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Author Topic: Can I Be Rescued From The Event Horizion Of A Black Hole ?  (Read 6330 times)

Offline neilep

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Dearest Luffly Black Holeologists,

As a sheepy I of course own my very own black hole !..it's pert and neat and has a luffley rim.


As ewe all well know, Black holes are made from liquorice in Pontefract thusly,


Pontefract Black Holes Earlier Today

Hmmm..being delivered next Tuesday...

As ewe also know ..Black holes are like...well dense...even denser than a brick or wifeys muffins (and they are ..well dense)


I was watching Horizon last week (also mentioned in another post here )..and some klevur bloke used an analogy that the event horizon was like the edge of waterfall where a swimmer would previously have been able to swim faster than the flow of water but as he/she/it approaches the edge.... the water would be flowing too fast and thus there would be no escape against the flow of water !..not true...

I threw my neighbour in the Victoria falls at 3am this morning (cos I'm a firm believer in empirical study) and with a rope attached to him I proved that I could pull him against the flow of water...I was so happy..I gave a high ten to a passer-by !!...hmmm...I erhm..well..let go of the rope for that !!

So, say I had like a mega strong piece of vine could one end be anchored to spacey ship while the end attached to my neighbour and chucked towards the event horizon and then once passed the event horizon, I could just pull him back yes ?..easy peasy lemon squeezy !!



whajafink ?


hugs & shmishes



mwah mwah mwah !




Neil
Black Hole Inquirer
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« Last Edit: 09/11/2009 14:50:43 by neilep »


 

Offline syhprum

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #1 on: 09/11/2009 15:05:00 »
The escape velocity from the vicinity of the event horizon by definition exceeds c , no amount of tugging on your rope can produce that.
 

Offline neilep

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #2 on: 09/11/2009 15:38:36 »
The escape velocity from the vicinity of the event horizon by definition exceeds c , no amount of tugging on your rope can produce that.

Thank ewe Syhprum...so the chappie was wrong to use the waterfall analogy !

Can I just try and clarify something...ewe have the event horizon yes ?...and everything pass that is is at C or exceeds C...so...how can there be a continuation through the event horizon to the singularity if everything that passes the event horizon is already at infinite speed and density ?
 

Offline Bored chemist

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #3 on: 09/11/2009 19:01:21 »
One of the odd things about the event horizon of a black hole is that you don't know you have crossed it.
If there were something that weirdly stopped you climbing a ladder out of the hole then you would notice it.

I think that , in the same way you could climb a (long enough) ladder away from earth as far as you want without ever needing to reach escape velocity you could do so from a black hole. Of course the ladder would need to be fixed to something outside the hole.

 

Offline Geezer

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #4 on: 10/11/2009 02:08:16 »
Black holes are like...well dense...even denser than a brick or wifeys muffins (and they are ..well dense)

Er, you might want to attach a convex mirror to the display on your PC. I'm pretty sure the Geezercam caught wifey looking over your shoulder while you were typing the above. Looks like she's gone off to the kitchen now to cook up another batch of muffins. I can see her sprinkling something into the mix right now. Can't quite make out what is says on the packet - something like "Ground Gass" perhaps?
 

Offline Mr. Scientist

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #5 on: 10/11/2009 02:12:03 »
One of the odd things about the event horizon of a black hole is that you don't know you have crossed it.
If there were something that weirdly stopped you climbing a ladder out of the hole then you would notice it.

I think that , in the same way you could climb a (long enough) ladder away from earth as far as you want without ever needing to reach escape velocity you could do so from a black hole. Of course the ladder would need to be fixed to something outside the hole.




Oh that's not true at all. In most cases (and no matter how careful you are) - you will feel intense gravitational forces... the tidal effect. Some small black holes can also give off some light, so you would almost certainly know when you had passed that horizon.
« Last Edit: 10/11/2009 02:16:33 by Mr. Scientist »
 

Offline Mr. Scientist

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #6 on: 10/11/2009 02:15:11 »
Dearest Luffly Black Holeologists,

As a sheepy I of course own my very own black hole !..it's pert and neat and has a luffley rim.


As ewe all well know, Black holes are made from liquorice in Pontefract thusly,


Pontefract Black Holes Earlier Today

Hmmm..being delivered next Tuesday...

As ewe also know ..Black holes are like...well dense...even denser than a brick or wifeys muffins (and they are ..well dense)


I was watching Horizon last week (also mentioned in another post here )..and some klevur bloke used an analogy that the event horizon was like the edge of waterfall where a swimmer would previously have been able to swim faster than the flow of water but as he/she/it approaches the edge.... the water would be flowing too fast and thus there would be no escape against the flow of water !..not true...

I threw my neighbour in the Victoria falls at 3am this morning (cos I'm a firm believer in empirical study) and with a rope attached to him I proved that I could pull him against the flow of water...I was so happy..I gave a high ten to a passer-by !!...hmmm...I erhm..well..let go of the rope for that !!

So, say I had like a mega strong piece of vine could one end be anchored to spacey ship while the end attached to my neighbour and chucked towards the event horizon and then once passed the event horizon, I could just pull him back yes ?..easy peasy lemon squeezy !!



whajafink ?


hugs & shmishes



mwah mwah mwah !




Neil
Black Hole Inquirer
xxxxxxxxxxxxxxxxxxx



Yeh, there is a way for you to get out, but not in a way so that your life is spared. There is no way we could tug you on a rope because the gravitational forces are simply too strong. Only tachyons could sucessfully move throughout a black hole.

No, the accepted model is that anything that fall in, immediately tunnels back out of the black hole as to retain energy. This removes the information paradox.

http://www.newscientist.com/article/dn6151-hawking-cracks-black-hole-paradox.html

You'd be nothing but a scramble of particles though.
 

Offline Bored chemist

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #7 on: 10/11/2009 06:57:06 »
One of the odd things about the event horizon of a black hole is that you don't know you have crossed it.
If there were something that weirdly stopped you climbing a ladder out of the hole then you would notice it.

I think that , in the same way you could climb a (long enough) ladder away from earth as far as you want without ever needing to reach escape velocity you could do so from a black hole. Of course the ladder would need to be fixed to something outside the hole.




Oh that's not true at all. In most cases (and no matter how careful you are) - you will feel intense gravitational forces... the tidal effect. Some small black holes can also give off some light, so you would almost certainly know when you had passed that horizon.
Your assertions are only truefor a small black hole.
For a big enough blackk hole it would be possible to take notes as you fell through.
In that instance I don't see what would stop you cimbing back out again.
 

Offline Mr. Scientist

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #8 on: 10/11/2009 09:46:33 »
I've heard ''scientists'' or should i say, trainee scientists argue that a large enough spinning black hole can be entered. I am weery to the arguement, considering that we are made from such loosely-connected particles in such a strong centrifugal force. But that's all nit-picking really. Essentially, you would still feel the gravitational tidal effect, whether or not one passed sucessfully past the event horizon.
 

Offline neilep

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #9 on: 10/11/2009 12:04:32 »
Black holes are like...well dense...even denser than a brick or wifeys muffins (and they are ..well dense)

Er, you might want to attach a convex mirror to the display on your PC. I'm pretty sure the Geezercam caught wifey looking over your shoulder while you were typing the above. Looks like she's gone off to the kitchen now to cook up another batch of muffins. I can see her sprinkling something into the mix right now. Can't quite make out what is says on the packet - something like "Ground Gass" perhaps?

Believe me Geezer..she doesn't need to add anything toxic/dangerous...all she need do is cook !
« Last Edit: 10/11/2009 12:06:16 by neilep »
 

Offline neilep

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #10 on: 10/11/2009 12:06:05 »
Thank you all for our very interesting responses, Bored Chemist and Mr Scientist

I really appreciate the time ewe take to comment.
 

Offline graham.d

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #11 on: 10/11/2009 12:07:54 »
The event horizon is the surface from which you could not escape to infinity (or any great distance). Because we tend to think of black holes as spheres from which no light emerges and think of viewing them from some considerable distance, the event horizon becomes synonomous with the notional object itself: a black hole. In fact, as you approach a black hole the surface which you think of as the event horizon would get smaller because the light may not be able to escape to infinity from this lower surface, but it can get as far as your position (allbeit highly redshifted). If the black hole were large enough you could pass through the event horizon (the surface as viewed from a long way off) so that you could not return from whence you came, but may not have noticed the increase in the gravitational tidal forces (because the BH was so big). The black hole would look like a slightly smaller one still ahead of you. (Don't try this at home, kids).

The spinning black hole can allow, mathematically, the possibility of revealing a naked singularity I believe. My brain runs out of steam here. There are all sorts of speculations about what this would mean.

So I think, in theory, you can go through an event horizon but survive (on an orbiting planet for example) even though you can never go back to where you started. The BH has to be big enough that you don't get stretched to death by tidal forces of course.
 

Offline neilep

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« Reply #12 on: 10/11/2009 15:51:12 »
The event horizon is the surface from which you could not escape to infinity (or any great distance). Because we tend to think of black holes as spheres from which no light emerges and think of viewing them from some considerable distance, the event horizon becomes synonomous with the notional object itself: a black hole. In fact, as you approach a black hole the surface which you think of as the event horizon would get smaller because the light may not be able to escape to infinity from this lower surface, but it can get as far as your position (allbeit highly redshifted). If the black hole were large enough you could pass through the event horizon (the surface as viewed from a long way off) so that you could not return from whence you came, but may not have noticed the increase in the gravitational tidal forces (because the BH was so big). The black hole would look like a slightly smaller one still ahead of you. (Don't try this at home, kids).

The spinning black hole can allow, mathematically, the possibility of revealing a naked singularity I believe. My brain runs out of steam here. There are all sorts of speculations about what this would mean.

So I think, in theory, you can go through an event horizon but survive (on an orbiting planet for example) even though you can never go back to where you started. The BH has to be big enough that you don't get stretched to death by tidal forces of course.

Thank Ewe very much graham.d Phew !!..Black Holes are mysterious beasties. I think I need to push my neighbour into one so that he can report back.  :-)
 

Offline litespeed

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #13 on: 10/11/2009 19:54:59 »
I be interested in yee wifie's relativistic biscuits. Me thinks they may need delivery to the LHC in short order.
 

Offline litespeed

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #14 on: 10/11/2009 20:14:05 »
neil

I just do not see anything out of the ordinary in a black hole. IMHO they are subject to the same rules of physics as everything else. For some reason, people get all rhapsodic  about what they can't see. 

For instance, I have yet to find (and I have been looking for at least a year) anyone who can convince me a neutron star can become a Black Hole through simple mass acretion. However, a neutron star that has enough supernova mass left over and available to collapse back at relativistic velocities simply achieves relativistic effects.

I see no contradiction that a neutron star can exist as such in a black hole, while all the other relativistic mass collapsing onto it simply never gets there.  And as far as I can tell, the mass of a BH simply increases over time. No singularities, not hocus pocus of any kind. With ONE exception. At relativistic speeds we should observe MASS dialation as well. Has ANYONE explored this issue?



 

Offline Geezer

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #15 on: 10/11/2009 20:22:35 »
I be interested in yee wifie's relativistic biscuits. Me thinks they may need delivery to the LHC in short order.

Wifey's muffins would, in Glasgow patter (patois), be described as "stoaters". A "stoater" is someting that "stoats" because it has certain elastic qualities that make it virtually indestructible. For example, one may "stoat" a rubber ball off a brick wall or the pavement. Therefore, wifey's muffins might make useful substitutes for cricket balls for instance because of their remarkable stoatability.
 

Offline neilep

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #16 on: 18/11/2009 17:26:27 »
neil

I just do not see anything out of the ordinary in a black hole. IMHO they are subject to the same rules of physics as everything else. For some reason, people get all rhapsodic  about what they can't see. 

For instance, I have yet to find (and I have been looking for at least a year) anyone who can convince me a neutron star can become a Black Hole through simple mass acretion. However, a neutron star that has enough supernova mass left over and available to collapse back at relativistic velocities simply achieves relativistic effects.

I see no contradiction that a neutron star can exist as such in a black hole, while all the other relativistic mass collapsing onto it simply never gets there.  And as far as I can tell, the mass of a BH simply increases over time. No singularities, not hocus pocus of any kind. With ONE exception. At relativistic speeds we should observe MASS dialation as well. Has ANYONE explored this issue?





FASCINATING !!...thank ewe very much litespeed  Perhaps ewe are right and there is a far simpler explanation, it would save having to over-complicate matters !
 

Offline itisus

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #17 on: 01/12/2009 05:39:55 »
Regarding collapse of a neutron star to a black hole:

Here is an explanation that even I can more or less understand, although I won't try to explain it:
http://people.hofstra.edu/stefan_Waner/diff_geom/Sec16.html

Adding mass moves the event horizon out to the surface of the star.


« Last Edit: 01/12/2009 05:47:45 by itisus »
 

Offline yor_on

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #18 on: 31/01/2010 23:47:17 »
Dearest Luffly Black Holeologists,


I was watching Horizon last week (also mentioned in another post here )..and some klevur bloke used an analogy that the event horizon was like the edge of waterfall where a swimmer would previously have been able to swim faster than the flow of water but as he/she/it approaches the edge.... the water would be flowing too fast and thus there would be no escape against the flow of water !..not true...

I threw my neighbour in the Victoria falls at 3am this morning (cos I'm a firm believer in empirical study) and with a rope attached to him I proved that I could pull him against the flow of water...I was so happy..I gave a high ten to a passer-by !!...hmmm...I erhm..well..let go of the rope for that !!

So, say I had like a mega strong piece of vine could one end be anchored to spacey ship while the end attached to my neighbour and chucked towards the event horizon and then once passed the event horizon, I could just pull him back yes ?..easy peasy lemon squeezy !!


Neil
Black Hole Inquirer
xxxxxxxxxxxxxxxxxxx


It's complicated :)

First of all, the Event horizon is the idea of a place where from a photon won't be able to bounce back, once passing that 'place' all light will have only one way to go, inwards. Of course the same will hold true for all other thingies we know of too, inside our arrow of time that is, like 'matter'.

What it won't hold true for is Hawking radiation.


" Hawking predicted that energy fluctuations from the vacuum causes the generation of particle-antiparticle pairs near the event horizon of the black hole. One of the particles falls into the black hole while the other escapes, before they have an opportunity to annihilate each other. The net result is that, to someone viewing the black hole, it would appear that a particle had been emitted.

Since the particle that is emitted has positive energy, the particle that gets absorbed by the black hole has a negative energy relative to the outside universe. This results in the black hole losing energy, and thus mass (because E = mc2).

Smaller primordial black holes can actually emit more energy than they absorb, which results in them losing net mass. Larger black holes, such as those that are one solar mass, absorb more cosmic radiation than they emit through Hawking radiation.  "

The idea here revolves around an entanglement as I understands it, happening faster than Planck time it will allow the entanglement to work at all places, including inside that black hole, or most probably inside, as that place should be a virtual whirlpool of 'virtual particles' popping in and out due to gravity/energy, but the virtual particles 'net energy' inside will then still be a zero creating no loss of mass. When/if it happens at the EV though, there exist this weird possibility of the pair splitting up creating the effect above.

What one should notice though is that as long as it still is a black hole, you can't really say that there is any form of 'communication' involved. There is no way we can prove that the entanglement isn't destroyed instantly by their split, also one have to remember that this entanglement then would come from something outside our 'arrow of time' as it is under Planck time and therefore won't hold any 'information' about SpaceTime, that is, if we define SpaceTime as a system following the arrow we observe macroscopically.

If we don't define SpaceTime as such I don't see how we can have a closed SpaceTime and if we can't have that I fail to see how we can prove the idea of 'energy can neither be created (produced) nor destroyed by itself. It can only be transformed.' At a QM level time becomes indeterminate and expresses itself through its 'events' or 'process chains' as in Feynman diagrams.  And as virtual particles then both will communicate with singularities as well as suddenly 'transform' into energy inside our arrow of time then a Black Hole can't be defined as a singularity any more but have be a integrated part of our SpaceTime too? Also we then will have to include those processes under Plank time as being SpaceTime? Which then fail to make sense to me :)if we still believe SpaceTime to be a infinite but closed process/system.

Never the less, if there is a event horizon it seems to act very strangely.

---Quote---

A misconception concerning event horizons, especially black hole event horizons, is that they represent an immutable surface that destroys objects that approach them. In practice, all event horizons appear to be some distance away from any observer, and objects sent towards an event horizon never appear to cross it from the sending observer's point of view (as the horizon-crossing event's light cone never intersects the observer's world line). Attempting to make an object approaching the horizon remain stationary with respect to an observer requires applying a force whose magnitude becomes unbounded (becoming infinite) the closer it gets.

For the case of an horizon perceived by a uniformly accelerating observer in empty space, the horizon seems to remain a fixed distance from the observer no matter how its surroundings move. Varying the observer's acceleration may cause the horizon to appear to move over time, or may prevent an event horizon from existing, depending on the acceleration function chosen. The observer never touches the horizon, and never passes a location where it appeared to be.

For the case of an horizon perceived by an occupant of a De Sitter Universe, the horizon always appears to be a fixed distance away for a non-accelerating observer. It is never contacted, even by an accelerating observer.

For the case of the horizon around a black hole, observers stationary with respect to a distant object will all agree on where the horizon is. While this seems to allow an observer lowered towards the hole on a rope to contact the horizon, in practice this cannot be done. If the observer is lowered very slowly, then, in the observer's frame of reference, the horizon appears to be very far away, and ever more rope needs to be paid out to reach the horizon. If the observer is quickly lowered by another observer, then indeed the first observer, and some of the rope can touch and even cross the (second observer's) event horizon. If the rope is pulled taut to fish the first observer back out, then the forces along the rope increase without bound as they approach the event horizon, and at some point the rope must break. Furthermore, the break must occur not at the event horizon, but at a point where the second observer can observe it.

Attempting to stick a rigid rod through the hole's horizon cannot be done: if the rod is lowered extremely slowly, then it is always too short to touch the event horizon, as the coordinate frames near the tip of the rod are extremely compressed. From the point of view of an observer at the end of the rod, the event horizon remains hopelessly out of reach. If the rod is lowered quickly, then the same problems as with the rope are encountered: the rod must break and the broken-off pieces inevitably fall in.

These peculiarities only occur because of the supposition that the observers be stationary with respect to some other distant observer. Observers who fall into the hole are moving with respect to the distant observer, and so perceive the horizon as being in a different location, seeming to recede in front of them so that they never contact it. Increasing tidal forces (and eventual impact with the hole's gravitational singularity) are the only locally noticeable effects. While this seems to allow an in-falling observer to relay information from objects outside their perceived horizon but inside the distant observer's perceived horizon, in practice the horizon recedes by an amount small enough that by the time the in-falling observer receives any signal from farther into the hole, they've already crossed what the distant observer perceived to be the horizon, and this reception event (and any retransmission) can't be seen by the distant observer.

---End of quote----

From Event horizon 

And conservation_of_energy

So according to those scenarios you won't be able to be saved Neil, if you don't decide to eat it up of course :), in which case you could save some for us too perhaps
==

Ah, I see, your neighbor was it?
Irritating chap, what?

 

Offline itisus

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
« Reply #19 on: 01/02/2010 07:14:19 »
Actually nobody has been there and lived to tell about it, nobody has seen anything cross the horizon, and maybe nothing does.  The solution is based on the idea that a vacuum solution that could be valid only if continued to infinity in flat space makes sense in the first place.  Don't worry about it.  Rotating black holes are real and Schwarzschild ones may occur, but nobody actually knows what happens at the EH.
 

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Can I Be Rescued From The Event Horizion Of A Black Hole ?
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