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Author Topic: Can Black Holes initiate matter creation?  (Read 15426 times)

Offline Alan McDougall

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Can Black Holes initiate matter creation?
« Reply #25 on: 15/08/2008 15:36:38 »
Graham,

I was just kidding! who does not make spelling mistakes especially myself who also constantly makes key errors. I think the internet jargon for this is "Fat Fingered'

Thomas Jefferson a notorious mispeller said anyone can spell correctly, it takes talent and creativity to misspell words like he did.

It just goes to show that you have a colourful creative mind, I meant no offence

Regards

Alan
 

Offline graham.d

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Can Black Holes initiate matter creation?
« Reply #26 on: 15/08/2008 15:45:46 »
He he. No offence taken. Good grief, my skin is a bit thicker than that :-)
 

Offline LeeE

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Can Black Holes initiate matter creation?
« Reply #27 on: 16/08/2008 14:08:12 »
I think that time dilation is a very important factor because it will affect all of your local energy calculations.  For example, if you're orbiting a BH at the radius where the rate of time due to gravity induced time dilation is 0.5, you will perceive yourself completing an orbit in half the time that an infinitely distant observer would measure, and thus seem to be traveling twice as fast, which then has implications for your perceived orbital distance i.e. you'd see yourself orbiting more closely.  The distant observer, on the other hand, will just see an apparent mass increase and foreshortening.

I don't think that the distance from which the object falls is necessarily the most important factor here, and neither by inference is it's speed.  There's nothing to stop us from accelerating, or decelerating the 'falling' object by using a rocket booster or retro thrust.  Using retro thrust to slow the falling object would allow the object to be traveling much slower than it's free-fall speed as it approaches the BH, and given sufficient thrust the object could be held stationary above the BH.  The length contraction and mass increase factors would then be zero i.e. unchanged, but the gravitational time dilation factor would still be present and would affect your calculations regarding how much fuel you perceive you're burning to maintain your stationary position.

That's an interesting point regarding how a closely orbiting body would see the BH, or rather the EH, as it would have to be orbiting outside the EH.  If your local rotation period is equal to the orbital period, so that you're always facing the BH, it, as a point source, wouldn't be appearing to move at all.  But then you can't see the BH itself, only the EH, which as you pointed out earlier, isn't an actual surface.  However, if you should see other objects falling in to the BH as you orbit around it, you'd see the length contraction and mass effects upon them.  Once again though, the events you'd see would appear to happen more quickly because less time has passed for you.

What I'm wondering now is how would relativistic orbital speed time dilation factors combine with gravitational time dilation factors?
 

Offline graham.d

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Can Black Holes initiate matter creation?
« Reply #28 on: 16/08/2008 20:44:25 »
I was discounting time dilation effects as I was only considering the view of the person falling and not that of any other view from a distant place and/or different frame. The  reason for considering just a free falling object was to avoid the difficulty of adding the extra complication of other specific "events" like an acceleration. You are quite right that you could slow down using rocket motors (for example). You could suspend your fall into the BH for a period of time, as long as you were outside the theoretical EH, and even accelerate away with sufficient fuel available. It would be valid to consider what the BH would look like from such a viewpoint. There would be no relative motion with respect to the BH but there would be the huge gravitational field and that you would be a long way down the gravitational well.

The orbital situation gives both velocity and a gravitational time dilation with respect to distant objects. These will add so that your clocks will run slow when seen by a distant observer. From your perspective the universe outside will be blueshifted because you are in a gravity well, but you are moving with respect to distant objects (they are moving relative to you) so their clocks should run slow. The two effects are in opposition but there is no reason why they should cancel. At least, I don't think so.

Is there anyone out there who fancies doing the maths for these situations? :-) I expect some of these may not have solutions except via simulation.
 

Offline LeeE

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Can Black Holes initiate matter creation?
« Reply #29 on: 17/08/2008 15:17:46 »
I think the problem with only considering the point of view an observer falling in to a BH is that from their point of view they can never reach the EH.  From such a point of view, nothing can fall in to a BH, which seems to be false.

I have to say seems to be because there's the issue of the rate of time becoming zero at the EH, and physics as we understand it cannot explain how anything can happen in zero time i.e. if the rate of time at the EH is zero, how can anything move below the EH when there is no time for anything to happen?

I can't see any reason for the gravitational and speed time dilation effects to cancel - for this to happen you'd need to be able to accelerate time, which can't be done - the fastest rate of time is 1, which can only actually occur in no gravitational field and at zero velocity, and which can only apply to the hypothetical infinitely distant observer.

I thought I'd have a look at some of the numbers so I've done a simple spreadsheet to calc the Schwarzschild Radius (Rs), the rate of gravitational time dilation at the Rs, Rs+1m & Rs+10m, the orbital velocity at Rs, Rs+1m and Rs+10m, and the time dilation factors at those orbital speeds, for a range of masses, for a circular orbit around a non-rotating spherical mass.  Assuming I've done it all correctly, it shows that the rate of time at the Rs is zero, but that the orbital velocity is well below 'c' (I'd assumed that it was 'c', without ever actually working it out - doh!).

www.spatial.plus.com/Gravitational_Time_Dilation.xls

It was created using OpenOffice.org under Linux, so I'm happy to assert that it's virus free, but anyone downloading this spreadsheet should virus check it for their own peace of mind.  I'd appreciate it if someone can verify it's correct - I make no guarantees.
 

Offline graham.d

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Can Black Holes initiate matter creation?
« Reply #30 on: 17/08/2008 19:08:12 »
Your equations are right I think but your conclusion that an observer falling into a BH never reaches (or crosses) an EH is not correct. To a distant observer an object cannot be seen to cross an EH, but to an observer who is actually falling in, this is not the case. His local space will be distorted but, if the BH were big enough, this distortion can be small enough that tidal effects may be negligible. He could cross the EH without even noticing. Although he may see a distorted universe if he looked out of a window. His "Proper Time" ticks would go to zero at the EH, as they would for anyone who approached the speed of light for example, but this relates to how his measured time passes with respect to other observers in different frames and not to how he sees the world locally. The meaning is more that he would see a distant observer's clock running very quickly and, ultimately, infinitely fast as the EH was crossed.
 

Offline LeeE

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Can Black Holes initiate matter creation?
« Reply #31 on: 17/08/2008 22:49:26 »
I'm afraid I still can't see how an observer who is inside the EH can experience any time passing because the time rate becomes zero at the Schwarzschild Radius, which isn't dependent upon the observer.  Although the spatial distortion of space-time might be a practical problem to our falling observer, I don't think we really need to consider it as a relevant factor here.

Quote
The meaning is more that he would see a distant observer's clock running very quickly and, ultimately, infinitely fast as the EH was crossed.

I agree with this totally, but the converse of the [falling] observer seeing the distant observer's clock running infinitely fast at the point where he crosses the EH is that his clock has stopped - no time passes for him from that point onwards, and he is effectively frozen in time.  He cannot make any observations, or do anything, or experience anything inside the EH because there is no time for him to do it within.  So yes, he would not notice that he had crossed the EH, but he'd not notice anything else either.

Heh  :D - I think that all this talk of orbits has left us going around in circles and we really need some more informed input.
 

Offline graham.d

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Can Black Holes initiate matter creation?
« Reply #32 on: 18/08/2008 08:57:06 »
I think it is to do with the multiple definitions of time. What the observer at an EH would experience is all of his local environment's "proper" time slowing. He would continue to breathe and his heart would continue to beat in a normal way. A distant observer would see his bodily movements slowing to a standstill.

Googling shows a good summary:

http://cass.ucsd.edu/public/tutorial/GR.html

In particular:

http://casa.colorado.edu/~ajsh/singularity.html

All the other pages are a good read though and cover much of our discussion, including to some extent, your original question! It seems photons will orbit at 1.5R (R= Schwartzchild radius) and not at R.

There is quite a lot on the web - not all of it well informed - but I think this site is very good.

 
 

Offline LeeE

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Can Black Holes initiate matter creation?
« Reply #33 on: 18/08/2008 19:05:19 »
Thanks for the links - I'll have a look at those.  When I worked out the orbital velocity for the Schwartzchild Radius it was < 'c' and the orbital radius where the velocity = 'c' was inside the Rs/EH, not outside it.
 

Offline Gabe2k2

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Can Black Holes initiate matter creation?
« Reply #34 on: 11/09/2008 02:19:05 »
As I talked about in the forum thread

Is a black hole a point!

 The understanding of black holes is very wrong and simply put yes black holes are very creative perhaps every galaxy, Every solar system Every star is created by a body which resembles a black hole.
 

Offline Alan McDougall

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Can Black Holes initiate matter creation?
« Reply #35 on: 11/09/2008 03:20:46 »
Lee,

The changing or creation of matter from energy is a fascinating topic and is this not what they are attempting at the CERN Large Hadron (Proton) collide

Taking the energy from the collision of the protons to form mass/matter a reverse to nuclear Fusion in some sense

Alan
 

Offline LeeE

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Can Black Holes initiate matter creation?
« Reply #36 on: 12/09/2008 15:24:53 »
I wasn't thinking in terms of a BH creating matter or energy, just that they may provide a location where the conversion of photons to matter via collisions might be very high.

Specifically, I was thinking about the possibility of trapping many photons in a common orbit around a BH where collisions would then become very common, but once I worked it out it turns out that the orbital radius where the orbital velocity is equal to 'c' is less than the Schwarzchild radius, and therefore inside the Event Horizon, so the whole idea is wrong and I'm reminded to check things first instead of relying upon mistaken assumptions  [:I]
 

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Can Black Holes initiate matter creation?
« Reply #36 on: 12/09/2008 15:24:53 »

 

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