Exploring the Physics of a Black Hole's Event Horizon

In summary, the conversation discussed the concept of the event horizon of a black hole and its relationship to the curvature of space and the speed of light. It was noted that the event horizon does not have infinite curvature and that while it can appear to move at the speed of light, this is a local description and does not mean that objects are actually moving at the speed of light. Additionally, the statement about infinite energy needed to accelerate mass to the speed of light was clarified to be misleading and better described as the impossibility of describing something with mass traveling at the speed of light in a coherent way. The conversation concluded with the acknowledgement that all statements made were incorrect and the thread was closed.
  • #1
Steve1954
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At the event horizon of a black hole, the curvature of space is infinite. Matter falling in therefore becomes accelerated to the speed of light. General relativity says infinite energy need to accelerate mass to the speed of light. Comments please
 
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  • #2
Steve1954 said:
At the event horizon of a black hole, the curvature of space is infinite.
No it is not.

Steve1954 said:
Matter falling in therefore becomes accelerated to the speed of light.
No it is not. You need to be careful with what you mean by this. The event horizon locally moves at the speed of light, but this is because it is a null surface. It is the event horizon that locally moves at the speed of light relative to all observers. Any observers will have a relative speed below the speed of light.
 
  • #3
Steve1954 said:
Comments please

OK, here's one. Not a single thing you said was correct.

Here's another one. Posting a parade of incorrect statements is an inefficient way to learn.
 
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  • #4
Steve1954 said:
At the event horizon of a black hole, the curvature of space is infinite.
As noted by Orodruin, no it is not. Curvature goes to infinity at the singularity, not the event horizon.
Steve1954 said:
Matter falling in therefore becomes accelerated to the speed of light.
This isn't correct. The event horizon is an outgoing null surface, so a local description of a horizon crossing is that the horizon crosses you at the speed of light. But this doesn't mean you are doing the speed of light anymore than the fact that light passes you at the speed of light means you are doing the speed of light.

"Speed" in curved spacetime is not simple. Our everyday intuitive notions of it generally rely on assumptions that are spectacularly invalid near black holes.
Steve1954 said:
General relativity says infinite energy need to accelerate mass to the speed of light.
Although you see this in a lot of popsci sources, it's quite misleading phrased this way. It's better to say that it's impossible to describe something with mass traveling at the speed of light in a coherent way. The "infinite energy" comes from trying to apply the formula for kinetic energy of a massive body to a situation where it is not valid.
 
  • #5
Steve1954 said:
General relativity says infinite energy need to accelerate mass to the speed of light. Comments please
You seem to mean proper acceleration here, e.g. acceleration by a rocket. But in the context you are mentioning objects are passing the event horizon in free fall.
 
  • #6
Steve1954 said:
Comments please

As has already been pointed out, every statement you made is incorrect. And you didn't ask a question, so there's no point in continuing this thread.

Thread closed.
 

FAQ: Exploring the Physics of a Black Hole's Event Horizon

1. What is the event horizon of a black hole?

The event horizon of a black hole is the boundary surrounding the black hole from which nothing, including light, can escape. It is the point of no return for anything that gets too close to a black hole.

2. How is the event horizon of a black hole measured?

The event horizon of a black hole is measured by its Schwarzschild radius, which is directly proportional to its mass. The larger the mass of the black hole, the larger its event horizon will be.

3. What happens to time at the event horizon of a black hole?

According to Einstein's theory of relativity, time slows down near objects with a strong gravitational pull. At the event horizon of a black hole, time appears to stand still for an outside observer, while for an object falling into the black hole, time seems to speed up.

4. Can anything survive passing through the event horizon of a black hole?

No, anything that passes through the event horizon of a black hole will be pulled into the singularity at its center, where the gravitational pull is infinitely strong. This is known as the "spaghettification" effect, where objects are stretched and torn apart by the strong gravitational forces.

5. How does the event horizon of a black hole affect the surrounding space?

The event horizon of a black hole has a strong influence on the surrounding space. It can bend and distort light, creating the effect of gravitational lensing. It also has a significant impact on the movement of objects and even the structure of space-time itself.

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