Has the Event Horizon a Grip ?

[Spyman]

Would the Event Horizon around a Black Hole clamp a stick that penetrates it like a giant Bench Vice or cut it off softly as if that part would suddenly vanish ?

 

Lets say we have a non rotating Supermassive Black Hole in a big void, (so it is starving), in theory it would be possible to visit the Event Horizon with a powerful spaceship for a short timespan while you pass by, as long as you don't cross it.

 

Now, if the spaceship has a metal bar sticking out and by purpose we let the bar cross the Event Horizon during the fly-by, would the internal forces keeping the bar togheter still act through the Event Horizon, which would deform and eventually break the bar from the inertia of the BH and the fast moving spaceship? Or would the part on the other side be separated without any detectable force on the bar/spaceship?

 

In popular science it is often mentioned that you could pass the Event Horizon of a Supermassive Black Hole without noticing. But I think I would notice if I suddenly couldn't feel my legs anymore and my blood would stop returning from them. Even if you where to pass the Event Horizon very quickly there shouldn't be any difference inside, if "all paths in the forward light cones of particles within the horizon, are warped so as to fall further into the hole".

[swansont]

It might depend on where the tidal forces exceed the sheer strength of the material.

[Spyman]

I am not asking about Spaghettification close to normal sized Black Holes.

 

The tidal forces at the Event Horizon of a non rotating Supermassive Black Hole are significantly weaker, since the central singularity is so far away from the horizon.

 

It's a relativity question, with Newton gravity you could still pull out something from inside with a rope, but as I understand GR it's impossible.

 

If I where to put a camera on the end of the metal bar would it be able to send pictures, by cable, out to the spaceship, from inside the EH ?

[lakmilis]

Well Spyman, those questions no one has the answers too, we all interpret and make educated guesses but the fact is , GR does break down, Schwarzchild radius or event horizon is not even necessarily valid....SR converges on half the value of the Schwarz. radius (event horizon)... SR predicts somewhat that holes would have to be rotatory...(yes yes I know, this is the area of GR and not SR, but just pointing out that in SR , the radius would be 1m). schw. metric gives ya 0 and 2m as solutions for the singularity radius and the horizon radius, which again defines 'quantum levels' between the singularity radius and the event horizon... What really would happen as we got close or put a leg through or a camera??? Your guess is as good as anyone elses, as long as it correlates with that which can be.

 

Well, I still am wondering are black holes really dense matter'( dunno, a quark soup maybe?? tough one) or actual holes( if so, it really really proves we have a loooong way to go to understand the 'fabric' of space itself)... we don't even know that... The idea of wormholes thanks to science fiction as well makes us easily believe holes have this property... but this is far from sure.

 

I mean, how does a hole rotate??? if I claimed to you that a hole in the ground was rotating, would you accept it? I doubt it, but if you saw the edges of the hole seem to move then something else would be moving....either the air in the hole was rotating so you could see dirt fall off, or else it must be the edges itself rotating...well in space I assume we agree that space edges around a hole are not rotating... so you see the conundrum?

 

Looking at the dynamics of 'how' black holes are created is still a more important aspect of black hole studies which first must be better understood. I till this day do not know if I can accept that 'any' celestial object can exert enough gravitational force on itself to implode to such an entity as a black hole.. for me this would seem to be the same as saying one needs to accelerate to the speed of light..it would take infinite energy...the idea of gravitational collapse only just doesnt seem viable to me. Extreme rotational energy must surely also be present... However, neutron stars seem to be rotating far slower than I expected so I am still at a loss how such things can be created. ( I was hehe , pretty purely intuitively guessing neutron stars would be up at 0.6c in rotational velocities but they are nowhere near that).

[lakmilis]

Oh and to answer that then with my ways of thinking.... well, should one disregard one reality to then speculate about what happens? taking away the gravitational pull would imply lets say some fancy hanky panky devices which made ya immaterial to the pull ye? would this not then affect you as you then try to finally find out what happens when you pull your swimming trunks up and dip your leg into the horizon?? First figure how to get to the hole realistically, if you can do that, then you probably can come up with a good guess what indeed happens at the horizon :x

 

and no, I dont think black holes EVER will be the answer to 'space travel' and yes I do think we one day will... I believe though it will be perhaps more of the form of QM matter encoding and decoding. Making links where we're zapped , dissolved into superpositioned photon? pairs , where another end perhaps has a way of decoding the information sent (look up the aspect experiment, think thats the name?) into matter identical in its grid, n with a bit of luck, our minds are still connected to the brain and lalila

(well it would be better to say with a bit of luck our bodies would reconnect with the mind )

[Spyman]

Hi lakmilis, I am not quite sure how to interpret your post...

 

Well Spyman, those questions no one has the answers too, we all interpret and make educated guesses but the fact is , GR does break down, Schwarzchild radius or event horizon is not even necessarily valid....

Are you claiming that mainstream science and people like Roger Penrose, Abhay Ashtekar, Stephen Hawking, Martin Bojowald and so on... are only making "educated guesses" ???

 

Hmm, I was under the impression that GR works fine, even inside the Event Horizon, except for close to the singularity, (Planck scale) ?

(Hopefully one of the Experts will make a clear statment on that.)

 

You seem to imply that if BH exists, it could still be possible to escape from inside the radius of EH ?

(Heh, how did I ever get so conviced that GR forbids that...)

 

Oh and Yes sure, BHs are not definately proven yet, but all evidence so far indicates a high probability, and they are "inevitable in physically reasonable situations".

(In this thread the BH is assumed, with a spaceship already there.)

[Severian]

The event horizon is just the point where you cannot return in principle, even if you really really try very hard.

 

All gravitational objects have what is called an escape velocity. This is a speed that you have to acheive to be able to leave the object behind (get out of its gravitational potential). For example, for the Earth it is around 40,000 km/h (so pretty fast!).

 

A black hole is not really any different, and in my opinion is really far too glamourised in science. A black hole is just when the body' escape velocity is greater than the speed of light, so nothing can obtain the escape velocity, not even light (which is why it is 'black').

 

But everything else is the same. If you could hypothetically build a spaceship (and crew) which was able to withstand the tidal forces, you could pass over the event horizon like normal and wouldn't really notice. You would only notice when you tried to get out again.

 

The downward force on your legs is perfectly continuous as you pass the event horizon. It doesn't suddenly become huge and chop them off. However, it is already huge, so you have probably not felt your legs for quite some time, because the energy required to pass the blood or nerve signal up your legs was probably far too much already 10 miles up!

 

You would only stop feeling your legs as you pass the horizon if you are some sort of light-based creature whose legs communicate with the rest of you by sending light signals.

[Farsight]

In answer to the original post, the event horizon does have a grip. But it's subtle. It sneaks up on you.

 

Let's imagine a small black hole and a spaceship with a very long metal bar sticking out of the side of it. The spaceship does a flyby, and the metal bar makes contact with the event horizon. Spang! The bar breaks off.

 

The reason it does this is that at the event horizon, time dilation goes infinite. The end of the metal bar cannot move anymore. It has no time in which to move. It's like hitting a brick wall. If you could walk all around it and peer closely, you'd see that the end of the metal bar had melded itself into this "brick wall" and was a part of it. And nothing but nothing is moving.

 

This is why black holes were originally called "frozen stars". All the stars that have collapsed have in essence not finished collapsing, and never ever will.

 

You'll hear about the "proper time" of an infalling object, but that proper time is an abstraction and not a reality.

 

Interesting stuff.

[pcollins]

As I understand Spyman's question, it's two parts.

 

1. What would an observer in a frame comoving with some spherical mass orbiting a supermassive black hole see if that masses' radius intersected with the horizon such that the center of gravity remains outside.

 

2. What would a distant observer see?

 

I'd like to actually see the math worked out on this one.

[Spyman]

All gravitational objects have what is called an escape velocity. This is a speed that you have to acheive to be able to leave the object behind (get out of its gravitational potential). For example, for the Earth it is around 40,000 km/h (so pretty fast!).

If I had a hypothetically stair continuing from Earths surface up into space, could I not use it to leave Earth behind at any speed desired ?

At least I can increas my distanse a few meters with my stairs at home and I can't se any reason to prevent me if the stairs would continue.

 

A black hole is not really any different, and in my opinion is really far too glamourised in science. A black hole is just when the body' escape velocity is greater than the speed of light, so nothing can obtain the escape velocity, not even light (which is why it is 'black').

So if I was able to withstand the huge gravitational forces and had a likewise stair could I still use it climb out from inside the EH ?

(According to your first sentence, Nope.)

The event horizon is just the point where you cannot return in principle, even if you really really try very hard.

With GR there is an important difference !

 

But everything else is the same. If you could hypothetically build a spaceship (and crew) which was able to withstand the tidal forces, you could pass over the event horizon like normal and wouldn't really notice. You would only notice when you tried to get out again.

Is it impossible to have a Supermassive Black Hole so big that the tidal forces out at the EH is lower than as on Earth surface ?

(Tidal forces is not the issue here.)

 

The downward force on your legs is perfectly continuous as you pass the event horizon. It doesn't suddenly become huge and chop them off. However, it is already huge, so you have probably not felt your legs for quite some time, because the energy required to pass the blood or nerve signal up your legs was probably far too much already 10 miles up!

The downward gravitational force is "perfectly continuous" yes, but is there a force acting upward through the EH, that would keep my legs attached to my body ?

(Like if I would change my mind and try to pull my legs out, would I be stuck in the EH ?)

 

You would only stop feeling your legs as you pass the horizon if you are some sort of light-based creature whose legs communicate with the rest of you by sending light signals.

If I interpret this correct, then you are saying that the blood in my veins and the signals from my nerves would be able to move up through the EH from my legs to my body still outside but I wouldn't be able to se them any more because photons can't pass.

(I really doubt my blood flows faster than c. )

[Spyman]

Let's imagine a small black hole and a spaceship with a very long metal bar sticking out of the side of it. The spaceship does a flyby, and the metal bar makes contact with the event horizon. Spang! The bar breaks off.

So you think that the end of the metal bar that get caught inside the EH would still be able to communicate it's part of the internal, (nuclear), forces inside the metal bar to the outside part and physically break it ?

[Spyman]

As I understand Spyman's question, it's two parts.

 

1. What would an observer in a frame comoving with some spherical mass orbiting a supermassive black hole see if that masses' radius intersected with the horizon such that the center of gravity remains outside.

 

2. What would a distant observer see?

 

I'd like to actually see the math worked out on this one.

Nope, I am not interested in how it would look from different frames, I want to know what would happen to the part above the EH when the other part of the bar get's caught in/below the EH.

 

Would it snap off or be cut off ???

 

When the spaceship returns to the distant observer they must be able to agree on how the bar is deformed.

[Severian]

If I had a hypothetically stair continuing from Earths surface up into space, could I not use it to leave Earth behind at any speed desired ?

At least I can increas my distanse a few meters with my stairs at home and I can't se any reason to prevent me if the stairs would continue.

 

Yes, you could do this in principle on the Earth (eg. a space elevator) but you couldn't on a Black Hole because the energy to overcome the gravitation would be infinite.

 

With GR there is an important difference !

 

Yes, you are right. My description was a little simplistic, although it suffices for the question that was asked.

 

Is it impossible to have a Supermassive Black Hole so big that the tidal forces out at the EH is lower than as on Earth surface ?

(Tidal forces is not the issue here.)

 

I am not sure what you are asking.

 

The downward gravitational force is "perfectly continuous" yes, but is there a force acting upward through the EH, that would keep my legs attached to my body ?

(Like if I would change my mind and try to pull my legs out, would I be stuck in the EH ?)

 

I think what I said before was slightly wrong. Your legs would not be able to communicate with your body in any way, so there could be no passing of momentum, so no force. In other words, the gauge bosons which mediate the other forces are as trapped in the BH as everything else is. So your legs would be 'chopped of'' after all. The point I was making is that you would have lost your legs long before the EH because the effective force carriers are travelling slower than c, so their 'EH' is further out.

 

If I interpret this correct, then you are saying that the blood in my veins and the signals from my nerves would be able to move up through the EH from my legs to my body still outside but I wouldn't be able to se them any more because photons can't pass.

(I really doubt my blood flows faster than c. )

 

No. the nerves signals don't move anywhere near c.

[Farsight]

So you think that the end of the metal bar that get caught inside the EH would still be able to communicate its part of the internal, (nuclear), forces inside the metal bar to the outside part and physically break it ?

 

There's no getting caught "inside" the horizon. Time dilation goes to infinity as you approach it. Everything stops. Utterly, absolutely. People talk about "proper time" but there's no time left. Hence as far as our metal bar is concerned the event horizon is like glue of infinite strength. The spaceship does a flyby, the end of the bar skims closer to the horizon then when it reaches it, it stops. The spaceship keeps on going. The bar breaks.

 

There's other things happening too, such as the tidal forces pulling down on the bar, but if you imagine a small black hole and a very long bar with the spaceship zipping by real fast, the spaceship has gone and the bar is broken long before the tidal force has done its stuff.

 

If you want to consider the tidal force, you can think of the bar as something like taffy: the end of it will be pulled downwards by the enormous gravity. Once it arrives at the location where time dilation is infinite it isn't coming back. No way, no how. If the bar was really strong the spaceship would change course and start going round and round the black hole like it was on a tetherpole, then wham, gone. But if the bar is fairly weak it'll snap and the spaceship escapes. I don't know if you know, but steel is rather like toffee. If you cool it slowly it's soft, something like fudge. If you cool it quickly it's brittle, more like butterscotch.

[lakmilis]

 

Are you claiming that mainstream science and people like Roger Penrose, Abhay Ashtekar, Stephen Hawking, Martin Bojowald and so on... are only making "educated guesses" ???

 

Hmm, I was under the impression that GR works fine, even inside the Event Horizon, except for close to the singularity, (Planck scale) ?

(Hopefully one of the Experts will make a clear statment on that.)

 

First of all, nice and interesting reply, saw it in the morning but didn't have time to reply before a bunch of posts would come since I was preparing some work.

 

ok, replies in reverse order. No, GR does predict its own demise behind the 2m radius (well , with the Schwarzc. metric). Yes, I do believe that GR does *not* work or work as any predictive meausere beyond the event horizon.

If this is wrong, I am happy to hear from someone argue for the opposite.

 

What is 'between' the singularity and the EH, yup is absolutely educated guesses. The 0 and 2m answers from the scharschild metric took time to interpret by some of the very people you mention.

 

Yes, it follows that the interpretations of what goes on beyond the eH are indeed educated guesses. However, Penrose and the others will obviously be having some very good ones, don't you agree?

 

I believe that it was precisely Penrose who stated the 'cosmic censorship' principle, that no singularity can be únshielded' in nature. Aka , this is results of their interpretations of the 'problem of the 2 answers'. (Won't go into more right now, probably with a little luck other views on this will be given ).

You seem to imply that if BH exists, it could still be possible to escape from inside the radius of EH ?

(Heh, how did I ever get so conviced that GR forbids that...)

 

No no, I did not imply that, where? No , I am part of the mainstream community which today are quite happy with the current indicative data that black holes exist. And no, what I said was exactly the opposite, from GR and the logic behind the event horizon, all these fancy ideas of taking away realistic problems (like tidal ways, escape velocity, etc etc) to see if we could escape is for me silly. Since GR *does* work from the very limit of the EH and onwards and escape energies and mass (since even light) just won't be able to escape. thats why i mentioned black holes I believe will always be black holes of destruction, not some magic portal we are trying to imagine wihtout gravitational effects from GR.... but I am making an educated guess , just like others. I do believe however in alternate ways of lets say tachyon transfer. (tachyons here not meaning particles but a field).

 

Artificial curvature of vacuum is something else though in my opinion. There the gravitational pull would not necessarily exist if it was not density of mass which created it, but nevermind, this is again speculation. However more befitting to ponder about with regards to your initial question

 

A last thing on that part, Hawking radiation if that is why you think about it, is a different ball game altogether as well. This is hypothetical models put forward by Hawkings on virtual particles. The logic behind them is not a derivative of GR, but rather QM in its broad sense, thermodynamics, etc.

 

Again, let me just remind you that this has also no indicative proof yet as such, it is a proposal which is conistent with other effects seen in experimental physics and it is perfectly eligible to discussion. It is not fact, it is proposed to be perhaps be so.

 

Oh and Yes sure, BHs are not definately proven yet, but all evidence so far indicates a high probability, and they are "inevitable in physically reasonable situations".

(In this thread the BH is assumed, with a spaceship already there.)

 

Yes sure, but like I said, I never indicated black holes don't exist. I was talking rather about the dynamics behind their creation. You see, I just mentioned that I believe extreme angular momentum must be also involved... And I put more trust in the Kerr metric.. (simply because if one plays around with SR [in est, special relativity], it will indicate that from a non-rotating black hole, the EH should be half of what the 2m answer from Schwarz is). The problem is that the Kerr holes are non-rotatory I believe, so I am stuck in between the Kerr metric but swearing to rotation. However like I said, a good set of data for gravitational collapse being sufficient as the only force needed for sub-S.R. (in est, Schwarzchild Radius) collapse, then I will be happy with Kerr's non-rotatory metric.

 

lakmilis

 

OMG, sorry I worked on this years ago, Kerr holes DO rotate... sorry I rememebr though I had a problem with kerr holes as well. Give me a little recap on manifolds and I will maybe say something less silly...I will leave the post unedited, both the syntactical *and* the semantic scientific errors...but add the apology of stating the Kerr holes don't rotate. In any case, I find the Kerr metric more logically consistent than the Schw. metric

 

lak

[lakmilis]

Oh, and about the elevator and escape velocity....hmm, I didn't think you could just walk little by little...no matter how much you try you wouldn't be able to overcome the potential energy required to escape if you would be walking slowly, surely.... thats the whole point of escape velocity...

 

A derivative of this is Tsialkowsky? equations on why a rocket can not leave earth's gravitional field with only one rocket, due to mass relations and obtainable velocity

 

lak

[lakmilis]

ok and finally, trying to still answer what I think might happen *with* all other effects, entering a BH? No I just do not think a ship , bar or camera as we know it can do it, we will become that intensely stretched, and so interchanged matter to plasma going towards light.......... entering the EH at such a massssiiiiivvvve speed that minute a part of the plasma soup hits the EH, it ziiipppsss straight into the singularity in a quantum leap hehe, and like pulling water apart, that which is still immediately outside the EH is just disconnected. To imagine mass in ground state (lol forgot what its called, non plasma, non gaseous, non liquid ) is just defying the whole understanding of a black hole. Supermassive black holes with sufficiently low gravitational gradient for us to keep our shape just outside its EH...no way... if that can be shown through any link to data, please url me

 

But for the record, by actually saying that 2m n 0 radii can get enough apart that the gradient is lowered, means something very interesting as we can't forget that the distance between 0 and 2m radii is per definition *not* part of space, so we can't plot our entity within with the minkowski coordinates!!

[lakmilis]

And ok, now that I got pissed out of me mind last night, I wake up with less overall total memory, but I do realize you were kind of right, thanks for reminding me. Yes, I do remember now that back in the days I did indeed query and suggest Schwarzchild (non-rotating) black holes do not exist (a suggestion, not a hard claim ) Kerr holes though yaps, more elegant, more thought through and also logically more consistent with this phenomena

[lakmilis]

hmm, had a weird dream today and for the love of God, I didn't memorise it when I woke up... and lol it was Pauli's exclusion principle similar in degenerate matter superimposed upon a macroscopic grid of space... (I remember in the dream or think I do), that a naked ring singularity would be stable if it was surrounded by equidistant entities. Well actually they were not equidistant, it was one black hole, one something else and another thing keeping 2 ring singularities (I 'think') within the same space. One had to move and when it did (as there was allowance for it on this 'grid'), then the other one remained stable interlocked between these entities. Lol, anyway I will never be able to recap what that dream told me, but still struck me, if twin or even triplet black holes...had exact same gravitational pull , then if you approached at a certain axis w.r.t to this system, you could find a centre point where all pulls cancelled each other out. For arguments sake , say a multiple system or mini cluster of black holes were distributed around an axis in such a way that you didnt accelerate too fast , avoiding the spaghettification and the like until reaching a centre point, between at least 2 holes, where these were held extremely close to each other but cancelled each others pull out due to surrounding cluster holes, then yes, I guess one could indeed come very close to an event horizon feeling a theoretically low pull.

 

How about that, does that sound interesting to initial poster to bring the topic back a bit to your question?

 

Hmmm, I do think though that regardless of the ergosphere/photonsphere, that the even horizon as well must have a ring of circuling photons; in that exact moment you will have a bunch of interesting energy hypothesis due to if one could indeed put that lovely leg through it, or even ones head, then one could indeed interact with the photons as such. Beyond the horizon or even trying to withdraw from it is just plain speculation before we know more if QM or GR or whatever else should be the one corrected behind the EH. (see Hawkings and'Preskill's bet for example).

[Spyman]

Is it impossible to have a Supermassive Black Hole so big that the tidal forces out at the EH is lower than as on Earth surface ?

(Tidal forces is not the issue here.)

I am not sure what you are asking.

The point I was making is that you would have lost your legs long before the EH because the effective force carriers are travelling slower than c' date=' so their 'EH' is further out.[/quote']

Well, I might be wrong here but outside of the EH, (for light), the stairs mentioned before should still work. So with a very large, billions of solar masses, BH, the tidal forces at the distance of the EH would be weak and thus the pilot in a powerfull spaceship passing by in a reasonable trajectory at very high speed, could be almost in freefall.

 

Supermassive black holes have some interesting properties which distinguish them from relatively low-mass cousins:

 

* The average density of a supermassive black hole can be very low, and may actually be lower than the density of air. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, and mass merely increases linearly, the volume increases at a greater rate than mass. Thus, density decreases for increasingly larger radii of black holes.

* The tidal forces in the vicinity of the event horizon are significantly weaker. Since the central singularity is so far away from the horizon, a hypothetical astronaut travelling towards the black hole center would not experience significant tidal force until very deep into the black hole.

http://en.wikipedia.org/wiki/Supermassive_black_hole

 

My question of your point was: Could not, (in theory), the BH be large enough to make it possible for a human to be able to visit the EH, (above but close), during a short fly-by, and then return still alive ?

 

Your legs would not be able to communicate with your body in any way, so there could be no passing of momentum, so no force. In other words, the gauge bosons which mediate the other forces are as trapped in the BH as everything else is. So your legs would be 'chopped of'' after all.

Let's use the metal bar instead, I would like to keep my legs.

 

So the bar gets cut, but it would require work to cut a metal bar in half.

 

How would the "chopping" deal with the conservation laws ?

 

Also from my understanding of GR the same rule would apply to every radius smaller than the EH radius. So if nothing can move up to a higher radius, would everything passing the EH continue to be sliced to the thinnest slices possible as they traverse down to lower and lower radius ?

[Spyman]

So you think that the end of the metal bar that get caught inside the EH would still be able to communicate it's part of the internal, (nuclear), forces inside the metal bar to the outside part and physically break it ?[/quote']There's no getting caught "inside" the horizon. Time dilation goes to infinity as you approach it. Everything stops. Utterly, absolutely. People talk about "proper time" but there's no time left. Hence as far as our metal bar is concerned the event horizon is like glue of infinite strength. The spaceship does a flyby, the end of the bar skims closer to the horizon then when it reaches it, it stops. The spaceship keeps on going. The bar breaks.

I think you misunderstod my question, I did not mean "caught inside of the EH", I meant "caught inside in the EH".

 

When the atoms in the end of the metal bar gets "frozen" or "glued" will they still be able to mediate the nuclear forces necessarily to ceep the bar together, in one piece, to the rest of the bar still outside.

 

If they will, then the bar would break, if not the bar would be cut off.

 

Wouldn't the nuclear forces be "frozen" in time too, if "everything stops" ?

[Spyman]

No, GR does predict its own demise behind the 2m radius (well , with the Schwarzc. metric). Yes, I do believe that GR does *not* work or work as any predictive meausere beyond the event horizon.

OK lakmilis, nobody knows what the inside of a BH would consist of, how it would look like or if GR would accurately model it, but my point was that GR does not break down.

 

No no, I did not imply that, where? No , I am part of the mainstream community which today are quite happy with the current indicative data that black holes exist....Since GR *does* work from the very limit of the EH and onwards and escape energies and mass (since even light) just won't be able to escape.

So you agree that the end of the bar touching the EH won't be able to escape and that the spaceship above could still return ?

 

Oh, and about the elevator and escape velocity....hmm, I didn't think you could just walk little by little...no matter how much you try you wouldn't be able to overcome the potential energy required to escape if you would be walking slowly, surely.... thats the whole point of escape velocity...

Well it works on Earth, make the test yourself - just try any stairs.

(Escape velocity is for a bullet without further thrust.)

 

ok and finally, trying to still answer what I think might happen *with* all other effects, entering a BH? No I just do not think a ship , bar or camera as we know it can do it, we will become that intensely stretched, and so interchanged matter to plasma going towards light.......... entering the EH at such a massssiiiiivvvve speed that minute a part of the plasma soup hits the EH, it ziiipppsss straight into the singularity in a quantum leap hehe, and like pulling water apart, that which is still immediately outside the EH is just disconnected.

I will interpret this reply as the bar will be cut off at the EH...

 

Supermassive black holes with sufficiently low gravitational gradient for us to keep our shape just outside its EH...no way... if that can be shown through any link to data, please url me

What happens to you if you fall into a black hole?

 

Suppose that, possessing a proper spacecraft and a self-destructive urge, I decide to go black-hole jumping and head for an uncharged, nonrotating ("Schwarzschild") black hole. In this and other kinds of hole, I won't, before I fall in, be able to see anything within the event horizon. But there's nothing locally special about the event horizon; when I get there it won't seem like a particularly unusual place, except that I will see strange optical distortions of the sky around me from all the bending of light that goes on. But as soon as I fall through, I'm doomed. No bungee will help me, since bungees can't keep Sunday from turning into Monday. I have to hit the singularity eventually, and before I get there there will be enormous tidal forces-- forces due to the curvature of spacetime-- which will squash me and my spaceship in some directions and stretch them in another until I look like a piece of spaghetti. At the singularity all of present physics is mute as to what will happen, but I won't care. I'll be dead.

 

For ordinary black holes of a few solar masses, there are actually large tidal forces well outside the event horizon, so I probably wouldn't even make it into the hole alive and unstretched. For a black hole of 8 solar masses, for instance, the value of r at which tides become fatal is about 400 km, and the Schwarzschild radius is just 24 km. But tidal stresses are proportional to M/r3. Therefore the fatal r goes as the cube root of the mass, whereas the Schwarzschild radius of the black hole is proportional to the mass. So for black holes larger than about 1000 solar masses I could probably fall in alive, and for still larger ones I might not even notice the tidal forces until I'm through the horizon and doomed.

 

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html

 

For arguments sake , say a multiple system or mini cluster of black holes were distributed around an axis in such a way that you didnt accelerate too fast , avoiding the spaghettification and the like until reaching a centre point, between at least 2 holes, where these were held extremely close to each other but cancelled each others pull out due to surrounding cluster holes, then yes, I guess one could indeed come very close to an event horizon feeling a theoretically low pull.

 

How about that, does that sound interesting to initial poster to bring the topic back a bit to your question?

Let's not complicate things further...

[lakmilis]

haha to the last comment. sure, just pointing out to you that Schw. holes probably don't exist in nature

 

so you asking if I agree, back to what I said about educated guesses then

 

Yes, I know the theory about the supermassive black holes, but again like I said, thats assuming a supermassive black hole is a Schwar. hole, something I will go along with as long as we say its a Kerr hole, in that case, a supermassive hole will provide framedragging of such proportions that we are back to the complex situation of having great problems being near to an EH

 

And to your first comment, GR doesnt break down beyond EH??

well, I guess I couldn't disagree with you more

 

lak

 

but hey, lets not complicate it too much eh

[Farsight]

When the atoms in the end of the metal bar gets "frozen" or "glued" will they still be able to mediate the nuclear forces necessarily to keep the bar together, in one piece, to the rest of the bar still outside?

 

No. The portion of the bar that touches the event horizon can't really be described as "bar" any more. For one thing it's been flattened to zero height because of the radial length contraction.

 

But the gravity just above the horizon is stronger than the nuclear forces so it doesn't much matter. The spaceship can't drag the end of the bar across the "surface" of the event horizon, the bar bends instead. If the bar is fairly brittle it will snap quickly, if it's more malleable it will stretch first like toffee before it snaps.

[Spyman]

No. The portion of the bar that touches the event horizon can't really be described as "bar" any more. For one thing it's been flattened to zero height because of the radial length contraction.

If a part of the bar is "flattened to zero height" wouldn't that create a gap in the bar ?

 

But the gravity just above the horizon is stronger than the nuclear forces so it doesn't much matter.

During the moment of closest approach the spaceship and the bar could be in freefall...

 

EDIT:

It's simple. You're in the box. There are no windows. You're in freefall. You chuck a ball across the inside of the box and it goes straight as a die, bounces off the side, and back into your hand. You are in an inertial reference frame. You can feel no gravitational force, and you can detect no gravitational force acting upon the ball.

During freefall the spaceship could with high enough speed, (below c), still avoid the EH and later on start the engines and change course to a safer place.

Well, I might be wrong here but outside of the EH, (for light), the stairs mentioned before should still work. So with a very large, billions of solar masses, BH, the tidal forces at the distance of the EH would be weak and thus the pilot in a powerfull spaceship passing by in a reasonable trajectory at very high speed, could be almost in freefall.

The spaceship is NOT supposed to hoover, at standstill, above the EH.

(It passes the BH close and outside of the EH with very high speed.)