Observable Universe and Black Holes

In summary: We are pretty confident objects, like galaxies, that are outside the observable universe are causally disconnected from the observable universe. Or, in other words their light, gravity, etc., have no effect on bodies within the observable universe. We are not causally disconnected from black holes within the observable universe. We still experience the effects of gravity and charges generated by black holes.In summary, the curvature of spacetime is intrinsic to space and exists even outside of our observable universe. Objects that are outside the observable universe are causally disconnected from the observable universe.
  • #1
sefer
1
0
Hi, my first post here!

Galaxies outside the observable universe (that we can't see their light) can affect us with their gravity?
If the answer is no, we can say that gravity information travels at the speed of light.
So, in a black hole how gravity information from an object inside, escapes the event horizon?
An object inside a black hole is also outside our observable universe.
I know that in general relativity mass of a black hole is responsible for the curvature of spacetime, but where this curvature begins in our universe? Does it begin from the Event Horizon limit? Can we say the event horizon itself carries all the gravity information of a black hole?

I can't figure it out, I have it, all in a mess inside my mind
 
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  • #2
Thats...tough to answer properly. Consider that gravitation is, as far as we know, infinite in reach. Very early in the universe it is believed that the universe was compressed to a very high degree. The matter and energy here was very close together, so it would have easily had time for its gravity to affect our area. However, inflation and expansion have pushed some of that matter and energy outside of our view for the future. BUT, this process hasn't happened instantly, it has taken time, and the gravity, while having weakened, should still be affecting us at least a tiny amount. (REALLY tiny. So tiny that expansion overwhelmingly dominates gravitation between us)

Similarly, infalling objects do not fall in instantly, they take time. Plus, from our perspective they don't actually ever fall in thanks to time dilation! For practically all intents and purposes their gravity simply adds to the black hole.
I know that in general relativity mass of a black hole is responsible for the curvature of spacetime, but where this curvature begins in our universe? Does it begin from the Event Horizon limit? Can we say the event horizon itself carries all the gravity information of a black hole?

This curvature is not something you can say "starts" or "ends" somewhere. It simply exists. It is an intrinsic part of spacetime. I don't think I can explain it very well.
 
  • #3
We are pretty confident objects, like galaxies, that are outside the observable universe are causally disconnected from the observable universe. Or, in other words their light, gravity, etc., have no effect on bodies within the observable universe. We are not causally disconnected from black holes within the observable universe. We still experience the effects of gravity and charges generated by black holes.
 
  • #4
Chronos said:
We are pretty confident objects, like galaxies, that are outside the observable universe are causally disconnected from the observable universe. Or, in other words their light, gravity, etc., have no effect on bodies within the observable universe. We are not causally disconnected from black holes within the observable universe. We still experience the effects of gravity and charges generated by black holes.

Certainly we wouldn't be affected by changes in them since they moved out of our observable universe, but in the past was there ever a certain point where their influence on us through gravity simply disappeared?
 
  • #5
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I can understand your confusion and curiosity about the relationship between the observable universe and black holes. To answer your questions, I'd like to start by clarifying that the observable universe is the portion of the entire universe that we can observe from Earth. It is limited by the distance that light has traveled since the beginning of the universe, which is estimated to be about 13.8 billion light-years. Beyond this distance, the light from objects has not reached us yet, making them unobservable to us.

Now, to address your question about the effects of gravity from galaxies outside the observable universe, the answer is yes. According to Einstein's theory of general relativity, gravity is a result of the curvature of spacetime caused by massive objects. This curvature extends beyond the observable universe, so the gravity from these distant objects can still affect us.

In regards to black holes, it is true that the gravity information from an object inside a black hole cannot escape the event horizon. This is because the escape velocity at the event horizon is greater than the speed of light, making it impossible for any information to escape. This is why black holes are often referred to as "information sinks."

As for where the curvature of spacetime begins in our universe, it is believed to originate from the singularity at the center of a black hole. This is the point where the mass of the black hole is concentrated, resulting in an extreme curvature of spacetime. However, the event horizon itself does not carry all the gravity information of a black hole. The entire black hole, including its singularity and event horizon, contributes to the curvature of spacetime.

I hope this helps to clear up some of your confusion. The study of black holes and their effects on the universe is a complex and ongoing area of research, and there is still much we have yet to fully understand. But through continued scientific exploration and observation, we can continue to unravel the mysteries of our vast and fascinating universe.
 

1. What is the Observable Universe?

The Observable Universe is the part of the universe that we are able to see and detect using telescopes and other instruments. It is estimated to be approximately 93 billion light years in diameter.

2. How do we measure the size of the Observable Universe?

The size of the Observable Universe is estimated using the speed of light and the age of the universe. Since light travels at a finite speed, we can only see objects that are within a certain distance from us, which is known as the observable distance. This distance is then multiplied by 2 to account for the observable universe's diameter.

3. What are black holes?

Black holes are regions in space where the gravitational pull is so strong that nothing, including light, can escape. They are formed when a massive star dies and collapses in on itself, creating a singularity with infinite density.

4. How do we detect black holes?

Black holes cannot be directly observed since no light can escape from them. However, we can detect their presence through their effects on surrounding matter. For example, we can observe the gravitational effects of a black hole on nearby stars and gas clouds.

5. Can anything escape from a black hole?

According to current theories, nothing can escape from a black hole once it has passed the event horizon, which is the point of no return. However, there are some theories that suggest information may be able to escape from a black hole, but this is still a topic of debate among scientists.

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