Why would he have to?
The argument and observational evidence is well known.
And that wasn't my question.
QM + GR = black holes cannot exist
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Why would he have to?
The argument and observational evidence is well known.
And that wasn't my question.
And in any respect, if you have followed the thread, its as plain as day the brucep and Declan have given quite substantial arguments for the reality of BH's that have not been refuted by any means.
I'm green, so I don't always get it. 
r=0 is the origin of the singularity, while the radius of the (classical) EH is dependent on the mass of the (assumed) singularity (according to the current mainstream interpretation of the best models we have that are observationally consistent), yes?
r=0 is the origin of the singularity, while the radius of the (classical) EH is dependent on the mass of the (assumed) singularity (according to the current mainstream interpretation of the best models we have that are observationally consistent), yes?
I'm green, so I don't always get it.
r=0 is the origin of the singularity, while the radius of the (classical) EH is dependent on the mass of the (assumed) singularity (according to the current mainstream interpretation of the best models we have that are observationally consistent), yes?
I'd say yes with the exception of the existence of the singularity itself.
r=0 assumes a point mass. While no issue arises mathematically by treating a black hole as a point singularity, because for all intents and purposes we model all stellar objects as point mass objects.., such that in terms of the associated gravitational field the center of mass of any massive object is the focal origin the gravitational field. True dimensions are only an issue when we are dealing with forces present at the surface or within the physical radius of a gravitationally significant object.., and for a black hole that would lie within the EH. And within the EH is where theory takes over, because what we are able to observe lies outside the EH.
I did say assumed singularity. I'm trying to play avocatus sancti here...
Ah, I missed that.
You may have noticed that the most common choice for this type of analysis is the Schwarzschild geometry. It was the first metric solution to Einsteins famous field equations. It's an idealized geometry spherically symmetric and non rotating. For this geometry r=0 is the exact center of a spherically symmetric non rotating mass. IE the black hole. It's different for rotating and charged black holes. I know you've heard of the ring singularity. For rotating black holes we can't use r=0 to describe where the singularity forms. The easy way to get the radius for nM_solar mass is to factor the number of solar mass to the length of one solar mass (1477meter). So for the earlier exampleI'm green, so I don't always get it.
r=0 is the origin of the singularity, while the radius of the (classical) EH is dependent on the mass of the (assumed) singularity (according to the current mainstream interpretation of the best models we have that are observationally consistent), yes?
4,500,000 solar mass x 1477m = 6,646,500,000m
r=2M = 2954m for a solar mass black hole. It's common to use these geometricized units when dealing with geometric spacetime.
That's not what Bee said in the blogspot you reference:
"Hawking radiation has a negative energy-component. Normally negative energies are actually anti-particles with positive energies, but not so in the black hole evaporation. The negative energy particles though only exist inside the horizon. Now in Laura’s paper, the negative energy particles exist inside the collapsing matter, but outside the horizon. Next, she doesn’t integrate the mass loss over time and subtracts this from the initial mass, but integrates the negative energies over the inside of the mass and subtracts this integral from the initial mass. At least that is my reading of Equation IV.10 in 1406.1525, and equation 11e in 1409.1837 respectively. Note that there is no time-integration in these expressions which puzzles me."
This is the logical extrapolation of Hawking's conjecture of "negative mass" (negative energy), for which there is no physical counterpart. This is not virtual particle/anti-particle (with no net mass energy unless it is interjected into the pair, and they become real), but a conjecture used to support his original hypothesis; a conjecture for which there is no actual physical counterpart and appears wholly unsupported. Using that reasoning, one can conclude that black holes won't form. But since they do form, that reasoning is not correct.
There's no need to ask the community what the general consensus is; it's well-known that black holes are assumed to exist by most, just like luminiferous aether was in the past. The general consensus has no ultimate baring on the nature of reality.
Mr. Tully did not technically endorse any position, he simply stated what many thought; he also did not even bother to read the paper referenced in the OP. If you want to consider this a "win" for you then, by all means, go for it. I'm not here to persuade stubborn minds, I'm here to bring clarity to my own convictions, or change them if needed.
I agree.
Just curious to see what he had to say. One wonders why as a scientist in that field, he had not read the paper.
And of course this little bit of "creative sensansionalism" was shown to be exactly what it is by brucep and Declan further back.
A real "nothing to see here", move on" moment.
That's not correct. Luminiferous aether was invented out of classical mechanics, to explain phenomena for which there was no other science. The juxtaposition of two discoveries: -- the constancy of c and the laws of electromagnetics -- made aether irrelevant. Black hole theory did originally rely on the corpuscular theory of light, which would render it moot today, if not for the newly evolved version of it explained by Hawking in 1962. Unlike aether theory, which never stood the test of empirical measurement, black hole theory has been corroborated by discoveries such as those I posted above.
But you aren't arguing against black holes. So far you have admitted that supermassive objects can be optically transparent. And no one has yet explained what to do with the empirical evidence for black holes that I posted above, in the eventuality that general consensus were reached solely on the basis of the paper you cited. Are we supposed to ignore the rest of the evidence, bury it, or do what the ICR does, which is to manufacture excuses?
Yes, there is consensus: wherever there is evidence, and wherever there is scholarship that best explains it.
Au contraire, the "nature of reality" in scientific consensus is grounded in empirical evidence.
Is that why you are here? Or are you here for any of the following reasons:
(a) You are here to demonstrate a form of argumentation which relies on facts outside of the body of evidence, incomplete facts, and facts which ignore the evidence. That much is obvious. Less obvious is why you feel the need to do this with only a pedestrian background in this, one of the most advanced topics in science.
(b) You are here to propound your angst against scientific consensus, without explaining what you plan to do about all the consensus which you no doubt agree with. You've created a logical inconsistency in attacking consensus. And you've opened yourself to attack on grounds of naive narcissism.
(c) You are here to attack science. But why? Only three species of minds known to me are prone to do this: (1) the post-modernist (2) the creationist and (3) the psychopathic personality type, to include most cranks and trolls.
(b) You are here to propound your angst against scientific consensus, without explaining what you plan to do about all the consensus which you no doubt agree with. You've created a logical inconsistency in attacking consensus. And you've opened yourself to attack on grounds of naive narcissism.
(c) You are here to attack science. But why? Only three species of minds known to me are prone to do this: (1) the post-modernist (2) the creationist and (3) the psychopathic personality type, to include most cranks and trolls.
I meant to say 1965. (No editing of posts anymore? I'm doomed!)
And for clarification, the "newly evolved" explanation was much bigger than what is directly being attacked in this thread. The young Hawking related black holes to Big Bang theory. To attack Hawking, and to attack the existence of black holes, is to attack the scientific position that the universe created itself.
Yes, Virginia, There Are Black Holes:
Recent headlines have proclaimed “Black Holes Don’t Exist!” They’re wrong. Black holes absolutely exist. We know this observationally. We know by the orbits of stars in the center of our galaxy that there is a supermassive black hole in its center. We know of binary black hole systems. We’ve found the infrared signatures of more than a million black holes. We know of stellar mass black holes, and intermediate mass black holes. We can even see a gas cloud ripped apart by the intense gravity of a black hole. And we can take images of black holes, such as the one above. Yes, Virginia, there are black holes.
So what’s with the headlines? It seems to start with a link-bait article about a new work concerning the formation of stellar mass black holes. The paper hasn’t been peer reviewed, but it is an extension of an earlier work by the same authors that has been peer reviewed. The focus of both of these papers is on the firewall paradox, specifically how Hawking radiation might affect the gravitational collapse of a star to form a black hole.
The firewall paradox is something that arises when you try to combine black holes with quantum theory. In quantum theory there are limits to what can be known about an object. For example, you cannot know an object’s exact energy. Because of this uncertainty, the energy of a system can fluctuate spontaneously, so long as its average remains constant. In 1974 Stephen Hawking demonstrated is that near the event horizon of a black hole pairs of particles can appear, where one particle becomes trapped within the event horizon (reducing the black holes mass slightly) while the other can escape as radiation (carrying away a bit of the black hole’s energy). These escaping particles have come to be known as Hawking radiation.
According to general relativity, if you were to fall into a black hole, you shouldn’t notice anything strange when you cross the event horizon. Yes, you might feelstrong tidal forces, but you’d feel those outside the black hole as well. But according to quantum theory if all this Hawking radiation is being created near the event horizon, then you should experience a firewall of quantum particles. The solution to this theoretical problem is still a matter of some debate. Some, such as Hawking and the authors of this new paper, feel that the Hawking firewall prevents black hole horizons from forming. Others, such as Sabine Hossenfelder argue that quantum theory doesn’t lead to a Hawking firewall. Just to be clear, I’m personally in the Hossenfelder camp.
In this new paper, the authors show that if the Hawking firewall idea is correct, then as a star starts collapsing at the end of its life, before it collapses into a black hole Hawking radiation starts kicking in, which pushes back against the collapsing star. So instead of collapsing into a solar-mass black hole, the star almost collapses into a black hole, Hawking radiation stops its collapse, and the stellar core then explodes. So the star dies in a supernova explosion, but no black hole is formed from its core.
This is interesting theoretical work, and it raises questions about the formation of stellar-mass black holes. But it doesn’t prove that stellar-mass black holes don’t exist, nor does it say anything about intermediate mass or supermassive black holes, which would form by processes other than stellar collapse. And of course the work depends upon Hawking’s take on firewalls to be correct, which hasn’t been proven. To say that this work proves black holes don’t exist is disingenuous at best.
So don’t buy into the hype. Black holes are real, this work is interesting, and the link-baiters should be ashamed of themselves.
https://briankoberlein.com/2014/09/25/yes-virginia-black-holes/
Recent headlines have proclaimed “Black Holes Don’t Exist!” They’re wrong. Black holes absolutely exist. We know this observationally. We know by the orbits of stars in the center of our galaxy that there is a supermassive black hole in its center. We know of binary black hole systems. We’ve found the infrared signatures of more than a million black holes. We know of stellar mass black holes, and intermediate mass black holes. We can even see a gas cloud ripped apart by the intense gravity of a black hole. And we can take images of black holes, such as the one above. Yes, Virginia, there are black holes.
So what’s with the headlines? It seems to start with a link-bait article about a new work concerning the formation of stellar mass black holes. The paper hasn’t been peer reviewed, but it is an extension of an earlier work by the same authors that has been peer reviewed. The focus of both of these papers is on the firewall paradox, specifically how Hawking radiation might affect the gravitational collapse of a star to form a black hole.
The firewall paradox is something that arises when you try to combine black holes with quantum theory. In quantum theory there are limits to what can be known about an object. For example, you cannot know an object’s exact energy. Because of this uncertainty, the energy of a system can fluctuate spontaneously, so long as its average remains constant. In 1974 Stephen Hawking demonstrated is that near the event horizon of a black hole pairs of particles can appear, where one particle becomes trapped within the event horizon (reducing the black holes mass slightly) while the other can escape as radiation (carrying away a bit of the black hole’s energy). These escaping particles have come to be known as Hawking radiation.
According to general relativity, if you were to fall into a black hole, you shouldn’t notice anything strange when you cross the event horizon. Yes, you might feelstrong tidal forces, but you’d feel those outside the black hole as well. But according to quantum theory if all this Hawking radiation is being created near the event horizon, then you should experience a firewall of quantum particles. The solution to this theoretical problem is still a matter of some debate. Some, such as Hawking and the authors of this new paper, feel that the Hawking firewall prevents black hole horizons from forming. Others, such as Sabine Hossenfelder argue that quantum theory doesn’t lead to a Hawking firewall. Just to be clear, I’m personally in the Hossenfelder camp.
In this new paper, the authors show that if the Hawking firewall idea is correct, then as a star starts collapsing at the end of its life, before it collapses into a black hole Hawking radiation starts kicking in, which pushes back against the collapsing star. So instead of collapsing into a solar-mass black hole, the star almost collapses into a black hole, Hawking radiation stops its collapse, and the stellar core then explodes. So the star dies in a supernova explosion, but no black hole is formed from its core.
This is interesting theoretical work, and it raises questions about the formation of stellar-mass black holes. But it doesn’t prove that stellar-mass black holes don’t exist, nor does it say anything about intermediate mass or supermassive black holes, which would form by processes other than stellar collapse. And of course the work depends upon Hawking’s take on firewalls to be correct, which hasn’t been proven. To say that this work proves black holes don’t exist is disingenuous at best.
So don’t buy into the hype. Black holes are real, this work is interesting, and the link-baiters should be ashamed of themselves.
https://briankoberlein.com/2014/09/25/yes-virginia-black-holes/
tashja
Registered Senior Member
Hi guys. Let me begin by assuring you that the reply I posted from Prof. Laura is legit. I don't wish to stir up polemic here, and I would never invent such a thing. You guys are welcome to correspond with her just as I did. Having said that, and for the benefit of our discussion here, I took it upon myself to get a 'second opinion' from an expert in the field that has actually reviewed and cited Prof. Laura & Harald Pfeiffer's paper in her own work (http://arxiv.org/abs/arXiv:1409.4031). I quoted Paddoboy and RJBeery's questions in the email and let her know that the inquiries were from members of the forum. This is her reply:
Declan Lunny
Registered Senior Member
One of those are you? I call BS.
Here are the trajectories of the stars in the central parsec of our galaxy observed from 1995-2013. The five-pointed star locates "Sagittarius A-star" (Sgt A*) which is near the center, orbiting a radius about the size of Neptune. The mass needed to support these orbits is about 4.5 million solar masses. When we talk about that much mass in the volume of, say, Neptune, we are talking about a supermassive black hole.
Declan Lunny
Registered Senior Member
A partial retraction but still calling BS.
You did communicate with Francesca Vidotto, but you seem to be channeling through the aether while quoting her. She was not quite the verbose. Laura Mersin-Houghton still has not replied to you, so that seems to be more aether channeling on your part.
When using name dropping for gravitas, be careful that someone who overhears your conversation can not speak directly to the name you are dropping.
tashja
Registered Senior Member
Declan, all the emails/replies are posted verbatim. I have not changed or added anything. I couldn't even if I wanted to because I don't possess the knowledge or the intentions. I'm doing this for the benefit of the topic. If I'm misquoting the authors of those emails, then let them come here and launch a formal complaint with the site authorities.
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