Spaceship accelerating inside a Black Hole

In summary, the observer at the EH will see all movement forward in time as movement toward the center. From the EH on inward, all timelines (all futures) progress toward the center. Nothing can accelerate in the direction opposite to the singularity. Objects will take an infinite amount of time to reach the singularity, no matter how fast they are accelerating.
  • #1
quasar987
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LURCH said:
5)More revealing to say that the observer at the EH will see all movement forward in time as movement toward the center. From the EH on inward, all timelines (all futures) progress toward the center.
Does this implies that a spaceship, inside a black hole, accelerating in the direction OPPOSITE to the singularity would actually accelerate TOWARDS the singularity? Or does it simply mean that no matter how fast a speed he reaches through his acceleration, he would never get to a speed fast enough to stop his falling towards the center?

Also, is it true that an object inside a black hole will never quite reach the center? That would make a lot of sense for a black hole consisting of an infinitely dense star. However, I think some (most?) people on this forum would tend to believe the star doesn't collapse infinitely on itself but rather has a minimum size (something I would intuitively tend to believe too). In this scenario, it would seem that matter falling in a black hole would be able to reach the center after some time. Correct?

Lastly, if the center of the BH is NOT an infinitely dense star but rather has some definite volume, would it still be called a 'singularity' or is the word stritcly reserved for points at which the curvature of space-time is infinite?
 
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  • #2
strange

I thought that black holes were a type of worm hole with no real center just a long tube.
 
  • #3
The term "singularity" is indeed reserved for a mass with no dimensions, occupying a single point.

I am one of those who do not believe BH's have a singularity at the center, and your statement about time-dilation making it take forever to reach the center is precisely the reason why. If time dilation makes the final moment of infall take forever, then this also applies the final moment of collapse for the original mass. So theoretically, niether the original mass nor any infalling object would ever reach the center.
 
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  • #4
I was under the impression that pretty much no scientists though there was a singularity in a black hole anymore? I thought the only possible singularity anyone talked about seriously now was pre-big bang? But maybe I'm wrong.
 
  • #5
LURCH said:
The term "singularity" is indeed reserved for a mass with no dimensions, occupying a single point.
Since when? An infinite 2-dimentional line of mass-energy (e.g. a beam of light with no width) has a 2d-singularity. It doesn't even have an event horizon. I guess that's called a naked singularity.

Does this implies that a spaceship, inside a black hole, accelerating in the direction OPPOSITE to the singularity would actually accelerate TOWARDS the singularity?
Nothing can accelerate in the direction opposite to the singularity.

And I don't believe that anything can reach the singularity since it would take an infinite amount of time to do so. I think the distance from a point outside the BH to the singularity is infinite - Don't quote me though since I'm not really into black holes.

Pete
 
  • #6
quasar987 said:
Does this implies that a spaceship, inside a black hole, accelerating in the direction OPPOSITE to the singularity would actually accelerate TOWARDS the singularity? Or does it simply mean that no matter how fast a speed he reaches through his acceleration, he would never get to a speed fast enough to stop his falling towards the center?

Acceleration, in whatever direction, will only mean that it reaches the singularity sooner. The way to survive longest is to stay in free fall. I'm not sure that is makes sense to talk of accelerating in the direction OPPOSITE to the singularity as this direction is now timelike - how do you accelerate backwards in time? :confused:

quasar987 said:
Also, is it true that an object inside a black hole will never quite reach the center? That would make a lot of sense for a black hole consisting of an infinitely dense star.
Using Schwarzschild coordinates (the coordinate system of an outside observer) an object takes an infinite amount of time to reach the event horizon and even longer:rolleyes: to reach the singularity. However from the point of view of the infalling obect it crosses the event horizon and reaches the singularity within a finite (and for typical black holes, fairly short) time.
quasar987 said:
However, I think some (most?) people on this forum would tend to believe the star doesn't collapse infinitely on itself but rather has a minimum size (something I would intuitively tend to believe too).
Quantum theory suggests that there is some limit to how small the collapsing star can become. However we don't have a quantum theory of gravity yet so its hard to know. My guess is that black holes will turn out not to exist (see www.chronon.org/articles/blackholes.html)
gonzo said:
I was under the impression that pretty much no scientists though there was a singularity in a black hole anymore? I thought the only possible singularity anyone talked about seriously now was pre-big bang? But maybe I'm wrong.
I would think that full quantum gravity would also eliminate the big-bang singularity
 
  • #7
Although no mass reaches the center in finite time, the gravitational effects of the mass, as seen from outside the event horizon, are indistinguishable from the gravitational effects of a point singularity. If you could magically teleport to the center of a black hole, without waiting forever to get there, you would see empty space and null gravity. But, without magic, there's no way to reach the center of mass ahead of the mass that's already gotten "sufficiently close" to the event horizon.
If you free-fall to the center, you get there in finite time in your worldline, but the mass needed to form the actual singularity gets there ahead of you (or at the same time, at the end of time).
 
  • #8
As an interesting sidenote:

I have even seen an article explaining how, within the event Horizon, even centrifugal force works in reverse. A traveler attempting to keep his distance from the center of black hole by accelerating laterally and trying to "orbit" the center will find that, the faster he orbits, the more force he generates toward the center! I found this completely mind blowing.
 

1. How can a spaceship accelerate inside a black hole?

It is a common misconception that objects cannot accelerate inside a black hole. In fact, the intense gravitational pull of a black hole can cause objects, including spaceships, to accelerate at incredible speeds. This is due to the distortion of space and time near the black hole's event horizon.

2. Will the spaceship be crushed by the intense gravity inside a black hole?

As the spaceship approaches the black hole's event horizon, the gravitational pull will become stronger and stronger. However, the spaceship's own gravitational pull will also increase, keeping it intact. It is only when the spaceship reaches the singularity at the center of the black hole that it will be crushed.

3. Can a spaceship escape from a black hole once it has entered?

If a spaceship has already crossed the event horizon and entered the black hole, it is impossible for it to escape. The intense gravitational pull will continue to increase, making it impossible for the spaceship to accelerate to the speed needed to escape the black hole's pull.

4. Will time pass differently for the spaceship accelerating inside a black hole?

Yes, time dilation is a well-known effect near black holes. As the spaceship accelerates towards the black hole's event horizon, time will appear to slow down for the passengers on board. This is due to the intense gravitational pull and the distortion of space and time near the black hole.

5. What would happen to the spaceship's crew if they were to enter a black hole?

As the spaceship approaches the black hole's event horizon, the crew will experience extreme tidal forces, which can cause them to stretch and distort. Once the spaceship reaches the singularity at the center of the black hole, the crew will be crushed by the immense gravitational pull. However, this is all theoretical as no human-made spaceship has ever entered a black hole.

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