Black holes and the relativity of simultaneity

[RJBeery]

Except that the gravity generated by that mass is greater than that required to overcome neutron repulsion. Our physics says it cannot be a neutron star. It does collapse to something smaller, we just don't know what. Whatever that is, we call it a black hole.

"Does" is the present indicative form of the verb "do". You are assigning time dependent words to your description without defining time dependency. My argument is simple: if "existence" has any meaning whatsoever it must be defined. I claim A "exists concurrently" with B if they are space-like separated. This has the benefit of being unambiguous and absolute for all frames of reference, so this is not a case of coordinate or frame dependency.

Do you take issue with this definition? How would you improve on it?

 

[Schmelzer]

I claim A "exists concurrently" with B if they are space-like separated. This has the benefit of being unambiguous and absolute for all frames of reference, so this is not a case of coordinate or frame dependency. Do you take issue with this definition? How would you improve on it?

If A and B are spacelike separated, they "exist concurrently". If B and C are spacelike separated, they also "exist concurrently". If A and B "exist concurrently", and B and C "exist concurrently", I would expect that also A and C "exist concurrently". But A and C may not be spacelike separated, A may be the past of C. One solution may be fatalism - the whole spacetime, past as well as future, "exist concurrently". The other one a preferred frame.

 

[Schmelzer]

http://arxiv.org/abs/1503.03873
The 6 billion solar mass supermassive black hole at the center of the giant elliptical galaxy M87 powers a relativistic jet. Observations at millimeter wavelengths with the Event Horizon Telescope have localized the emission from the base of this jet to angular scales comparable to the putative black hole horizon. The jet might be powered directly by an accretion disk or by electromagnetic extraction of the rotational energy of the black hole. However, even the latter mechanism requires a confining thick accretion disk to maintain the required magnetic flux near the black hole. Therefore, regardless of the jet mechanism, the observed jet power in M87 implies a certain minimum mass accretion rate. If the central compact object in M87 were not a black hole but had a surface, this accretion would result in considerable thermal near-infrared and optical emission from the surface. Current flux limits on the nucleus of M87 strongly constrain any such surface emission. This rules out the presence of a surface and thereby provides indirect evidence for an event horizon.

Thanks. Broderick and Narayan I have already considered in http://arxiv.org/abs/1003.1446 and found that the weak point is their steady state assumption. Here, they make it again: "Thus, assuming that the system has reached steady state ...".

 

[RJBeery]

If A and B are spacelike separated, they "exist concurrently". If B and C are spacelike separated, they also "exist concurrently". If A and B "exist concurrently", and B and C "exist concurrently", I would expect that also A and C "exist concurrently". But A and C may not be spacelike separated, A may be the past of C. One solution may be fatalism - the whole spacetime, past as well as future, "exist concurrently". The other one a preferred frame.

Let me consider this.

 

[RJBeery]

If A and B are spacelike separated, they "exist concurrently". If B and C are spacelike separated, they also "exist concurrently". If A and B "exist concurrently", and B and C "exist concurrently", I would expect that also A and C "exist concurrently". But A and C may not be spacelike separated, A may be the past of C. One solution may be fatalism - the whole spacetime, past as well as future, "exist concurrently". The other one a preferred frame.

OK so the definition of existence between two events is really just a claim that there is ambiguity in their causal order. The ambiguity rests on which frame is making the proclamation. Events A and B exist concurrently from frame 1, where B and C would exist concurrently in frame 2, but neither frame 1 nor frame 2 could say that A and C exist concurrently because they are timelike separated.

None of this really applies to black holes, though, because crossing the event horizon is not spacelike separated from any frame at any point in the past or finite future.

 

[paddoboy]

Thanks. Broderick and Narayan I have already considered in http://arxiv.org/abs/1003.1446 and found that the weak point is their steady state assumption. Here, they make it again: "Thus, assuming that the system has reached steady state ...".

Some observations.
[1]Many papers have been printed supporting the existence of GR BH's and gravitationally completely collapsed objects according to the evidence available.
[2]Many scientific papers are accepted that specifically support or hypothesise
theoretical aspects of GR such as wormholes, ERB's, or even speculative issues such as parallel universes, ethers etc.

I'm not sure what the writes meant by "Steady State" as I have not read the full paper, but their argument is sound [as are the many others] supporting the existence of BH's.

 

[paddoboy]

None of this really applies to black holes, though, because crossing the event horizon is not spacelike separated from any frame at any point in the past or finite future.

It certainly though applies to such evidenced concepts such as the finite speed of light, time dilation and the validity of frames of references all being as valid as each other.

 

[brucep]

???? Not in GR with Minkowski spacetime interpretation. There you can use arbitrary coordinates x'(x) and transform any solution in any other coordinates x into a solution in new coordinates x'. The only thing which is fixed are rules to transform a solution in one set of coordinates into a solution in any other set. The coordinates may by arbitrary (ok, they have to be smooth, but that's all).

In GR SR is the special case where the effects of gravity can be ignored. This is pretty much in every local proper frame since GR predicts the local spacetime curvature is an infinitesimal. So when we need to account for infinitesimal effects of gravity, local spacetime curvature, we use the mathematics of GR. Such an experiment is the GPS or the Gravity Probe B. Minkowski wrote down his metric ten years before Einstein wrote down the field equations of GR. The fact that most the manifold can be evaluated using the mathematics of SR is pretty telling. The Minkowski metric would also be the metric at boundary. Far away in flat spacetime. To be honest I don't know what you mean with your first sentence.

 

[RJBeery]

It certainly though applies to such evidenced concepts such as the finite speed of light, time dilation and the validity of frames of references all being as valid as each other.

Yes, I'm not saying a frame experiencing the crossing of an event horizon is "invalid"; I'm saying it doesn't reside in any observers' past light cones. In fact, it only resides in future light cones of all observers, and one of the consequences of that is that the event horizon does not exist today, tomorrow, or the finite future. It's a simple argument.

And if we want to just start posting links rather than discussing the logic of the argument you may find this interesting:
http://news.nationalgeographic.com/...ole-stephen-hawking-firewall-space-astronomy/

 

[paddoboy]

Yes, I'm not saying a frame experiencing the crossing of an event horizon is "invalid"; I'm saying it doesn't reside in any observers' past light cones. In fact, it only resides in future light cones of all observers, and one of the consequences of that is that the event horizon does not exist today, tomorrow, or the finite future. It's a simple argument.

So? All frames are as valid as each other. Consider the delay in the data from the Mars orbiter data saying the lander was now released when if we were in the other frame of reference at Mars, it has already landed.
There is no universal now: What you appear to be on about is purely philosophical.

And if we want to just start posting links rather than discussing the logic of the argument you may find this interesting:
http://news.nationalgeographic.com/...ole-stephen-hawking-firewall-space-astronomy/

Who said posting links is not logical. I fail to see any logic in that argument at all.
It's the same argument I have had with a nutter who claims he is never wrong, but when reputable links are given to show he is wrong, he resorts to that nonsense. It's no more than a cop out.
And with regards to your link, If I recall correctly, in the past you have also argued on that point. In reality it does not invalidate GR BH's and is no more than a highly theoretical application of quantum effects that as yet we are somewhat ignorant of.
Here's another link......
http://www.pbs.org/newshour/updates/hawking-meant-black-holes/
some extracts
Last week, famed physicist Stephen Hawking made headlines with this bold statement: “there are no black holes.”

Those words come directly from Hawking’s latest paper, but they are contained within a larger point involving the mechanics of a black hole and its famous “event horizon.”

Last week, famed physicist Stephen Hawking made headlines with this bold statement: “there are no black holes.”

Those words come directly from Hawking’s latest paper, but they are contained within a larger point involving the mechanics of a black hole and its famous “event horizon.”

In a nutshell, Hawking seems to be saying this: instead of an event horizon, there is something else he calls an “apparent horizon.” In this apparent horizon, matter and energy is temporarily suspended, but then released. If this is true, it changes black holes as we know them.

 

[danshawen]

(Also posted this at Physicsforums.com but I don't think that's against the rules)

Over the years I've watched Science try to deal with the Information Paradox regarding black holes.

http://news.sciencemag.org/physics/2015/12/physicists-figure-out-how-retrieve-information-black-hole

I've always been curious how we got to the point where we see this as a problem in need of a solution. In order for information to be "in" a black hole, and theoretically unavailable to us, it must have crossed the event horizon from our perspective, correct?

We talk about the existence of black holes as a matter of fact, in present tense, but present tense existence of spatially distant objects (i.e. events) are space-like separated by any definition, and I don't think anyone will disagree with this. The temporal order of space-like separated events is ambiguous, and can be changed based on the frame of the observer. Now, follow this logic:

Let's denote an event a "growth event" when matter crosses an event horizon. In order for a black hole to presently exist with a non-zero radius for an observer, that observer must have "growth events" in his or her past light cone. The claim that a black hole currently exists for us fails on two counts: firstly because no such black hole growth events have occurred in any of our past light cones and, secondly, because there are no frames which can claim otherwise for us or themselves.

The typical response to this point is frame jumping by imagining ship A free-falling across an event horizon E with sufficiently low (survivable) tidal forces; however, this requires the existence of a black hole in the first place! We cannot use an imaginary black hole to prove the existence of theoretical black holes unless we are able to provide a theory of how they came to be in the first place. The problems faced by us on Earth would also exist for ship A; the existence of E could not be explained by any events in A's past light cone.

At this point, Kruskal (or some other) coordinates are dragged out. Again, there is no point to this. Kruskal coordinates are only needed to analyze anexisting black hole, and are not needed to discuss the birth of one. Additionally, no valid coordinate system (including Kruskal) can put growth events into the past light cone of any observer.

I don't mean to have a contentious tone, but I am frustrated by my inability to find someone who can convince me that black holes aren't a grand example of the Emperor having no clothes.

Oh, and MERRY CHRISTMAS!

HAPPY NEW YEAR!

Information does leave black holes, or at least the jets from their poles, from which they eventually completely evaporate. Recently, it has been discovered that the shock waves in these jets are processes which can modulate both gamma and radio emissions.

The annihilation jets can be part of the light cones of an observer outside and distant from the black hole, can't it? Also any Hawking radiation that has been produced from quantum effects going on near the event horizon.

And also other outside effects due to the presence of black holes that paddoboy has already mentioned. If you are orbiting one, you know it's there, even if you couldn't actually see it.

Any star "event" you can observe in the sky is coming from a "past light cone" and as such. are no different in terms of tests of reality than black holes, or for that matter our own Sun, which is something we see and feel real close up and personal, from a vantage point only about twenty light minutes in our past. I don't judge "reality" by means of Minkowski's stupid and useless light cones. Why would you? For one thing, there are just a whole lot more events going on outside of light cones than you will ever see inside. This does not mean that they are interior to black holes, only that information about them has radiated away from you in a direction you will never again see unless you catch a glimpse of those events reflected back towards you from a distant object.

 

[brucep]

So? All frames are as valid as each other. Consider the delay in the data from the Mars orbiter data saying the lander was now released when if we were in the other frame of reference at Mars, it has already landed.
There is no universal now: What you appear to be on about is purely philosophical.

Who said posting links is not logical. I fail to see any logic in that argument at all.
It's the same argument I have had with a nutter who claims he is never wrong, but when reputable links are given to show he is wrong, he resorts to that nonsense. It's no more than a cop out.
And with regards to your link, If I recall correctly, in the past you have also argued on that point. In reality it does not invalidate GR BH's and is no more than a highly theoretical application of quantum effects that as yet we are somewhat ignorant of.
Here's another link......
http://www.pbs.org/newshour/updates/hawking-meant-black-holes/
some extracts
Last week, famed physicist Stephen Hawking made headlines with this bold statement: “there are no black holes.”

Those words come directly from Hawking’s latest paper, but they are contained within a larger point involving the mechanics of a black hole and its famous “event horizon.”

Last week, famed physicist Stephen Hawking made headlines with this bold statement: “there are no black holes.”

Those words come directly from Hawking’s latest paper, but they are contained within a larger point involving the mechanics of a black hole and its famous “event horizon.”

In a nutshell, Hawking seems to be saying this: instead of an event horizon, there is something else he calls an “apparent horizon.” In this apparent horizon, matter and energy is temporarily suspended, but then released. If this is true, it changes black holes as we know them.

What he is getting at is r_s can dynamically change, + or - r, and that it isn't associated with unreal coordinates as in the classical theory. The apparent horizon is a light-like boundary which can be associated with an actual place in the universe.

 

[brucep]

HAPPY NEW YEAR!

Information does leave black holes, or at least the jets from their poles, from which they eventually completely evaporate. Recently, it has been discovered that the shock waves in these jets are processes which can modulate both gamma and radio emissions.

The annihilation jets can be part of the light cones of an observer outside and distant from the black hole, can't it? Also any Hawking radiation that has been produced from quantum effects going on near the event horizon.

And also other outside effects due to the presence of black holes that paddoboy has already mentioned. If you are orbiting one, you know it's there, even if you couldn't actually see it.

Any star "event" you can observe in the sky is coming from a "past light cone" and as such. are no different in terms of tests of reality than black holes, or for that matter our own Sun, which is something we see and feel real close up and personal, from a vantage point only about twenty light minutes in our past. I don't judge "reality" by means of Minkowski's stupid and useless light cones. Why would you? For one thing, there are just a whole lot more events going on outside of light cones than you will ever see inside. This does not mean that they are interior to black holes, only that information about them has radiated away from you in a direction you will never again see unless you catch a glimpse of those events reflected back towards you from a distant object.

Come on. Evaporates from jets. LOL. Something really useless is your illiterate comments .

 

[brucep]

Some observations.
[1]Many papers have been printed supporting the existence of GR BH's and gravitationally completely collapsed objects according to the evidence available.
[2]Many scientific papers are accepted that specifically support or hypothesise
theoretical aspects of GR such as wormholes, ERB's, or even speculative issues such as parallel universes, ethers etc.

I'm not sure what the writes meant by "Steady State" as I have not read the full paper, but their argument is sound [as are the many others] supporting the existence of BH's.

I think he might be confusing steady state with a classical static vacuum solution such as the metrics of GR? Hopefully I'm in error.

 

[danshawen]

Come on. Evaporates from jets. LOL. Something really useless is your illiterate comments .

Black holes evaporate in cosmological time in this way. From the black holes that are at the centers of every galaxy in this universe, right here, right now. I understand your frustration with this thread however. Not enough deep cosmology in it, I agree.

Light cones are interpreted as a cone on the bottom that represents the past connected at the vertex (present) with an inverted future light cone in spacetime. Any event that lies outside of the light cones is never observed in the past, present, or future.

Let's say for the sake of argument that the present event is you turning on a laser pointer for an instant inside of an opaque box. Explain to us how an understanding of light cones is of any predictive value or consequence about this event to anyone, anywhere, under any circumstances in this universe. That is my working definition of useless. It goes nowhere and helps us understand nothing. Perhaps this is what the OP was getting at.

 

[Schmelzer]

None of this really applies to black holes, though, because crossing the event horizon is not spacelike separated from any frame at any point in the past or finite future.

To talk about frames in a GR context makes no sense. But there are points behind the horizon which are space-like separated from points outside.

To be honest I don't know what you mean with your first sentence.

I was objecting to "The coordinates are solutions to field equations.". But this would be true in my ether interpretation for the preferred coordinates, which would be harmonic, so, solutions of field equations. So, to avoid confusion, I have added to "GR" the specification that this holds in its standard interpretation, which is the Minkowski spacetime interpretation. Which Minkowski invented for SR, but has been used in GR too.

 

[origin]

Black holes evaporate in cosmological time in this way. From the black holes that are at the centers of every galaxy in this universe, right here, right now. I understand your frustration with this thread however. Not enough deep cosmology in it, I agree.

The frustration is probably due to guys like you just making up stuff. For instance, the matter in the jets does not come from inside the event horizon so it is impossible that a black hole could evaporate from jets.

 

[danshawen]

The frustration is probably due to guys like you just making up stuff. For instance, the matter in the jets does not come from inside the event horizon so it is impossible that a black hole could evaporate from jets.

Interesting if true. So, the three or four popular references I read on the subject of black hole jets were in error? That would explain a lot, but as I understand it, the jets are not comprised of what is referred to as Hawking radiation. Is this wrong, or just another source of speculation? I know there are black hole deniers. I have met a few. RJBeary seems to be one, but his mode of "proof" is eccentric, to say the least.

So, can anyone direct me to a reference about the jets that is the mainstream view?

If the jets are not sourced from inside, how can black holes be said to evaporate in cosmological time? Or is this also not a mainstream view?

 

[The God]

Black holes evaporate in cosmological time in this way.

No they don't and they cannot. What is cosmological time, say what any clock outside BH (This side of EH) would tick/measure. Now please refer to gravitational time dilation, as soon as EH is formed due to collapsing star, the BH is born (Rjbeery t = 0), now if there is a clock on the collapsing star then any infinitessimally small tick on it will be equal to eternity for cosmological clock. so a BH cannot evaporate in cosmological time. lets be fair to BH man, if the kid grow even by a tick, this side is vanished.

PS: requet please let us not clutter this thread by bringing in HR.

(Also posted this at Physicsforums.com but I don't think that's against the rules)

Over the years I've watched Science try to deal with the Information Paradox regarding black holes.

http://news.sciencemag.org/physics/2015/12/physicists-figure-out-how-retrieve-information-black-hole

I've always been curious how we got to the point where we see this as a problem in need of a solution. In order for information to be "in" a black hole, and theoretically unavailable to us, it must have crossed the event horizon from our perspective, correct?

We talk about the existence of black holes as a matter of fact, in present tense, but present tense existence of spatially distant objects (i.e. events) are space-like separated by any definition, and I don't think anyone will disagree with this. The temporal order of space-like separated events is ambiguous, and can be changed based on the frame of the observer. Now, follow this logic:

Let's denote an event a "growth event" when matter crosses an event horizon. In order for a black hole to presently exist with a non-zero radius for an observer, that observer must have "growth events" in his or her past light cone. The claim that a black hole currently exists for us fails on two counts: firstly because no such black hole growth events have occurred in any of our past light cones and, secondly, because there are no frames which can claim otherwise for us or themselves.

The typical response to this point is frame jumping by imagining ship A free-falling across an event horizon E with sufficiently low (survivable) tidal forces; however, this requires the existence of a black hole in the first place! We cannot use an imaginary black hole to prove the existence of theoretical black holes unless we are able to provide a theory of how they came to be in the first place. The problems faced by us on Earth would also exist for ship A; the existence of E could not be explained by any events in A's past light cone.

At this point, Kruskal (or some other) coordinates are dragged out. Again, there is no point to this. Kruskal coordinates are only needed to analyze anexisting black hole, and are not needed to discuss the birth of one. Additionally, no valid coordinate system (including Kruskal) can put growth events into the past light cone of any observer.

I don't mean to have a contentious tone, but I am frustrated by my inability to find someone who can convince me that black holes aren't a grand example of the Emperor having no clothes.

Oh, and MERRY CHRISTMAS!

partly this is answered above. Growth (ageing) is meaningful in ones clock. Our age on a clock at collapsing star (inside its Rs) is not even a tiny fraction, and similarly a tiny fraction on a clock inside EH is eternity for us. So growth of BH is well..you know what. You grow only if you are there.

Let me put it differently, constancy of light speed is axiomatic, but it gives a nice relative motion based time dilation formula which has term SQRT(1-v^2/c^2), the maths go haywire if we try v > c in this formula...quite interesting...similarly the gravitational time dilation has a term Sqrt (1-Rs/r), here also maths go haywire if we try Rs > r. If v cannot be greater than c, then surely r also cannot be less than Rs. Allow that and all sort of bizzare nonsense appears. And BH is one such.

 

[Schmelzer]

So, the three or four popular references I read on the subject of black hole jets were in error?

If they have written that jets come from inside, obviously.

If the jets are not sourced from inside, how can black holes be said to evaporate in cosmological time? Or is this also not a mainstream view?

The mainstream view is that they evaporate because of Hawking radiation, and the time scale for this is unimaginable large, so, even if it is not completely clear to me what you mean with "cosmological time", I can nonetheless say without much risk that it is much larger.