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What is a black hole? Show more Show less
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Black holes are one of the most mysterious objects in the Universe. They consist of an immense amount of matter packed into a tiny volume, giving them enormous density and gravity. The gravitational pull is so high that not even light can escape, so they are invisible. These objects have puzzled astronomers and physicists for decades - what is a black hole and what do we know about them?

Properties of a black hole Show more Show less

The strange attributes of black holes have been a long studied question for scientists.
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The no-hair theorem

Despite their complications, no-hair theorem states that black holes can be described simplistically.

The Argument

Black holes are complicated objects: born at the death of a star, they have immense mass, infinite density, and infinite gravity, and warp the fabric of spacetime into a single dimension. Yet a theorem known as no-hair theorem states that all this complexity is hidden behind the event horizon and that on the outside black holes can be described with just three quantities. All information about the black hole and what has gone into it besides these three aspects is lost behind the event horizon and cannot be interpreted or measured.[1] No-hair theorem describes black holes by three attributes: mass, electric charge, and angular momentum. Mass is the amount of matter compacted in the center of the black hole. Electric charge is the overall electromagnetic charge that the black hole possesses. Angular momentum is which direction, and how forcefully, the black hole is spinning. Regardless of how they form or what matter they have enveloped, black holes that have the same values for these three numbers are indistinguishable.[2]

Counter arguments

Some black holes do have hair. The no-hair theorem only applies to isolated black holes that are not interacting with matter. When interacting with matter other properties of black holes are visible, and this is the case with most black holes. In addition, black holes do have more complexity within the event horizon. Just because it isn't visible to an outside observer does not mean that it isn't there.

Proponents

Premises

[P1] Almost no information can escape the event horizon of a black hole. [P2] Outside the event horizon, only three qualities of a black hole can be observed. [P3] These qualities are mass, electric charge, and angular momentum.

Rejecting the premises

References

  1. https://arstechnica.com/science/2019/09/physicists-hear-the-ringing-of-a-baby-black-hole-for-the-very-first-time/
  2. https://physics.aps.org/articles/v8/34
This page was last edited on Wednesday, 26 Aug 2020 at 01:57 UTC

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