The Naked Scientists

The Naked Scientists Forum

Author Topic: From neutron star to Black Hole...........?  (Read 24946 times)

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #25 on: 17/04/2009 21:55:23 »
Quote from: yor_on
Looking on it like that it makes sense in believing that Black holes is formed at the beginning of spacetime, as we can't really have 'super vacuum cleaners' eating up all 'matter/mass'. that as if matter never reaches that 'dimensionless' point 'spacetime' will have a certain density?? Otherwise it seems to me like the universe would loose matter and? What about the law of conservation if so??

I suspect that we will eventually find some principle of nature that prevents matter being condensed down to a singularity. My feeling is that singularities are not normal in nature. One thing I can think of is the composition of matter. Just exactly what is mass. We like to think of it as hv/cc plus momentum. It seems to me that a black hole would take away the v, leaving only constants. That should make it difficult to conserve massivness, which a black hole is supposed to do.
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
From neutron star to Black Hole...........?
« Reply #26 on: 17/04/2009 22:14:17 »
There's a point here where I can't connect the two ways of thinking of a black hole.

On the one hand, you can calculate the maximal pressure exerted by the Pauli exclusion principle and figure out how much gravitational pressure you need to overcome that.  In this argument, the black hole limit is set by the point at which gravity overcomes all other quantum pressures.

On the other hand, you can just look at the mass of a Schwarzschild-object and calculate its event horizon.  If the entire object falls within its event horizon, then you have a black hole, since nothing inside this event horizon can communicate with anything outside of it, and anything inside will inevitably move towards the singularity.  (For rotating black holes, you have a different kind of event horizon, and I have no idea if you can make the same arguments.) In this argument, you simply need to know the density of the object and general relativity instantly tells you where the singularity is.

One of these arguments compares gravity to quantum effects to give you a black hole limit, and one just requires you to know gravity... so how do they relate to each other?
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #27 on: 17/04/2009 22:42:41 »
Yep Vern, maybe there are such a principle. The thing about the Schwarzschild metric seems to be that there is no un-spinning Black holes found? Am I right there??

If you add the framedragging caused by spinning very massive something something :) then the space around such a object must be very strange. And it seems also a good proof of that nothing 'existing inside' spacetime ever reaching 'c' (ah, except light, that is). But its also very strange in that we can't expect it to be 'fermions' any longer inside that event horizon, if we assume (dangerous word that one) that it will have some sort of 'dimensionless point' to it. So what we have if so is something super massive, not consisting of anything known, rotating near 'c' and working both as 'gravity', and also as 'relative mass' due to its spinning. Seen as such it's Lightarrows example of light having 'mass' come through :)
« Last Edit: 17/04/2009 22:47:40 by yor_on »
 

Ethos

  • Guest
From neutron star to Black Hole...........?
« Reply #28 on: 17/04/2009 23:11:16 »
I remember reading scientific articles which suggested that when a Black Hole forms in our frame of space and time, a White Hole is produced elsewhere. I'm sure this is just speculation without much supporting evidence. Nevertheless, it is an interesting scenario. This has raised another question that you fellows may be able to shed some light upon.

If a White Hole is created along with Black Hole formation, is it not also possible that this presumed White Hole is not just elsewhere in our universe, it may have been displaced into a different time frame. Even more curious is the possibility that this White Hole may have traversed into a different dimension. This may explain the discrepencies with regard to the conversation of mass.

What do you fellows think??

.................Ethos
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #29 on: 17/04/2009 23:19:20 »
You know Ethos, it would be so much simpler if what we call Black holes instead would be 'White holes'. Which takes me to my question of today/night :)
How can we differ between them, observing those objects in Space? Is there anyone who can explain that in simple terms to me? That as I understand both of them, from our frame of reference, to attract mass?
 

Ethos

  • Guest
From neutron star to Black Hole...........?
« Reply #30 on: 17/04/2009 23:30:12 »
That as I understand both of them, from our frame of reference, to attract mass?
I'm not familiar with that point of view. I was under the impression that a few scientists had proposed that quasars were likely candidates for White Holes. As the amount of energy being released from these objects was well above what anyone had expected. That being the case, some had theorized that these quasars were expelling matter and energy to such a high degree that the only compatable explanation would be that they were exit points for the masses found in Black Holes.
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #31 on: 17/04/2009 23:31:33 »
It doesn't work for me that a white hole, whatever that is, would be created alongside a black hole. I haven't yet mastered the concept of a black hole. I can't get past the concept that we have a singularity that can somehow conserve massiveness. To me it just don't compute. :)
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #32 on: 17/04/2009 23:36:10 »
Quote from: Ethos
That being the case, some had theorized that these quasars were expelling matter and energy to such a high degree that the only compatable explanation would be that they were exit points for the masses found in Black Holes.
I like this idea, but I would simplify it. Maybe our supposed black holes radiate all the mass they accumulate in a ray parallel to the plane of their accretion disks. When we happen to be in the line of fire, so to speak, we see a massive amount of radiation. It might look a lot like a quasar.
 

Ethos

  • Guest
From neutron star to Black Hole...........?
« Reply #33 on: 18/04/2009 00:21:04 »
I like this idea, but I would simplify it. Maybe our supposed black holes radiate all the mass they accumulate in a ray parallel to the plane of their accretion disks. When we happen to be in the line of fire, so to speak, we see a massive amount of radiation. It might look a lot like a quasar.
Interesting...........Let's take this idea and run with it for a while.

Assuming that the accretion disk is responsible for quasars, and taking note of the time sequencing of these events, one has to ask the following question:

We have in the center of our galaxy a presumed Black Hole. In fact, it has become a rather common and reasonable assumption that just about every galaxy of any normal size has one at it's center. And these galaxies in question are believed to be very old, much older than the quasars. The bulk of quasar activity is believed to be from very early formations shortly after the Big Bang. That being said; If we are seeing two representations of the same object, as Vern has suggested, and understanding the vast time differential between the two, we may be observing a time loop of sorts. Could this be evidence for a steadystate universe? Mind you, I presently hold to the standard model myself but this question does make one think, doesn't it?
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #34 on: 18/04/2009 00:23:40 »
That as I understand both of them, from our frame of reference, to attract mass?
I'm not familiar with that point of view. I was under the impression that a few scientists had proposed that quasars were likely candidates for White Holes. As the amount of energy being released from these objects was well above what anyone had expected. That being the case, some had theorized that these quasars were expelling matter and energy to such a high degree that the only compatable explanation would be that they were exit points for the masses found in Black Holes.

"In astrophysics, a white hole is the theoretical time reversal of a black hole. While a black hole acts as a vacuum, drawing in any matter that crosses the event horizon, a white hole acts as a source that ejects matter from its event horizon. The sign of the acceleration is invariant under time reversal, so both black and white holes attract matter. The only potential difference between them is in the behavior at the horizon."
http://en.wikipedia.org/wiki/White_holes

"Yes, the matter that the white hole spits out is attracted to the hole. So is Hawking radiation, but it escapes to infinity anyway. To understand where the distinction between black and white holes comes from, consider the graph of r(t) = \sqrt{k + (ct)^2} for different values of k. (c is the speed of light and r is a kind of radius.) For k > 0 this is a nice smooth curve (half of a hyperbola). This is the surface of an ordinary gravitating spherical object in Kruskal-like coordinates. For k = 0 it reduces to r = | ct | , which has a sharp 90-degree turnaround in the middle where r(t) goes from "inward at the speed of light" to "outward at the speed of light." The inward half is the white hole horizon and the outward half is the black hole horizon. All of the usual "black hole" solutions to general relativity (like Schwarzschild and Kerr) are really gray holes with both black and white hole horizons in them. More realistic classical models have only the black hole horizon. But the whole business seems rather artificial -- maybe the correct description is more like the k > 0 case, where the white-black distinction is inherently absent. Hawking radiation makes this more plausible -- maybe it is the time reversal of absorption in quantum gravity. -- BenRG 23:55, 1 December 2007 (UTC)

        Black holes attract matter, which passes through a wormhole and exits via a white hole. However, Einstein's gravitational field equations only predict this if the mass of the black hole is 0, which is obviously impossible since black holes form from star collapse. Also, if anything with any mass enters a massless black hole, its associated wormhole and white hole will immediately cease to exist. In other words, white holes don't exist. --Bowlhover 16:12, 2 December 2007 (UTC)

I don't see the article on white holes, saying they don't exist. Before we can say something exists or not, it has to be accepted in the scientific community. 64.236.121.129 15:33, 4 December 2007 (UTC)"

------

It wouldn't be simpler would it :)
Then we should have an increased density I presume?
Or?

------Quotes--

What is a white hole? (Karen Masters, 2002)
The short answer is that a white hole is something which probably cannot exist in the real universe. A white hole will turn up in your mathematics if you explore the space-time around a black hole without including the star which made the black hole (ie. there is absolutely no matter in the solution). Once you add any matter to the space-time, the part which included a white hole disappears.

What would a white hole look like if it did exist?
The people/person who came up with the term 'white hole' was actually being quite literal. A white hole is pretty much like an 'anti-black hole'. A black hole is a place where matter can be lost from the universe. A white hole is a place where (if it could exist with any matter in it - which it can't) matter would pop out into the universe. This has many similarities to the Big Bang singularity.

Something Interesting to think about
It has been suggested by Stephen Hawking that once quantum effects are accounted for, the distinction between black holes and white holes is not as clear as it may seem. This is because of Hawking radiation which shows that black holes can lose matter. A black hole in thermal equilibrium with surrounding radiation might have to be time symmetric in which case it would be the same as a white hole. This idea is controversial, but if true it would mean that the universe could be both a white hole and a black hole at the same time. Perhaps the truth is even stranger. In other words, who knows?

-------End---

« Last Edit: 18/04/2009 01:21:36 by yor_on »
 

Offline LeeE

  • Neilep Level Member
  • ******
  • Posts: 3382
    • View Profile
    • Spatial
From neutron star to Black Hole...........?
« Reply #35 on: 18/04/2009 00:47:09 »
There's a point here where I can't connect the two ways of thinking of a black hole.

On the one hand, you can calculate the maximal pressure exerted by the Pauli exclusion principle and figure out how much gravitational pressure you need to overcome that.  In this argument, the black hole limit is set by the point at which gravity overcomes all other quantum pressures.

On the other hand, you can just look at the mass of a Schwarzschild-object and calculate its event horizon.  If the entire object falls within its event horizon, then you have a black hole, since nothing inside this event horizon can communicate with anything outside of it, and anything inside will inevitably move towards the singularity.  (For rotating black holes, you have a different kind of event horizon, and I have no idea if you can make the same arguments.) In this argument, you simply need to know the density of the object and general relativity instantly tells you where the singularity is.

One of these arguments compares gravity to quantum effects to give you a black hole limit, and one just requires you to know gravity... so how do they relate to each other?

I see working with the Pauli exclusion principle and quantum pressures as giving you an explanation of why a black hole forms, whereas working with the Schwarzchild solution just tells you the consequences of that event occurring, but doesn't attempt to explain why; it just says that in these conditions, this will occur.

The Schwarzchild solution really just says that something must happen as a consequence of 'c' being exceeded somewhere, whereas the QM solution goes a bit deeper into it.  I think this example really typifies why QM is the dominant theory - it attempts to go further/deeper than Relativity.
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #36 on: 18/04/2009 01:30:44 »
Quote from: Ethos
Could this be evidence for a steadystate universe? Mind you, I presently hold to the standard model myself but this question does make one think, doesn't it?
There seems to be a growing number of physicists willing to entertain the notion of a steady state universe. It will be interesting to see how it finally comes down. But I don't expect to live long enough to see the resolution. :) In the meantime, we can only play with the toys we have. Those are the Big Bang theory and Black Holes.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #37 on: 18/04/2009 02:45:33 »
They are mighty big toys Vern :)
And even better, they take no room ::))
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
From neutron star to Black Hole...........?
« Reply #38 on: 18/04/2009 05:16:25 »
I see working with the Pauli exclusion principle and quantum pressures as giving you an explanation of why a black hole forms, whereas working with the Schwarzchild solution just tells you the consequences of that event occurring, but doesn't attempt to explain why; it just says that in these conditions, this will occur.

The Schwarzchild solution really just says that something must happen as a consequence of 'c' being exceeded somewhere, whereas the QM solution goes a bit deeper into it.  I think this example really typifies why QM is the dominant theory - it attempts to go further/deeper than Relativity.

Well I guess part of the question is this: is the concept of an object falling within its own event horizon equivalent with gravitational collapse?  I'm guessing the answer is yes, due to the way things behave inside the event horizon (they have to collapse inward).  I'm also guessing, though I've never seen a proof, that long before you add enough mass so that an object falls within its own event horizon, its already gone past the point of gravitational collapse. 

After reading this question, I went back to some notes from when I took a course on general relativity.  We derived the Schwarzschild solution and then stated that because of how things behave on each side of the event horizon, this has to be a "black hole."  Then we justified the existance of a black hole by looking at the masses that would be required for a black hole to form via gravitational pressure considerations, but we never linked the two.
 

Offline om

  • Full Member
  • ***
  • Posts: 53
    • View Profile
From neutron star to Black Hole...........?
« Reply #39 on: 18/04/2009 05:58:22 »
Quote
I suspect that we will eventually find some principle of nature that prevents matter being condensed down to a singularity. My feeling is that singularities are not normal in nature. One thing I can think of is the composition of matter. Just exactly what is mass. We like to think of it as hv/cc plus momentum. It seems to me that a black hole would take away the v, leaving only constants. That should make it difficult to conserve massivness, which a black hole is supposed to do.

Detailed studies of the properties of ordinary nuclei have already revealed strongly repulsive interactions between neutrons that prevent the formation of black holes.

[See: "Neutron repulsion confirmed as energy source", Journal of Fusion Energy 20, 197-201 (2003)].

http://www.omatumr.com/abstracts2003/jfe-neutronrep.pdf

Furthermore, these studies show that neutron-emission from a neutron star "may release up to 1.1%-2.4% of the nuclear rest mass as energy".  By comparison, only about 0.8% of the rest mass is converted to energy in Hydrogen fusion and only about 0.1% of the nuclear rest mass is converted to energy in fission.

Therefore massive, energetic celestial objects are not black holes at all, but neutron stars that are highly energized by repulsive interactions between neutrons.

With kind regards,
Oliver K. Manuel
http://www.omatumr.com/
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #40 on: 18/04/2009 10:14:45 »
If one presume that a white hole is very alike a Black one, then it too will have a 'point' of gravity inside it. That 'point' can't be fermions any longer. If it is so then what it might be trying to 'spew' out would be 'pure mass' whatever that will be. I'm guessing on something similar to bosons, but maybe not interacting with our spacetime as such. That is as if there exist something being of 'primary' constituents, that creates a Big Bang. If so then there is no problem with it from our point of view as it have been 'transitioned' into a state without interaction with us.

If that is possible then those 'white holes' could be what once created mass and space although they then must have been at another state of their formation. That would explain why we seem to find them in every Galaxy. There must be a reason to those 'super massive' gravity wells inside our galaxies. And yes, it's only a idea :)
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #41 on: 18/04/2009 16:00:50 »
If one presume that a white hole is very alike a Black one, then it too will have a 'point' of gravity inside it. That 'point' can't be fermions any longer. If it is so then what it might be trying to 'spew' out would be 'pure mass' whatever that will be. I'm guessing on something similar to bosons, but maybe not interacting with our spacetime as such. That is as if there exist something being of 'primary' constituents, that creates a Big Bang. If so then there is no problem with it from our point of view as it have been 'transitioned' into a state without interaction with us.

If that is possible then those 'white holes' could be what once created mass and space although they then must have been at another state of their formation. That would explain why we seem to find them in every Galaxy. There must be a reason to those 'super massive' gravity wells inside our galaxies. And yes, it's only a idea :)

I tend to speculate in the opposite direction. Instead of imagining new and more exotic realities, I imagine less and more simple realities. This finally took me to the realization that we can not prove by any experiment we can devise even with unlimited resources, that there exists any physical reality other than the electromagnetic field.

So we cannot disprove a notion that was widely held at the turn of the 20th century. That notion is:
The final irreducible constituent of all physical reality is the electromagnetic field.
« Last Edit: 18/04/2009 16:04:46 by Vern »
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #42 on: 18/04/2009 23:24:16 »
Vern, why so prosaic?
Life is filled with mystery's.

Like, where my glasses have gone?
:)
 

Offline LeeE

  • Neilep Level Member
  • ******
  • Posts: 3382
    • View Profile
    • Spatial
From neutron star to Black Hole...........?
« Reply #43 on: 18/04/2009 23:41:44 »
Well I guess part of the question is this: is the concept of an object falling within its own event horizon equivalent with gravitational collapse?

Hmm... good question.  I'll play devil's advocate and say no, because gravity may not be the only means by which an object may be compressed so that it lies entirely within its Schwarzchild radius; pressure could be applied externally to cause the compression (I'm thinking of things like explosive compression, where an explosive shell surrounding an object explodes inwards as well as outwards, or some other ideas I've heard about, using lasers to compress minute amounts of matter).  In these cases, gravity only becomes a 'special' factor after the BH has formed.

Just playing Devil's advocate though - I don't really have an opinion/answer on this.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #44 on: 19/04/2009 02:12:38 »
So is there any 'constant' number for this?
Compression ratio relative its size/density. As the idea seems to go out on that no matter how small or big or dense it (that particle/matter) is, there will always be a 'magic' moment where its compression then will force it into a 'Black hole'??
« Last Edit: 19/04/2009 10:22:12 by yor_on »
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #45 on: 19/04/2009 17:57:59 »
I recently read of a study that concluded that a black hole could not form out of an accretion disk because of the spinning action. If so that would only leave the exploding star scenario. I can't find the link right now; I think it was from a link posted by yor_on a few days ago.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
From neutron star to Black Hole...........?
« Reply #46 on: 19/04/2009 18:22:59 »
Here is another link, only a computer simulation though.
http://www.sciencenews.org/view/generic/id/37200/title/No_naked_black_holes
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #47 on: 19/04/2009 18:38:21 »
Quote from: yor_on's link
Mathematically, “naked” singularities, or those without event horizons, can exist, but physicists wouldn’t know what to make of them. All known mechanisms for the formation of singularities also create an event horizon, and Penrose conjectured that there must be some physical principle — a “cosmic censor” — that forbids singularity nakedness, explains coauthor Emanuele Berti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We hope it’s true,” he says of the cosmic censorship hypothesis, “because it basically hides the failures of general relativity behind the event horizon.”
Hey; I think I found the cosmic censor.  ;D
Quote from: my thread in the new theories forum
An example of pure speculation leading to something that may have more wide ranging implications is the contemplation of how gravity might affect gravity in the formation of a black hole. Since time is part of the equation for gravitational acceleration and time is dilated in strong gravitational fields, gravitational acceleration must also be reduced in strong gravitational fields.

Then this fact might be useful in understanding the anomaly we see in some galaxies where the outer stars move too fast. The effect described above would cause a gravitational depression toward the centre of massive galaxies. There would be a halo effect where more gravity than expected would concentrate in the outer reaches of the galaxy.
« Last Edit: 20/04/2009 00:41:03 by Vern »
 

Offline Vern

  • Neilep Level Member
  • ******
  • Posts: 2072
    • View Profile
    • Photonics
From neutron star to Black Hole...........?
« Reply #48 on: 20/04/2009 16:59:24 »
Quote
Since time is part of the equation for gravitational acceleration and time is dilated in strong gravitational fields, gravitational acceleration must also be reduced in strong gravitational fields.
Okay; somebody modify the equation for gravitational acceleration to include this and dust off a spot on your mantel for the Nobel. :)
 

Offline litespeed

  • Sr. Member
  • ****
  • Posts: 419
  • Thanked: 1 times
    • View Profile
From neutron star to Black Hole...........?
« Reply #49 on: 28/04/2009 06:07:34 »
I've been asking whether neutron stars can become black holes in other forums, but this one is the best so far. However, I do not see where Plank Units have been discussed. Since I do not believe in singularities, it seems to me a black hole would include, at its center, an empty volume with the diameter of one plank unit.

In one of the other forums I asked some questions on relativity. 1) as matter accelerates into a BH does it gain mass? 2) As it approaches the speed of light does time come to a virtual halt?

Newbee Novice

 

The Naked Scientists Forum

From neutron star to Black Hole...........?
« Reply #49 on: 28/04/2009 06:07:34 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums
 
Login
Login with username, password and session length