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Author Topic: Once a Blackhole has been fed, should it not always remain visible?  (Read 4585 times)

Offline Airthumbs

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So, from the perspective of an observer something entering a Blackhole slows down until at the point it crosses the Event Horizon it appears to come to a standstill.  If that's the case then we, as the observers, should essentially always see the evidence of a Blackhole having fed by the accumulation of paused superheated matter emitting light in x-ray at site of the Event Horizon?  ::)


 

Offline Jabulon

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i think a black hole means that the gravitational pull itself has become so strong, that even light cant escape it, so no light can be reflected from it. Much like the color black doesnt reflect color, a black hole, wouldnt reflect any visual wavelength. Nothing detectable actually, as the gravitational pulls are so strong, that they literally get sucked into it.

im not an expert, but i think thats the answer ur looking for.

pls correct me if im wrong.
 

Offline yor_on

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Think of it as everything 'pointing' somewhere. Everything you see is a result of 'radiation bouncing'. When it comes to a Black Hole the light have only one way to go, the reason being the Event Horizon that 'cuts' all that 'bouncing' off. Before that you might get a weak 'reflection' of light as it could 'bounce' on the stuff falling in, but to be noticeable for us I guess that the light 'bouncing' will need to be quite intensive the closer it bounce to the Event Horizon.

After passing the Event Horizon the gravity makes it impossible for any light to 'bounce' back. Hawking radiation postulates a radiation on the EV (event horizon) Due to the energy involved you see a lot of spontaneous 'pair productions'. The idea is that the the negative 'twin' annihilate the positive particle it meets inside the EV, and the positive then 'wander' in SpaceTime. If a positive particle falls in the negative can't survive outside since 'a negative-energy particle can't continue to exist outside the horizon for a time longer than h/E. So the black hole lose energy to vacuum fluctuations, but can't gain energy.'

And that's also the idea of 'information' communicating through the Event horizon as pair production implies an entanglement which then makes the 'negative' particle communicate its state to the positive as it annihilates inside the EV.

You can see this two ways. Either an Entanglement has no limitations as we are discussing 'singularities'. And there you can as easily consider worm holes. Or the information is not 'meaningful' other than as 'energy quanta'. What you might argue against it is that an particle anti particle annihilation is expected to leave positive rest products. That should mean that the Black hole won't decrease proportionally to SpaceTime gaining? But I'm not sure on that one as the same could be said for all particle/anti particle annihilations inside SpaceTime too?

The resultant energy is the rest of the pair production, after the negative particle is 'eaten' by a positive inside the EV. And the information 'leaked' is the 'spin' that then will have to be set as it's 'other half' got 'eaten'.

Makes me head spin that one does. And without preamble over to wild guesses :)

Because if it's true then I can't see any problem sending energy between 'parallel universe'. We already know that plants do it, by entanglement and somewhere I saw a proposition for testing sending energy through entanglements. It builds on the concept of a black hole as a 'singularity' of course. But if that is true, then we have a way to send 'energy' through the Event Horizon, and also a 'worm hole' if we like. Furthermore it's possible to assume such radiation already existing if so, maybe made by some more advanced culture.

And that's another reason for why we might need to split the concept of 'information' and 'meaningful information' just as we assumed that entanglements couldn't carry 'information' before. It's interesting. Maybe it can carry 'information' if it can carry 'energy'? But maybe not making it 'meaningful', depending on how we want to define that?

Still?
Isn't energy 'meaningful'??
Ask a plant :)
« Last Edit: 26/12/2010 14:35:48 by yor_on »
 

Offline yor_on

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Or maybe not?
As positive energy get killed so quickly?
Inside a Event horizon?

But if we then found a source of positive energy constantly expiring?
Sounds very alike 'quantum fluctuations' if so btw :)
 

Offline Bill S

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Interesting as the above comments are, I am not sure that they really address the question in the OP.

Looking through my past notes I find a similar unanswered question.
 
  Spacetime distortions predicted by relativity seem to suggest that any body, any fragment of cosmic debris, that has ever (in its own frame of reference) fallen through an event horizon into, for example, a black hole, must, in the frame of reference of any outside observer who stops to look, be still stuck at the event horizon.  The entire accretion history of a black hole since the formation of its event horizon should be visible to any observer whose technology allows him or her to manoeuvre into the right position.  Of course, an observer will see these things by virtue of the light reflecting from them, but because the objects will not have crossed the event horizon, in the observerís F of R, this should not be a problem.   Strange as this might seem, it is even stranger to realise that, outside the frame of reference of the observer, all this material is not there, because it has long since plunged down the ever steepening  gravity well into the depths of the black hole. 
 

Offline Airthumbs

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Bill S, thanks for confirming exactly what I was thinking.  The reason behind my question is that there exists Blackholes with no accretion disks, the so called silent Blackholes.  A popular theory at present is that Blackholes go through a cyclic process of matter accumulation.  What I am getting at is that this cannot be the case as once they have "fed" the evidence for this will always remain in the form of the accretion disk.  So a silent Blackhole according to current theory has either never encountered matter in it's history or, dare I say it, there is a fundamental problem in our understanding of event horizons and/or accretion disks?
 

Offline Soul Surfer

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This obsession about objects in theory being always visible on an event horizon annoys me.  It is another of those "gee wiz" things that science writers like to spice up their presentations and gives people the completely wrong idea.

Let me explain consider an old fashioned tungsten filament electric light bulb.  Say a car headlamp bulb.  It is switched on and glows brightly and you can see it clearly.  You switch it off and the light goes out but quite slowly because you can see the filament cooling down.  If you look at the filament a few minutes later with an infra red thermal detector you may be able to detect that it is still quite warm a good deal hotter than the environment so you know it has been switched on recently.  if you carefully measured the resistance of the filament after a few hours you may still be able to detect that it is above the environmental ambient.   If you consider the mathematical theory it is a slow asymptotic decay and the temperature never actually does reach the ambient temperature mathematically but no one makes a fuss about it because lots of things in real life have asymptotic decays.

This fading of images on the event horizon of a black hole is just like this an asymptotic decay and probably quite a quick one (I have not been able to find out the likely time constant of this decay yet) but nothing special an there is no reason to make a fuss about it.   
« Last Edit: 27/12/2010 14:57:10 by Soul Surfer »
 

Offline Bill S

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Quote from: SS
This fading of images on the event horizon of a black hole is just like this an asymptotic decay and probably quite a quick one (I have not been able to find out the likely time constant of this decay yet) but nothing special an there is no reason to make a fuss about it.

This sounds like another case of Zeno's paradox.  I shall adjust my notes accordingly. Thanks.   
 

Offline Airthumbs

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I prefer the explanation of SS and it does seem illogical that given an observers perspective energy from objects passing into a Black hole should remain for infinity at the site of the Event Horizon. This also does add strength to the cyclic behaviour of eating habits for Black holes returning to a state without an accretion disc.
 

Offline yor_on

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Well, I guess it depends on how we define what 'times arrow' is.
Myself I define it as something belonging to a 'room time geometry'.
And everything existing that you will be able to touch, as radiation & matter, I expect to have its own?

If looked at this way, when you're watching this guy 'freeze' he really does so, from your 'room time geometry' that is. But in his own he's 'free falling', time ticking as always, and will reach whatever there is in a for him measurable time, tidal forces ignored.

Which then makes 'times arrow' into a local phenomena, even though not noticeable as such as we all find ourselves able to 'communicate', or observe, what we agree to be our 'common SpaceTime'.

It's as all other things, a matter of personal taste:)
I like it.
==

What I mean by 'not noticeable' is that you will find SpaceTime to be a 'whole experience' all times you care to observe it, no matter your 'frame of reference'. Against that one might point out that we do know, when comparing 'events', we will disagree if the frames are too dissimilar, due to mass or motion/acceleration. But when doing so you go outside your own frame of reference, cerebrally comparing it to what you won't be able to confirm other as an 'second hand observation' (Someone else's 'frame of reference').

So there is a difference between your own observations and 'physics' :)
===

Also, as we all 'communicate' by radiation, one form or another, Soul Surfers point is a valid one.
« Last Edit: 27/12/2010 18:19:02 by yor_on »
 

Offline CliffordK

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I prefer the explanation of SS and it does seem illogical that given an observers perspective energy from objects passing into a Black hole should remain for infinity at the site of the Event Horizon. This also does add strength to the cyclic behaviour of eating habits for Black holes returning to a state without an accretion disc.
Ok,
So the event horizon is the point where the speed of light and gravity becomes equal.  And, thus no more light is able to escape.

Just before the object reaches the event horizon... light generated by the object, or light reflected by the object would appear to come to a standstill. 

Now, if we believe in the packet (photon) concept of light, as well as the constant speed of light in "normal space".  Then when the light reflected from the object reaches normal space, it should resume the speed of light.

Now, say the object releases a billion photons a second in normal space.  That billion photons per second will be expanded indefinitely.  Say if it is visible for a billion seconds, the the release rate drops down to 1 photon per second, and give the perception of a much lower intensity light (fading away as stated above).
 

Offline Bill S

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Quote from: yor on
a 'room time geometry'

Is a 'room time geometry' anything like a frame of reference?
 

Offline yor_on

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Yeah, it's the same, it's mostly for my own benefit I use it. To make me remember that I'm speaking of the unique 'room' I live in with a specific 'time'' that even though other 'frames of reference' may find varying, to me always 'tick' the same. And 'geometry' because that is what can change for me personally. My time won't change, even though the universe's might seem to do so in a accelerated motion.

I've used 'frames of reference' before, the problem being that it is a very neutral definition, you can talk about your own, then about someone else's in the same breath fooling yourself to see both as being of the same 'value'.

They're not, no matter what you do, how fast you travel, if you're at a neutron star, you have the same expiration date. But all other frames you ever will notice, or as I call it 'room time geometries' are relative you open for 'change', and by the same 'experiences' that you will find 'not' changing your duration. If you see how I think.

When I use my description I know where I stand with it, I'm looking at the universe from my 'room time geometry' and mine is unique. If discussing yours then that one also will be unique, solely yours.

There is a subtle difference in it to me :)
Helping me to see what I think is important. People seem to think that this universe is a seamless 'whole', and I agree in one way, but if you look at it as 'room time geometries' they seem to come in all 'sizes' from a pebble on the beach to a electrons 'orbital' to, whatever I can think up i guess :) And they all have to be slightly different I think, but still giving us all this feeling of 'sharing' the exact same universe.

We don't.
But, we do:)

Can you be more 'zen' than that ::))
 

Offline yor_on

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And what seems to bind them together is, as Soul Surfer pointed out, radiation.
Gravity too naturally, but gravity is not a 'force' to me, it's more of a topology.

Maybe there are some more effects I should consider but radiation and gravity, or 'potential gravity' as it is called when defining where the topology really peaks and bumps :) seems to cover most of it. After all, radiation is also 'virtual', so it follow us up and down all 'sizes' there is.

And 'matter' of course, aka invariant proper rest mass. That's also there but how that and what that is? Maybe that's as big a mystery as photons, well to me at least:)
 
« Last Edit: 29/12/2010 14:08:12 by yor_on »
 

Offline Bill S

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Thanks for the explanation yor_on; we probably all have our particular terminology that we find helpful in sorting out our ideas.  I may have mentioned it before, but one thing I find helps me is to make the following distinctions:
Universe = the Universe that we experience. (always with a capital "U")
universe = any other possible universe.
Cosmos = everything that exists, or may exist. (does not necessarily have a capital "C")
 

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