Also, any photon produced inside an event horizon (at whatever distance) can only propagate towards the centre; it can never propagate outwards.
Ah, okay, then it depends on the density distribution of the energy inside the event horizon. If, for example, you have a collapsing shell, then obviously due to Birkhoff's theorem it will be able to do so. But if the inner regions of said distribution are also inside their own event horizon, then (probably) it won't be possible. At the very least, the photon can never escape that event horizon.
Here we can clearly see one important thing: if density is constant, and there is an event horizon outside the object (or on its outer surface), this condition will not hold for small radii, but it will at some point kick in. A photon produced at r = 0 may be able to travel a little distance, but at some point it will reach a radius where the enclosed mass will be large enough to create an event horizon, and then the photon will not be able to travel to larger radii.
Now the moot question is under known Physics, by applying the known concepts, can we make a plausible case that the entire structure comes out of its event horizon? There appears a possibility, as we could show that a photon could travel away from the center, which was hitherto ignored aspect.
That is precisely what the alternative section is for.(I have attempted by resorting to my proposed PSMR hypothesis, but as per James that I may take up in alternative section, on this thread only under known Physics. PSMR = Progenitor State of Matter & Radiation.)
Incorrect. Under a specific uniform density distribution this is true, but not in general. For example: I can have a small metal ball-bearing (which has a uniform density distribution) sitting on my desk without it forming any event horizon either at its surface or outside of it. Likewise, with a high enough uniform density, the event horizon will be outside the object.True, but under uniform density distribution, as I stated earlier, when an object is just at EH, even the inner 99.99% shell will be out of its EH, only the outer most surface shall be inside EH. .
(I'm interpreting the "will fall under EH" as "satisfies the event horizon condition".) True.Technically as the object keeps collapsing more and more fraction will fall under EH.
(I'm not seeing any images in those posts?)This point is explained with some simple figures in #61 and then in #66.
No worldline exists that can cross the event horizon. The only option is evaporating the mass away through Hawking radiation. I'm not familiar enough with it to answer this question, but it seems like something that probably has already been handled in some literature.Yes, you have grasped it correctly. The photon produced at r = 0, may travel outward till a point where due to collapsing core it encounters the now inner shell beneath its event horizon. So technically it can never come out of original EH, but it can surely run away from center when first emitted at r = 0.
This photon description is not there in any literature available, probably due to the fact that under prevalent GR the ultimate fate of this photon is singularity only.
Now the moot question is under known Physics, by applying the known concepts, can we make a plausible case that the entire structure comes out of its event horizon? There appears a possibility, as we could show that a photon could travel away from the center, which was hitherto ignored aspect.
With all due respect, if that hypothesis is bereft of as many essential GR and/or QCD calculations as your previous one, it's not a hypothesis but merely baseless speculation. Might I suggest you strengthen that one first, before diving even deeper into material you clearly are not familiar with?(I have attempted by resorting to my proposed PSMR hypothesis, but as per James that I may take up in alternative section, on this thread only under known Physics. PSMR = Progenitor State of Matter & Radiation.)
RajeshTrivedi said:...but under uniform density distribution, as I stated earlier, when an object is just at EH, even the inner 99.99% shell will be out of its EH, only the outer most surface shall be inside EH. . Technically as the object keeps collapsing more and more fraction will fall under EH.
Incorrect. Under a specific uniform density distribution this is true, but not in general. For example: I can have a small metal ball-bearing (which has a uniform density distribution) sitting on my desk without it forming any event horizon either at its surface or outside of it. Likewise, with a high enough uniform density, the event horizon will be outside the object.
My formula clearly states that only one specific uniform density distribution will have the event horizon on its outer surface.
Ah, I see, I misunderstood your "an object is just at EH". We are indeed in full agreement on this.No, its not incorrect. The point is when an object (of any mass M) is at its Event Horizon, then under uniform density assumption all other inner fractional mass shells will be out of their respective event horizon. Simple algebra will yield that when an object of mass M is of size Rs (Schwarzschild Radius), then an inner fractional mass xM (0<x<1) will be out of xM event horizon as the event horizon of xM is at xRs, but the radius of xM mass will be (x)^(1/3)Rs, and (x)^(1/3) > x.
Your formula is correct but you missed the cross referencing of M with Rs.
Ah, I see, I misunderstood your "an object is just at EH". We are indeed in full agreement on this.
Now let us move over to the collapsing "object just at its EH", the escape velocity is c; let a photon be fired from its surface (r=Rs), why can it not travel away from this surface ? (may be like that bullet fired from the earth surface at 1 km/sec).
For an object with a constant density distribution, which a neutron star has not.Ok, so we agree that when the object is of its event horizon size, then photon released at any interior point can travel towards outer surface (for whatever duration).
Yes.As the collapse continues (well within outer EH), more and more fraction of this object gets inside "that fraction's" event horizon, till it becomes a singularity and no more outward direction of motion. So I am now working on this finite time from first fall beneath EH till singularity is formed, to see if singularity can be avoided by invoking the accepted Physics.
This is one of the reasons escape velocity is a poor analog. Look at the Kruskal diagram: there is no worldline possible where the photon moves away from the surface. Spacetime is warped to such a degree, that all lightlike worldliness from r = 1 cannot exceed r = 1. The calculations tell us this is the case. If your intuition tells you differently, it's because this is a GR environment, and your intuition doesn't work properly there. (Don't worry; this is normal. There are very few people (if any at all) that have an intuitive understanding of GR (or QCD)).but before that, I have one more equally important point, and could not get the clarification.
Even though escape velocity is irrelevant in GR, but still its a physical parameter quite relevant around a celestial object. So a reference can be made. On the surface of the earth, the escape velocity is around 11.2 km/sec, it means that an object fired at 11.2 km/sec on the surface will leave the gravity of earth, but it does not mean that an object fired at lesser velocity (say 1 km/sec) will not attain any height, it will certainly move away from the earth and will fall back. Now let us move over to the collapsing "object just at its EH", the escape velocity is c; let a photon be fired from its surface (r=Rs), why can it not travel away from this surface ? (may be like that bullet fired from the earth surface at 1 km/sec).
If a singularity can be eliminated by a coordinate transformation, it was never a (physical) singularity.Even if we try this question in GR, then there is nothing untoward about just formed EH, moreover the curvature of spacetime can be made small by considering a very large mass object at EH, furthermore the possible singularity (on account of r = 2M) in case of Schwarzschild metric can be eliminated by changing to different coordinates.
No, this is you using your intuition, instead of GR. A bullet fired at r = 2M (the event horizon) must travel inward, towards r = 0, and faster than a photon. Look at the Kruskal diagram: that's what must happen (according to GR).So a bullet fired at r = 2M) outwardly just when the object is also of this size) should be able to move at least a little distance away from surface.
For an object with a constant density distribution, which a neutron star has not.
Yes.
This is one of the reasons escape velocity is a poor analog. Look at the Kruskal diagram: there is no worldline possible where the photon moves away from the surface. Spacetime is warped to such a degree, that all lightlike worldliness from r = 1 cannot exceed r = 1. The calculations tell us this is the case. If your intuition tells you differently, it's because this is a GR environment, and your intuition doesn't work properly there. (Don't worry; this is normal. There are very few people (if any at all) that have an intuitive understanding of GR (or QCD)).
If a singularity can be eliminated by a coordinate transformation, it was never a (physical) singularity.
No, this is you using your intuition, instead of GR. A bullet fired at r = 2M (the event horizon) must travel inward, towards r = 0, and faster than a photon. Look at the Kruskal diagram: that's what must happen (according to GR).
And no, working from Schwarzschild coordinates is no good, because then a bullet cannot be fired: time is frozen at the event horizon when viewed from an observer infinitely far away. (That actually also means it will never travel outward, because it doesn't travel at all!)
Any photon emitted outwards from the EH, will arc back and fall into the BH, unless it is directed exactly radially away...In that case ignoring everything else and in the FoR of a photon [which is impossible anyway] the photon will hover there never getting away but able to resist falling in.
"Hovering"may be the wrong word.....See the River analogy...You have rightly understood it, the photon has no rest frame, and 'hovering' suggest rest frame for photon, so this is just one of those inaccurate analogies.
Gee, I must be having an illusion. And of course the futility of it is that you over many years, have submitted papers, made many claims here and elsewhere, to basically invalidate GR and like the many other anti GR proponents that have graced us with their presence, you like them have failed.It is not my case to argue here (because of shear futility),
Well it certainly at this time remains unevidenced, and unobserved, just as worm holes do, but hey, since we cannot be sure of what is at the Singularity region, all options remain open I suggest. Funny, I have yet to see you comment on the validation of gravitational waves another prediction of GR, and/or the Lense Thirring effect for that matter.Kruskal which leads you to absurd white hole
I fully agree. From this point onwards, only proper GR calculation.Let us leave intuition aside.
Not mere error bars, simply the wrong answer. Newtonian mechanics breaks down in strong gravity; see the precession of Mercury. That's not just "higher error bars", because they are actually very small. It's the wrong value.It is not my case to argue here (because of shear futility), that you consider Kruskal which leads you to absurd white hole, over the Newtonian which may give you results with somewhat higher error bars.
No, in the presence of strong gravity Newtonian mechanics give wrong answers. GR is the model to use.you cannot say that Newtonian just not applicable there, after all the motion of objects around a Black hole is being determined by Newtonian only.
Please stop using Newtonian concepts in a GR environment. "Escape velocity" is the wrong way to think about this, as it is not a fundamental concept in GR. Worldlines are.Anyways, you fail to consider the salient point, a celestial object irrespective of its gravity (mind you an object just at its EH, has a finite gravitational potential energy for a test particle at EH) will have an escape velocity.
False, as argued earlier.Escape velocity is a universal parameter which conceptually supersedes the underlying theory,
False, as argued earlier.you cannot say that since we are discussing GR so escape velocity is not applicable or meaningless. It is there.
But seeing as you disagree: calculate for me the escape velocity under the Schwarzschild metric, and then show how it is a well-defined concept in GR. No more intuition, remember? Demonstrate that your claim that escape velocity is applicable and meaningful is true. Proof me wrong.
I'll ask you again: please demonstrate that escape velocity is primary in GR. Merely repeating your assertion is dodging the question.You are not appreciating that the concept of escape velocity is primary (about the motion of a test particle around any celestial object).
No, and I never claimed as such. The gravity on earth's surface is weak enough that Newtonian gravity is a good enough approximation. This is not the case near an event horizon.So any theory of of gravity must consider and must explain the escape velocity aspect. Say even on earth surface GR equations, with initial velocity of test particle at 11.2 km/sec, must lead to a motion trajectory (whatever you name it) which will make this particle unbound. You cannot say >11.2 km/sec in GR will not make this particle unbound. Can you?
If the bullet is fired from the event horizon, it cannot travel outwards (as seen from an observer infinitely far away); see Schwarzschild. If the bullet is fired outside of the event horizon (and has a high enough speed) away from the event horizon, it will be able to travel to infinity. If the bullet is fired from within the event horizon, it will travel towards the center.Now, as i said a stone thrown at 1 km/sec (or whatever speed less than escape velocity) will travel upward but will not become unbound, it will come back and strike the earth. so when the object is just at EH, not yet collapsed to singularity, it is still in definable space (not spacetime), then if a bullet is fired from the surface of this object, it will move upward; why?
I strongly suspect you are once again using Newtonian concepts while they are not valid (we are in a GR environment), as KE is not a fundamental concept in GR, and neither is gravitational potential energy. Please start using the proper descriptive model.simply because this bullet has a finite gravitational potential energy, and a KE is added to it.
And it is wrong, because you are using Newtonian gravity in a domain where it is not valid.No intuition, it is simple conservation law.
I'll ask you again: please demonstrate that escape velocity is primary in GR. Merely repeating your assertion is dodging the question.
No, and I never claimed as such. The gravity on earth's surface is weak enough that Newtonian gravity is a good enough approximation. This is not the case near an event horizon.
If the bullet is fired from the event horizon, it cannot travel outwards (as seen from an observer infinitely far away); see Schwarzschild. If the bullet is fired outside of the event horizon (and has a high enough speed) away from the event horizon, it will be able to travel to infinity. If the bullet is fired from within the event horizon, it will travel towards the center.
I strongly suspect you are once again using Newtonian concepts while they are not valid (we are in a GR environment), as KE is not a fundamental concept in GR, and neither is gravitational potential energy. Please start using the proper descriptive model.
And it is wrong, because you are using Newtonian gravity in a domain where it is not valid.
Please stop using Newtonian gravity in GR environments.
That's fully up to you.This wont lead us anywhere.
But you are, because you keep using non-GR concepts, like escape velocity, in an environment where GR needs to be used.I am not interested in arguing against GR,
And I am pointing out some of the issues in it.I am proposing what I consider appropriate.
Of a forum called "sci forums".Of course in alternative section.
That's fully up to you.
But you are, because you keep using non-GR concepts, like escape velocity, in an environment where GR needs to be used.
And I am pointing out some of the issues in it.
Of a forum called "sci forums".