Gravity: The why and the how:

[Farsight]

This is, indeed, a point. The coordinates are fine, the metaphysical description in terms of a space flowing like a river is invalid.

Good stuff Schmelzer.

What would really happen, in the spacetime interpretation of GR, would be different.

There are two interpretations, which Kevin Brown mentions in The Formation and Growth of Black Holes. After reading Einstein talking about the speed of light varying with position, I conclude that the "other" interpretation is the correct one.

Say, A is on the horizon. Not for long, because he consists of usual matter. Thus, he would be infalling.

That's what people say. But note that the force of gravity at any one location relates to the gradient in the coordinate speed of light at that location. If you dotted optical clocks throughout a slice through the Earth and the surrounding space, then plotted the clock rates, you'd be plotting out the Riemann curvature depiction above. However the coordinate speed of light at the event horizon is zero, and it can't go any lower than that. So there's no gradient in the coordinate speed of light. And so no force of gravity.

Following the equivalence principle, he would not even know about this (except if the tidal forces would be too strong). Then, if he wants to measure some speed, he would try to create a local system of coordinates, stupidly with assuming himself being at rest. This would be a system of coordinates quite different from that with the light ray being at rest. In this strange, infalling system of coordinates the light would have, by construction, the speed c.

The moot point that this just can't happen in a place where the coordinate speed of light is zero. There's no falling down, and there's no light moving to define those coordinates. It's a strange place all right.

The GR spacetime interpretation may be rejected as stupid or unreasonable, if one likes, but not as inconsistent. It is quite consistent.

I don't think there's much of an issue with the GR spacetime interpretation myself. I think the issue is with "all coordinate systems are valid". IMHO people take this too far, and invent fantasy coordinate systems that just don't match Einstein's description of what a gravitational field is. Take a look at the picture below from MTW. On the left is a depiction of Schwarzschild coordinates. Most people take this for granted, but if you look closely, you'll appreciate that the vertical axis is the time axis, and that the infalling body goes to the end of time and back and is in two places at once. Hence Susskind's elephant, which I can confidently say is nonsense.

The Kruskal-Szekeres coordinates on the right effectively do a hop skip and a jump over the end of time. They "use a new time coordinate" which effectively puts a stopped observer in front of a stopped clock and claims he sees it ticking normally in his own frame. IMHO this is a schoolboy error. I am reminded of the dead parrot sketch.

 

[Farsight]

The river/waterfall model is mathematically validated and has been accepted by arxiv. Actually interesting that you decide to hop onto the crank bandwagon, considering that you claim your own "ether"paper by the same publisher predicts more than mainstream interpretation of GR. I smell some hypocrisy.

You abusive idiot. Einstein described space as the "ether" of general relativity. That's why arXiv is littered with papers that refer to Einstein-aether. Jesus H Christ, spare us from popscience trolls who believe in woo and who reject all education and references that challenge it.

 

[paddoboy]

James.., if general relativity is a description of a real gravitational field, which is where it, general relativity, began.., would that not mean that while we can learn from mathematically valid hypotheticals, that are not observed to represent any real gravitational field.., only solutions that do represent real gravitational fields are valid solutions?

All cosmologists are doing is modelling the gravitational field according to observations. If the model makes successful predictions and is not falsified, then you writing it off as hypothetical is rather silly.

And yes your statement above is technically accurate because even solutions that do not describe anything expected to be real, can be mathematically valid.

You dont believe the gravity field we all exist in is real?

The link to, http://jila.colorado.edu/~ajsh/insidebh/rn.html, has been used to validate the idea of a charged black hole and how it interacts with our reality. The problem is in the third paragraph into the link,

The big difference between a charged (Reissner-Nordström) and an uncharged (Schwarzschild) black hole is that the mathematical solution to the charged black hole has, inside its horizon, a one-way wormhole that connects to a white hole that propels you to another space and time. Sadly, the wormhole is violently unstable, and would not occur in reality. Click on Waterfall to learn more about why the charged black hole has a wormhole. Click on Realistic to see what happens in reality,​

The above seems to clealy state that the charged black hole does not exist in reality. Not that they are rare, that they do not exist!

When you misinterpret what Professor Hamilton has said, maybe you should also consider that the "No Hair theorem" is overwhelmingly accepted by mainstream cosmology. The "No Hair Theorem" of course is that a BH can have only three properties....that being mass, spin and charge, and both the latter two are negated over time.

Because these discussions include many different mathematically valid solutions, side by side (even intermingled), as descriptions of reality, there can be no expectation of ever reaching any consensus, in the argument... And I intentionally use the word argument, because much of the argument is directed at the posters rather than any specific discussion of a solution to EFE.

Any supposed consensus you speak of applies to sciforum.com only. It will not be a consensus that is embraced by mainstream cosmology in general.
In fact the recently concerted effort by known anti mainstream posters of various degrees of crankdom, makes any consensus here totally unlikely as you suggest. One even has claimed to have a TOE.
Your claim re arguments directed at posters rather than a specific issue is probably also valid, but again you need to remember that whatever doubt exists about mainstream "speculative" claims [which you prefer to highlight far more often than any opposing alternative claims] is the incumbent solution until something better comes along.
Your own place in all of this in my opinion appears to be having 2 bob each way, or sitting on the fence, and coupling that with your self confessed mission to be hard on me, could be interpreted as an agenda.

Please consider what I have said and examine the contents of your posts and your claims around certainty or lack thereof with regards to myself.
And please remember what past Professors have said, which you yourself have appreciated. Scientists/cosmologists are allowed to make reasonable assumptions based on already acquired knowledge and data.
That is done all the time, and this forum and I, do not really need you to keep reminding people of that.
Considering that with the facts that scientific theories do grow in certainty over time, perhaps you need to direct your doubts in the direction of the alternative brigade.

 

[paddoboy]

You abusive idiot. Einstein described space as the "ether" of general relativity. That's why arXiv is littered with papers that refer to Einstein-aether. Jesus H Christ, spare us from popscience trolls who believe in woo and who reject all education and references that challenge it.

And yet still its you that has been banned in numerous forums, and it is also you that has claimed to have a TOE. That says it all. The truth hurts.
Oh, and please calm down before you have a coronary.

 

[paddoboy]

There is something to object to the model.

Well then do it appropriatley and submit a paper pointing out what you believe are errors.
At least it has had a number of citations as distinct from your own ether paper.

 

[rpenner]

The Gullstrand-Painleve metric isn't valid because at the event horizon the coordinate speed of light is zero.

No it's not. It's $$c$$ in that metric.

Same space-time, two metrics under discussion means two coordinate systems. Each must be addressed separately.

In the Gullstrand-Painlevé metric (written in SI units): $$d\tau^2= \left(1-\frac{2GM}{c^2 r} \right)\, c^2 dt_r^2- 2\sqrt{\frac{2GM}{c^2 r}} c dt_r dr - dr^2-r^2 \, d\theta^2-r^2\sin^2\theta \, d\phi^2 $$, if we want to know the coordinate speed of light in a certain direction, we solve for $$d\tau^2 = 0$$, consistent with that direction.
Thus in the radial direction, $$d \theta = d \phi = 0$$, and we have $$dr = v dt_r$$.
Thus we solve $$0 = d\tau^2= \left(1-\frac{2GM}{c^2 r} \right)\, c^2 dt_r^2- 2\sqrt{\frac{2GM}{c^2 r}} c v dt_r^2 - v^2 dt_r^2 $$ which gives a quadratic equation for v:
$$v^2 + 2\sqrt{\frac{2GM}{c^2 r}} c v - \left(1-\frac{2GM}{c^2 r} \right)\, c^2 = 0$$
Thus $$v = \left( - \sqrt{\frac{2GM}{c^2 r}} \pm 1 \right) c$$ and when $$r = \sqrt{\frac{2GM}{c^2}}$$ the outbound radial coordinate speed is zero while the inbound coordinate speed is -2c.
For $$0 < r < \sqrt{\frac{2GM}{c^2}}$$ there is no outbound radial coordinate speed, just two different inbound coordinate speeds, which makes sense if you think of black holes as places light can't escape from.

In the 1916 Schwarzschild metric, $$d\tau^{2} = \left(1-\frac{2GM}{c^2r} \right) c^2\, dt^2 -\frac{dr^2}{ \left(1-\frac{2GM}{c^2r} \right)}- r^2 \, d\theta^2-r^2\sin^2\theta \, d\phi^2$$ we only have to solve $$ \left(1-\frac{2GM}{c^2r} \right) c^2 = \frac{v^2}{ \left(1-\frac{2GM}{c^2r} \right)}$$ to get $$v = \pm \left(1-\frac{2GM}{c^2r} \right) c$$ in the radial direction. Thus the inbound and outbound speeds of light always have the same coordinate speed and thus when $$r = \sqrt{\frac{2GM}{c^2}}$$, both are equal to zero, therefore the criterion Farsight used to disparage the Gullstrand-Painlevé metric applies doubly to his chosen metric, thus must be rejected as an inconsistent special pleading.

If Farsight wishes to object that the Gullstrand-Painlevé metric exhibits different coordinate speeds of light in different directions, then may I preemptively point out the same holds for the 1916 Schwarzschild metric. Assuming $$dr=0, \, d\phi = 0, \, d\theta =\frac{v}{r} dt, d\tau^{2} = 0$$ we get the speed of light perpendicular to the radial direction from:
$$\left(1-\frac{2GM}{c^2r} \right) c^2 = v^2$$ or $$v = \pm \sqrt{1-\frac{2GM}{c^2r}} c$$ which makes the 1916 solution anisotropic with respect to the coordinate speed of light.

Neither anisotropy in perpendicular or opposite directions is a reason to reject a proposed set of space-time coordinates. Any reasoning to reject must come from the geometry and comparison to Einstein's curvature equation at the heart of GR.

Indeed, the reason the Schwarzschild metric must have a singularity at the event horizon is that it is incapable of saying that infinitesimal motion inward isn't similar to the same motion outward therefore it blows up at the horizon to avoid the question of trapping light and objects.

 

[Schmelzer]

The river/waterfall model is mathematically validated and has been accepted by arxiv

Arxiv does not make any peer-review, it may reject some stuff out of prejudice, but that's all, an "acceptance" means nothing. Then, learn to read, I have not questioned at all the mathematics of the paper. And learn to read the arxiv site, it mentions publications of the articles in journals. The paper has been accepted and published by AJP. Which is a journal for popular articles, with teachers and their pupil as the auditory, thus, not really scientific, but nonetheless some peer-review (contrary to arxiv itself).

Actually interesting that you decide to hop onto the crank bandwagon, considering that you claim your own "ether"paper by the same publisher predicts more than mainstream interpretation of GR.
I smell some hypocrisy.

First, arxiv ist not a "publisher", but an eprint server. Then, I do not care about any bandwagons, but criticize an article.

Well then do it appropriatley and submit a paper pointing out what you believe are errors.
At least it has had a number of citations as distinct from your own ether paper.

I have written a more detailed critique, and have even a response of A. Hamilton. Which contains, in particular, the following: "The paper is quite critical of our paper Hamilton & Lisle published in AJP in 2008. I accept those criticisms;" See http://ilja-schmelzer.de/papers/river.php for my article as well as the full response.

As I have already explained, I do not expect citations for ether papers during the next years. We have to wait until string theory has been really given up, and people really start to search for alternatives, without prejudices.

 

[paddoboy]

Arxiv does not make any peer-review, it may reject some stuff out of prejudice, but that's all, an "acceptance" means nothing.

Please, enough with the dramatic conspiracies!

Then, learn to read, I have not questioned at all the mathematics of the paper.

That's nice and is what I said about being validated.

First, arxiv ist not a "publisher", but an eprint server. Then, I do not care about any bandwagons, but criticize an article.

Criticise all you like, obviously as I have shown, you do have somewhat of an agenda and are consequently biased in your opinion.

I have written a more detailed critique, and have even a response of A. Hamilton. Which contains, in particular, the following: "The paper is quite critical of our paper Hamilton & Lisle published in AJP in 2008. I accept those criticisms;" See http://ilja-schmelzer.de/papers/river.php for my article as well as the full response.

I'm not concerned about any critique of your paper, I'm speaking of Professor Hamilton's mathematically validated river/water fall model that has been cited.

As I have already explained, I do not expect citations for ether papers during the next years. We have to wait until string theory has been really given up, and people really start to search for alternatives, without prejudices.

So you have no prejudices against string theory?
Science/cosmology are always searching for alternatives where required, and improvements/modifications of existing models. That will almost certainly be from mainstream.

 

[Schmelzer]

There are two interpretations, which Kevin Brown mentions in The Formation and Growth of Black Holes. After reading Einstein talking about the speed of light varying with position, I conclude that the "other" interpretation is the correct one.

I prefer my own ether interpretation too, but it would be stupid to criticize the others for inconsistency if they are, however stupid, consistent.

However the coordinate speed of light at the event horizon is zero, and it can't go any lower than that. So there's no gradient in the coordinate speed of light. And so no force of gravity.

It is zero in one direction, in the other direction quite large. At least in coordinates which are non-degenerated. Of course, degenerated coordinates are irrelevant.

I think the issue is with "all coordinate systems are valid". IMHO people take this too far, and invent fantasy coordinate systems that just don't match Einstein's description of what a gravitational field is.

Not all of them are valid, they may degenerate, and degenerated coordinates are not valid. Otherwise, all coordinates are equivalent mathematically, because one has formulas to connect them.

The description given by Einstein does not require much. There should be a symmetric tensor field in the four-dimensional spacetime, with signature (1,3), that means three spatial directions and one time-like one.

 

[Schmelzer]

Please, enough with the dramatic conspiracies!

What conspiracy? Arxiv.org is not peer-reviewed, this is simply an information about a well-known fact. It has never been claimed to be peer-reviewed.

I'm not concerned about any critique of your paper, I'm speaking of Professor Hamilton's mathematically validated river/water fall model that has been cited.

So I have, in the article, criticized Hamilton's paper. And Hamilton has written a review of my critique, and accepted the main points. My paper, as well as his reply, is, of course, also about some other things, namely about the Lorentz ether interpretation of the Einstein equations of GR, which I have suggested as an improvement of his river model.

So you have no prejudices against string theory?

Of course I have. String theory is not even wrong. With this characterization of string theory, I simply follow some other scientists, who have written books about this.

But, given that I simply follow others here, without studying string theory myself, this is even quite correctly characterized as "prejudice", and in this sense similar to all your opinions about whatever theories discussed here.

 

[paddoboy]

What conspiracy? Arxiv.org is not peer-reviewed, this is simply an information about a well-known fact. It has never been claimed to be peer-reviewed.

I'm not referring to that.
Are you now being intellectually dishonest?

it may reject some stuff out of prejudice,

So I have, in the article, criticized Hamilton's paper.

That's nice, yet it still stands as a mathematically validated often cited paper.

Of course I have. String theory is not even wrong. With this characterization of string theory, I simply follow some other scientists, who have written books about this.

I have never said that string theory is fully accepted by mainstream...It is still debatable and will be until we are able to observe at those scales.

But, given that I simply follow others here, without studying string theory myself, this is even quite correctly characterized as "prejudice", and in this sense similar to all your opinions about whatever theories discussed here.

I'm not prejudiced like yourself...I do not have an agenda like yourself, and I have no ego to bruise. In my capacity I accept what works and is theorised, and consider reasonably logical speculative scenarios such as the Superforce.
That capacity to understand properly may certainly be lower than yours, but by the same token, I am not in anyway inhibited by an agenda, which is obvious in your case, judged on what you post.

 

[OnlyMe]

All cosmologists are doing is modelling the gravitational field according to observations. If the model makes successful predictions and is not falsified, then you writing it off as hypothetical is rather silly.

Anytime the model includes an event horizon or anything inside of an event horizon it is no longer modeling anything that has been observed. It is extending what limited information we have based on observation and theory to conclusion beyond observation.

You dont believe the gravity field we all exist in is real?

That does not makes sense. GR was developed to explain gravitation that included the earth, sun and other planets.., and it does that very well. Solutions that predict singularities and infinities die a death of their own creation and it does not have anything to do with gravity in a weak field. It is not even certain that they (any solution to EFE), can be trusted to acuartely predict what a gravitational field would be like at or inside of an event horizon, because once that point is reached the singularity and infinities are unavoidable, within the context of those solutions...

When you misinterpret what Professor Hamilton has said, maybe you should also consider that the "No Hair theorem" is overwhelmingly accepted by mainstream cosmology. The "No Hair Theorem" of course is that a BH can have only three properties....that being mass, spin and charge, and both the latter two are negated over time.

That was a very limited simplified restatement of a quote from the link. I left the links (not active) to the Waterfall analogy and what is Realistic, on purpose. The later further supports the understanding that the charged black hole, is a theoretically based hypothetical that does not exist... It is not realistic.

BTW it could be argued that the No Hair Theorem is a theorem in name only and based on speculation and belief. Remember no one has seen a black hole after all.

You do understand that a large part of cosmology today is inherently speculative. It is based on many many unconfirmed assumptions and an extension of weak field observations about gravitation, to extremes of both distance and.., the singularities few if any believe actually exist.

If the singularity does not exist you cannot with any certainty, know were a solution to EFE that predicts a singularity, begins to fail, as in begins to describe a gravitational field that cannot exist in our reality. All we can say is that it does a good job of describing what we can observe which stops well outside of any event horizon. Observations that support the existence of black holes is limited to not being able to see things that seem to be the center of strong gravitational fields. Nothing in what we can observe tells us exactly what we cannot see... That is the domain of theory and speculation and will remain so for a very long time.

None of the above should be interpreted to mean that I don't believe black holes exist. I just don't believe there are any singularities.

We cannot know that what we believe are black holes today, are not just massive compact objects that no longer have any atomic structure. I did not say no subatomic structure! Most of the EM radiation we are able to detect and measure is dependent on atoms. Essentially no atoms no light. With or without an event horizon. The gravitational field outside of the Schwarzchild radius, would be indistinguishable!

And I am not saying that is what is. I only offered that as an example to demonstrate that when we talk about black holes, as soon as we reach an event horizon, we are speculating. And it does not matter whether you are Einstein, Steven Hawking or their next door neighbor, it is still speculation.

After all of this, if the discussion is about a particular solution, it's predictions, even how it compares to another.., or how it compares to what can be observed, fine just stay aware that just because a solution is mathematically valid, does not make it a accurate description of reality.

 

[paddoboy]

Anytime the model includes an event horizon or anything inside of an event horizon it is no longer modeling anything that has been observed. It is extending what limited information we have based on observation and theory to conclusion beyond observation.

Yes, by learned men educated in the discipline of cosmology, and quite reasonable and ethical to do. Certainly not some BNS nonsense by some "would be if he could be" nor any of your usual hackneyed repetitive stuff you go on with like a stuck record. Stop avoiding the point OnlyMe.

That does not makes sense. GR was developed to explain gravitation that included the earth, sun and other planets.., and it does that very well. Solutions that predict singularities and infinities die a death of their own creation and it does not have anything to do with gravity in a weak field.

It makes perfect sense for the reasons already stated along with the general scientific methodology.
GR in predicting its own downfall, allows cosmologists to "theorise speculate reasonably" right up to the limitations of itself.

It is not even certain that they (any solution to EFE), can be trusted to acuartely predict what a gravitational field would be like at or inside of an event horizon, because once that point is reached the singularity and infinities are unavoidable, within the context of those solutions...

We can reasonably predict inside the EH, at least up to the singularity.

That was a very limited simplified restatement of a quote from the link. I left the links (not active) to the Waterfall analogy and what is Realistic, on purpose. The later further supports the understanding that the charged black hole, is a theoretically based hypothetical that does not exist... It is not realistic.

So the no hair theorem does not exist now? 80 years of cosmology and theoretical cosmology by the likes of John Wheeler can be confined to the dustbin now?
Really, in your little game to be hard on me, you are actually sounding more like the god every day.
Do better.

BTW it could be argued that the No Hair Theorem is a theorem in name only and based on speculation and belief. Remember no one has seen a black hole after all.

More usual nonsense. Perhaps you need to study the scientific method and what is reasonably accepted on indirect evidence.
This continued fence sitting is not going to do your anatomy any good.
And if you believe an argument can be fabricated to invalidate the no hair theorem, then go ahead. Should prove interesting.

You do understand that a large part of cosmology today is inherently speculative. It is based on many many unconfirmed assumptions and an extension of weak field observations about gravitation, to extremes of both distance and.., the singularities few if any believe actually exist.

I can only conclude OnlyMe that you are being totally intellectually dishonest, that which you have often accused the god of.
Yes a large part of cosmology is speculative, speculation by learned men educated in the field that are able to come up with reasonable assumptions, which now you want to dismiss in your evangelistic like mission.
And again no one has said anything about any physical real singularity, but up to it, cosmologists are able to logically speculate, as other professors have informed you. Tough titty if that ruffles your doubting thomas feathers somewhat. That's the way it is and they are doing OK.

If the singularity does not exist you cannot with any certainty, know were a solution to EFE that predicts a singularity, begins to fail, as in begins to describe a gravitational field that cannot exist in our reality. All we can say is that it does a good job of describing what we can observe which stops well outside of any event horizon. Observations that support the existence of black holes is limited to not being able to see things that seem to be the center of strong gravitational fields. Nothing in what we can observe tells us exactly what we cannot see... That is the domain of theory and speculation and will remain so for a very long time.

Rubbish! And the reality of the situation and the reputable replies we have had on various issues support what I am saying and discredit your cynical unreal approach.

None of the above should be interpreted to mean that I don't believe black holes exist. I just don't believe there are any singularities.

2 bob each way again?
I'll tell you something OnlyMe, I was surprised somewhat the other day when I smelt a rather religious overtones in a post from the god. Seriously, you are sounding the same.
I mean how often do we hear their old catch cry "Ahaa, but it's only a theory!"
No, we don't observe BH's directly, but we do have convincing evidence of their existence...We don't see DM either, but are nearly just as confident they exist due to indirect evidence.....DE also....and who can forget the BB? We never see that either but the indirect evidence is so overwhelming that even the Catholic church now accept it.
Now don't get me wrong OnlyMe.....I have nothing at all against religious folk as long as they stick to their religion and dont try and deride the sciences.

We cannot know that what we believe are black holes today, are not just massive compact objects that no longer have any atomic structure. I did not say no subatomic structure! Most of the EM radiation we are able to detect and measure is dependent on atoms. Essentially no atoms no light. With or without an event horizon. The gravitational field outside of the Schwarzchild radius, would be indistinguishable!

And I am not saying that is what is. I only offered that as an example to demonstrate that when we talk about black holes, as soon as we reach an event horizon, we are speculating. And it does not matter whether you are Einstein, Steven Hawking or their next door neighbor, it is still speculation.

There we have a dog's breakfast of intellectual dishonesty, cynical raving, and teaching granny how to suck eggs.

After all of this, if the discussion is about a particular solution, it's predictions, even how it compares to another.., or how it compares to what can be observed, fine just stay aware that just because a solution is mathematically valid, does not make it a accurate description of reality.

Your efforts in trying to project a sense of fairness and fence sitting has reached the stage of crankdom OnlyMe....sorry about that.

 

[OnlyMe]

Following is a quote of the full text of my post the one you just responded to. I don't think you find anywhere that I even mentioned you. I spoke only to the issues.

Anytime the model includes an event horizon or anything inside of an event horizon it is no longer modeling anything that has been observed. It is extending what limited information we have based on observation and theory to conclusion beyond observation.



That does not makes sense. GR was developed to explain gravitation that included the earth, sun and other planets.., and it does that very well. Solutions that predict singularities and infinities die a death of their own creation and it does not have anything to do with gravity in a weak field. It is not even certain that they (any solution to EFE), can be trusted to acuartely predict what a gravitational field would be like at or inside of an event horizon, because once that point is reached the singularity and infinities are unavoidable, within the context of those solutions...



That was a very limited simplified restatement of a quote from the link. I left the links (not active) to the Waterfall analogy and what is Realistic, on purpose. The later further supports the understanding that the charged black hole, is a theoretically based hypothetical that does not exist... It is not realistic.

BTW it could be argued that the No Hair Theorem is a theorem in name only and based on speculation and belief. Remember no one has seen a black hole after all.

You do understand that a large part of cosmology today is inherently speculative. It is based on many many unconfirmed assumptions and an extension of weak field observations about gravitation, to extremes of both distance and.., the singularities few if any believe actually exist.

If the singularity does not exist you cannot with any certainty, know were a solution to EFE that predicts a singularity, begins to fail, as in begins to describe a gravitational field that cannot exist in our reality. All we can say is that it does a good job of describing what we can observe which stops well outside of any event horizon. Observations that support the existence of black holes is limited to not being able to see things that seem to be the center of strong gravitational fields. Nothing in what we can observe tells us exactly what we cannot see... That is the domain of theory and speculation and will remain so for a very long time.

None of the above should be interpreted to mean that I don't believe black holes exist. I just don't believe there are any singularities.

We cannot know that what we believe are black holes today, are not just massive compact objects that no longer have any atomic structure. I did not say no subatomic structure! Most of the EM radiation we are able to detect and measure is dependent on atoms. Essentially no atoms no light. With or without an event horizon. The gravitational field outside of the Schwarzchild radius, would be indistinguishable!

And I am not saying that is what is. I only offered that as an example to demonstrate that when we talk about black holes, as soon as we reach an event horizon, we are speculating. And it does not matter whether you are Einstein, Steven Hawking or their next door neighbor, it is still speculation.

After all of this, if the discussion is about a particular solution, it's predictions, even how it compares to another.., or how it compares to what can be observed, fine just stay aware that just because a solution is mathematically valid, does not make it a accurate description of reality.

And here is an redacted quote of your post responding to the above... Or rather that portion that was directed personally at me rather than the subject.

nor any of your usual hackneyed repetitive stuff you go on with like a stuck record. Stop avoiding the point OnlyMe.

Really, in your little game to be hard on me, you are actually sounding more like the god every day.
Do better.


More usual nonsense. Perhaps you need to study the scientific method and what is reasonably accepted on indirect evidence.
This continued fence sitting is not going to do your anatomy any good.

I can only conclude OnlyMe that you are being totally intellectually dishonest, that which you have often accused the god of.
which now you want to dismiss in your evangelistic like mission.
Tough titty if that ruffles your doubting thomas feathers somewhat.

and discredit your cynical unreal approach.

2 bob each way again?
I'll tell you something OnlyMe, I was surprised somewhat the other day when I smelt a rather religious overtones in a post from the god. Seriously, you are sounding the same.

There we have a dog's breakfast of intellectual dishonesty, cynical raving, and teaching granny how to suck eggs.

Your efforts in trying to project a sense of fairness and fence sitting has reached the stage of crankdom OnlyMe....sorry about that.

Do you think that you can ever have a civil discussion with anyone who does not see things exactly as you do... Even when you are discussing an area of theoretical physics that not all of the authorities agree on?

Please go back read your post the one I initially responded to and then my response again. Your responses did not always make sense. Keep in mind there are many solutions to EFE and some of them are mutually exclusive... None of those solutions are the heart of GR, the weak field limit of EFE that can and has been confirmed is. The failure of any or all solutions are not the downfall of GR.

 

[The God]

and so... what?

Pretty much any metric you care to name. At large distances from a mass, spacetime is always approximately flat.

I like to call it the universe.

Generally this is the signature style of Paddoboy. Arguing (and abusing too) without proper understanding of the point in hand.

.......We emphasize that the background being flat does not
mean that the metric is spatially flat.......

..........The statement that the background spacetime in the
river model is flat is not a statement about the metric
gµν being flat. Rulers and clocks swimming in the river of
space measure not distances and times in the background
space.........

It is ridiculous to suggest that some background Universe (which is a flat space time metric ) is observing the 'river metric' in foreground. You missed the whole point of the paper.....Model for lay persons.

 

[paddoboy]

And here is an redacted quote of your post responding to the above... Or rather that portion that was directed personally at me rather than the subject.

:shrug: Really OnlyMe, whatever!
All your posts directed at me are ever saying is we don't know with 100% certainty. Then you get all indignant when I call you out and accuse you of intellectual dishonesty?
I mean how many times to I have to say that I know what is and is not 100% certain? Yet you keep on with that line.
Now go back and read your own posts, and instead of telling me "we don't know for sure" start recognising how logical and reasonable some of these assumptions are. Forget your mission! It has no effect on me!

 

[paddoboy]

It is ridiculous to suggest that some background Universe (which is a flat space time metric ) is observing the 'river metric' in foreground. You missed the whole point of the paper.

That's coming from a lay person who can't even recognise the fact that GR predicts total collapse once the Schwarzchild radius is breached, or that BH's do really exist in the first place.
Please support what you say, otherwise you are pissing in the wind.
And with regards to abuse, I would look at yourself first my friend.

 

[The God]

In high school Physics, river flow numericals are taken up. Say the stream is moving at a speed Vr in some direction and a swimmer is attempting to swim at a speed Vb in some direction, then finding out travel time, resultant velocity etc etc is taught and taken up.

Probably this is what prompted Hamilton to give an analogical model about BH dynamics inside EH as he though people with less mathematical rigour can understand this. Thus the river model. It is no metric and it has no value added contribution to scientific pursuit, and neither Prof Hamilton claims so.

Analogy is simple and straightforward for non spinning neutral BH. The Schwarzschild Metric in Schwarzchild coordinates give problem even at EH (division by zero), but this problem can be eliminated if we consider Gullstrand-Painlev coordinates. Thats the starting point for Prof Hamilton. He very simply says that river starts flowing from an origin point of a very high mountain (r = infinity and Vr = 0) and acquires speed Vr = c at EH and this keeps increasing and approaches infinity (?) at r = 0. Any object irrespective of his speed Vb (as constrained by SR) gets dragged by this river flow too (simple High School Maths to calculate travel time etc). To make life simpler he attempts to say that assume that this river (space flow) flows against a backdrop of flat spacetime. Inward journey is complete.

In the outward direction since at the EH, the stream speed is c and inside it is faster than c, suggesting that nothing not even light can be seen from outside once it has crossed irrespective of direction of Vb. He further says that by chance if the object speed Vb is c at EH, then it appears to be standstill with resultant speed being zero for an outside observer.

The problem with this model is

a. River Flow is Energy.
b. Anything at r = non infinity will have a drag towards the centre of BH...ultimately collapsing inside.

But no one bothers about these apparent problems, because it is of no value to science, it is just a model like that raisin expansion model.

 

[brucep]

Farsight,


Einstein isn't the be-all and end-all of relativity. There's been almost 100 years of work on general relativity since Einstein. Why are you still stuck in 1916?


What utter rot.

"Gullstrand–Painlevé coordinates are a particular set of coordinates for the Schwarzschild metric – a solution to the Einstein field equations which describes a black hole."
Link: https://en.wikipedia.org/wiki/Gullstrand–Painlevé_coordinates


You skipped over the maths of the article and just read the last paragraph, obviously.

Just because Einstein was baffled back in 1922 doesn't mean the solution isn't a perfectly valid description of the Schwrarzschild geometry.


Nonsense.

He's still claiming the remote bookkeeper coordinates is preferred over local proper coordinatess?We've been over this with Farsight and RJ Berry. Several times. He's pulling your chain. This nonsense leads to both them claiming black holes don't form in a finite time. And for Farsght he uses that nonsense to say the local speed of light varies in the local gravitational field. He actually claims that's what Einstein had in mind.

 

[The God]

That's coming from a lay person who can't even recognise the fact that GR predicts total collapse once the Schwarzchild radius is breached, or that BH's do really exist in the first place.
Please support what you say, otherwise you are pissing in the wind.
And with regards to abuse, I would look at yourself first my friend.

Your problem is Paddoboy, most of the time you do not even understand what is Mainstream, and you argue and abuse to defend the incorrect notion you have about science.