Wikipedia's article on black holes

In summary, objects in a gravitational field experience time dilation, which has been experimentally verified in the Scout rocket experiment of 1976. The time dilation increases near a black hole and from the perspective of an external observer, it appears to take an infinite amount of time for an object to approach the event horizon. This means that from the viewpoint of an outside observer, after a black hole has formed, no new matter will enter it. However, these outside observers are located far outside the strong gravitational field of the black hole and can still observe objects falling into the black hole.
  • #1
kernelpenguin
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Objects in a gravitational field experience a slowing down of time, called time dilation. This phenomenon has been verified experimentally in the Scout rocket experiment of 1976 [2] (http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/gratim.html). Near a black hole, the time dilation increases to a large degree. From the point of view of an external observer, it appears to take an infinite amount of time for an object to approach the event horizon, at which point it is infinitely red-shifted.

That's what Wikipedia said.

If, for an outside observer, it takes an infinite amount of time for matter to enter a black hole, does this mean that from the point of view of an outside observer, after a black hole has formed, no new matter will enter it?
 
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  • #2
Sure looks that way, doesn't it. But they can see a traffic jam right above the event horizon. They can distinguish earlier fallers from later ones and so on. BTW, these outside observers are WAY outside, out where the spacetime bending by the black hole is negligible.
 
  • #3


Yes, that is correct. From the perspective of an outside observer, it would appear that no new matter can enter the black hole once it has formed. This is due to the extreme time dilation near the event horizon, where time appears to slow down to the point of being almost frozen. This phenomenon is a result of the intense gravitational pull of the black hole, which causes a distortion in the fabric of space-time. However, from the perspective of the matter falling into the black hole, it would experience the process of entering the black hole relatively quickly. This is due to the fact that time dilation is relative and depends on the observer's frame of reference. Overall, the concept of time dilation near a black hole is a fascinating aspect of general relativity and has been confirmed through various experiments.
 

1. What is a black hole?

A black hole is a region in space with a gravitational pull so strong that even light cannot escape from it. It is formed when a massive star collapses in on itself.

2. How big can a black hole be?

Black holes can range in size from a few kilometers to billions of times the mass of our sun. The largest known black holes are called supermassive black holes, which can be found in the centers of galaxies.

3. How do black holes affect nearby objects?

The gravitational pull of a black hole can cause nearby objects to orbit around it, similar to how planets orbit the sun. If an object gets too close, it can be pulled into the black hole and will not be able to escape.

4. Can anything escape from a black hole?

Once something crosses the event horizon of a black hole, it cannot escape. This includes light, which is why black holes are invisible and appear as dark regions in space.

5. Can black holes be observed or studied?

While we cannot directly observe black holes, we can study their effects on nearby objects and detect their presence through the radiation they emit. Scientists also use mathematical models and simulations to better understand black holes and their behavior.

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