiple choice: The presence of a black hole in a galaxy core can be inferred from (a) the total mass of the galaxy; (b) the speeds of stars near the core; (c) the color of the galaxy; (d) the distance of the galaxy from the Milky Way Galaxy; or (e) the diminished brightness of starlight in the galaxy core, relative to surrounding areas. Multiple choice: Which one of the following statements about black holes is false? (a) Inside a black...
Once you have detected the possible presence of a black hole, what data do you need...
Once you have detected the possible presence of a black hole, what data do you need to prove that it is indeed a black hole and not a very massive star cluster?
What are the different death scenarios for a black hole? I know they can evaporate through...
What are the different death scenarios for a black hole? I know they can evaporate through Hawking radiation - but is there any other way? What if you just kept shoveling more and more mass and energy into the black hole?
Question No 1: The subject ‘economics’ is growing day-by-day and its subject matter can never be...
Question No 1: The subject ‘economics’ is growing day-by-day and its subject matter can never be rigid. In other words, the definitions of economics must not be rigid. Because of modern research, many new areas of economics are being explored. But, the definitions of economics are still revolving around the four ancient definitions. In this context, answer the following. a) Critically evaluate the four definitions of economics from the modern perspective. [Answer in 240 – 320 words] b) According to...
Please explain what Protesting and the Black Lives matter can deal with Social Learning and Strain...
Please explain what Protesting and the Black Lives matter can deal with Social Learning and Strain Theories
Given that virtually nothing can escape from black holes, explain how black holes are important in...
Given that virtually nothing can escape from black holes, explain how black holes are important in producing the enormous luminosities observed from the centers of some galaxies.
Is it possible that space has density, i.e., can a given space of 1 cm have...
Is it possible that space has density, i.e., can a given space of 1 cm have multiple 1 cm compressed into its 1 cm self? TO GIVE AN INSIGHT INTO THIS QUESTION LET ME EXPLAIN WHAT I REALLY MEAN. So we all know the displacement route between 2 points in 2-D space is the straight line between the 2 points. Now in case of its 3-D self, the line joining the 2 points isn't the shortest route between them. So...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT