Jump to content
Science Forums

Recommended Posts

On 10/14/2020 at 12:47 PM, A-wal said:

(1) :  Nothing can be trapped in an event horizon, objects fall towards it at progressively slower rate from the perspective of a distant observer but they never reach the horizon so after the black hole dies those objects will still be there, so they obviously can't reach the event horizon from their own perspective either.

Time moves normally from the falling observer's perspective and there is a future time on their watch that corresponds with reaching the event horizon but that's also true for the distant observer who would also calculate the falling observer's watch showing the same time infinitely far in the future by their own watch at the point when the falling object reaches the horizon. The closer an object gets to the event horizon the more tidal force it will feel, which is the difference in the strength of gravity over that object. Other than that nothing unusual happens. This is exactly what a normally accelerating object feels, if the energy that's accelerating it were evenly spread over that object then the object would feel no G-force.

A figure of speech; what I mean by "trapped matter" is matter that is in the process of this prohibitive tidal force. And I'm not exactly sure what you mean by saying the objects will still be there; do you mean that they will be in the exact position they were in the instant before the death of the black hole? If so, would it appear otherwise to a distant observer due to the intense spacetime geodesics involved? Would the tidal forces the matter had been previously experiencing transfer into velocity upon the black hole's death? If so, approximately where would this velocity be directed in correspondence with the given matter's coordinates on the event horizon? Would the physical properties of the matter make any difference in said velocity? If so, how, and what specific difference would be present in each of these (mass, surface area for larger objects, etc.)?

Edited by Anchovyforestbane
Link to post
Share on other sites
12 hours ago, Anchovyforestbane said:

A figure of speech; what I mean by "trapped matter" is matter that is in the process of this prohibitive tidal force. And I'm not exactly sure what you mean by saying the objects will still be there; do you mean that they will be in the exact position they were in the instant before the death of the black hole? If so, would it appear otherwise to a distant observer due to the intense spacetime geodesics involved? Would the tidal forces the matter had been previously experiencing transfer into velocity upon the black hole's death? If so, approximately where would this velocity be directed in correspondence with the given matter's coordinates on the event horizon? Would the physical properties of the matter make any difference in said velocity? If so, how, and what specific difference would be present in each of these (mass, surface area for larger objects, etc.)?

I just meant any objects that fall towards a black hole will still be there after the black hole's gone, having never reached the event horizon despite continually falling towards it (at a progressively slower rate from the perspective of a distant observer as the falling object becomes increasingly time dilation and length contraction from the distant observer's perspective) regardless how long the black hole lives.

If two objects are on opposite sides of the black hole they'll be accelerated towards each other with the black hole between them pulling them towards each other faster and faster as the black hole shrinks and then dies before the two of them smash into each other at a potentially extremely high relative velocity but still under the speed of light in their own frames but anything under twice the speed of light from the frame of a distant observer because one could be moving away from the distant observer at any velocity under the speed of light with the other falling object moving towards the distant observer at any velocity under the speed of light.

Tidal force won't transfer to any net acceleration or drag, it's the difference in acceleration over different parts of the same object. The closer areas of the falling object are under a greater acceleration so pull on the further parts creating additional acceleration at the rear and drag at the front and causing stress on the falling object. Normally you can treat a falling object as one object because the difference in acceleration over the object is tiny but it's always there and in the case of a black hole it can be huge. In those cases you can think of the object as a series of separate objects held together by a force, so when the tidal force exceeds that binding force the objects separate.

Link to post
Share on other sites
4 hours ago, A-wal said:

I just meant any objects that fall towards a black hole will still be there after the black hole's gone, having never reached the event horizon despite continually falling towards it (at a progressively slower rate from the perspective of a distant observer as the falling object becomes increasingly time dilation and length contraction from the distant observer's perspective) regardless how long the black hole lives.

If two objects are on opposite sides of the black hole they'll be accelerated towards each other with the black hole between them pulling them towards each other faster and faster as the black hole shrinks and then dies before the two of them smash into each other at a potentially extremely high relative velocity but still under the speed of light in their own frames but anything under twice the speed of light from the frame of a distant observer because one could be moving away from the distant observer at any velocity under the speed of light with the other falling object moving towards the distant observer at any velocity under the speed of light.

Tidal force won't transfer to any net acceleration or drag, it's the difference in acceleration over different parts of the same object. The closer areas of the falling object are under a greater acceleration so pull on the further parts creating additional acceleration at the rear and drag at the front and causing stress on the falling object. Normally you can treat a falling object as one object because the difference in acceleration over the object is tiny but it's always there and in the case of a black hole it can be huge. In those cases you can think of the object as a series of separate objects held together by a force, so when the tidal force exceeds that binding force the objects separate.

What precisely is the relationship between the properties of the hypothetical matter and the velocity at which they collide after the black hole's death? Additionally, how would the spaghettification the matter would undergo near the event horizon effect this relationship and/or the matter involved?

Link to post
Share on other sites
1 hour ago, Anchovyforestbane said:

What precisely is the relationship between the properties of the hypothetical matter and the velocity at which they collide after the black hole's death? Additionally, how would the spaghettification the matter would undergo near the event horizon effect this relationship and/or the matter involved?

Well the stronger the object is the more tidal force it could take before it breaks apart so the closer it could get to the event horizon before that happens.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...