in 2014
This Physicist Says She Has Proof Black Holes Simply Don’t Exist

and more recently Richard Muller, who seems to be a reputable physicist said:
Most theorists would dismiss such a contention, but that doesn’t mean that most physicists are right.

My opinion? I don’t have one. I think we should be respectful of the iconoclasts, however. Consensus is an unreliable indicator of correct science.
https://www.quora.com/A-group-of-physicists-say-they-concluded-definitively-that-black-holes-don%E2%80%99t-exist-How-does-this-change-our-understanding-of-the-universe

So how come no-one told me this was even a possibility?

And what are all those pictures of that claim to be black holes, if not black holes?

The Rev Dodgson said:

in 2014
This Physicist Says She Has Proof Black Holes Simply Don’t Exist

and more recently Richard Muller, who seems to be a reputable physicist said:
Most theorists would dismiss such a contention, but that doesn’t mean that most physicists are right.

My opinion? I don’t have one. I think we should be respectful of the iconoclasts, however. Consensus is an unreliable indicator of correct science.
https://www.quora.com/A-group-of-physicists-say-they-concluded-definitively-that-black-holes-don%E2%80%99t-exist-How-does-this-change-our-understanding-of-the-universe

So how come no-one told me this was even a possibility?

And what are all those pictures of that claim to be black holes, if not black holes?

They apparently are places where light does not only not exist to be seen but cannot even be imaged from any angle

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

Try asking for a rubber in an American classroom?

Laura Mersini-Houghton

>With Stephen Hawking, she organized a historic conference in 2015 in Stockholm to discuss these fundamental topics.

https://en.wikipedia.org/wiki/Laura_Mersini-Houghton

Seems not much eventuated from these musings :)

Have to agree with her critics that the empirical evidence for gravitationally collapsed entities known as black holes is now fully entrenched.

But a precise and thorough theoretical description of these objects remains elusive.

Bubblecar said:

Laura Mersini-Houghton

>With Stephen Hawking, she organized a historic conference in 2015 in Stockholm to discuss these fundamental topics.

https://en.wikipedia.org/wiki/Laura_Mersini-Houghton

Seems not much eventuated from these musings :)

Have to agree with her critics that the empirical evidence for gravitationally collapsed entities known as black holes is now fully entrenched.

But a precise and thorough theoretical description of these objects remains elusive.

It’s interesting that Richard Muller is not willing to totally dismiss the idea though (although that comment was from 2018, so he may have changed his mind by now though).

The Rev Dodgson said:

in 2014
This Physicist Says She Has Proof Black Holes Simply Don’t Exist

and more recently Richard Muller, who seems to be a reputable physicist said:
Most theorists would dismiss such a contention, but that doesn’t mean that most physicists are right.

My opinion? I don’t have one. I think we should be respectful of the iconoclasts, however. Consensus is an unreliable indicator of correct science.
https://www.quora.com/A-group-of-physicists-say-they-concluded-definitively-that-black-holes-don%E2%80%99t-exist-How-does-this-change-our-understanding-of-the-universe

So how come no-one told me this was even a possibility?

And what are all those pictures of that claim to be black holes, if not black holes?

This is the result of numerical modelling, rather than what I would term a “proof”. It’s not unusual for different modelling efforts to produce different results, and even for some outliers to pop up, but if the results are at odds with the physical evidence, it just means you haven’t restrained your model properly.

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

It’s not an assumption, it is an intrinsic aspect of quantum mechanics. We measure the quantum state of a system as a probability. The sum of all possible states of the system must be equal to 1; in other words there is a 100% chance that the system exists in one of the possible states it could exist in. However, if information is lost or destroyed, then the probability of the system existing in any one of those states would be less than 1, which would violate the fundamental principle of unitarity.

https://www.hellenicaworld.com/Science/Physics/en/UnitaritPhysics.html
In quantum physics, unitarity is the condition that the time evolution of a quantum state according to the Schrödinger equation is mathematically represented by a unitary operator. This is typically taken as an axiom or basic postulate of quantum mechanics, while generalizations of or departures from unitarity are part of speculations about theories that may go beyond quantum mechanics.

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

LPITW, information destruction in this sense would mean scrapping the Schrodinger Wave Equation, which would be a shame because it works so well.

esselte said:

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

It’s not an assumption, it is an intrinsic aspect of quantum mechanics. We measure the quantum state of a system as a probability. The sum of all possible states of the system must be equal to 1; in other words there is a 100% chance that the system exists in one of the possible states it could exist in. However, if information is lost or destroyed, then the probability of the system existing in any one of those states would be less than 1, which would violate the fundamental principle of unitarity.

https://www.hellenicaworld.com/Science/Physics/en/UnitaritPhysics.html
In quantum physics, unitarity is the condition that the time evolution of a quantum state according to the Schrödinger equation is mathematically represented by a unitary operator. This is typically taken as an axiom or basic postulate of quantum mechanics, while generalizations of or departures from unitarity are part of speculations about theories that may go beyond quantum mechanics.

The quote says the principle is “an axiom or basic postulate”, and these are alternative names for “assumption”.

The Rev Dodgson said:

esselte said:

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

It’s not an assumption, it is an intrinsic aspect of quantum mechanics. We measure the quantum state of a system as a probability. The sum of all possible states of the system must be equal to 1; in other words there is a 100% chance that the system exists in one of the possible states it could exist in. However, if information is lost or destroyed, then the probability of the system existing in any one of those states would be less than 1, which would violate the fundamental principle of unitarity.

https://www.hellenicaworld.com/Science/Physics/en/UnitaritPhysics.html
In quantum physics, unitarity is the condition that the time evolution of a quantum state according to the Schrödinger equation is mathematically represented by a unitary operator. This is typically taken as an axiom or basic postulate of quantum mechanics, while generalizations of or departures from unitarity are part of speculations about theories that may go beyond quantum mechanics.

The quote says the principle is “an axiom or basic postulate”, and these are alternative names for “assumption”.

Quantum mechanics would break without that axiom. Quantum mechanics has proven to be experimentally robust.

dv said:

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

LPITW, information destruction in this sense would mean scrapping the Schrodinger Wave Equation, which would be a shame because it works so well.

We have no idea if it works at all when stuff interacts with black holes, if there are black holes.

Outside black holes you can keep using it to your heart’s content.

esselte said:

The Rev Dodgson said:

esselte said:

It’s not an assumption, it is an intrinsic aspect of quantum mechanics. We measure the quantum state of a system as a probability. The sum of all possible states of the system must be equal to 1; in other words there is a 100% chance that the system exists in one of the possible states it could exist in. However, if information is lost or destroyed, then the probability of the system existing in any one of those states would be less than 1, which would violate the fundamental principle of unitarity.

https://www.hellenicaworld.com/Science/Physics/en/UnitaritPhysics.html
In quantum physics, unitarity is the condition that the time evolution of a quantum state according to the Schrödinger equation is mathematically represented by a unitary operator. This is typically taken as an axiom or basic postulate of quantum mechanics, while generalizations of or departures from unitarity are part of speculations about theories that may go beyond quantum mechanics.

The quote says the principle is “an axiom or basic postulate”, and these are alternative names for “assumption”.

Quantum mechanics would break without that axiom. Quantum mechanics has proven to be experimentally robust.

We have precisely zero experimental evidence for how things work inside black holes.

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

LPITW, information destruction in this sense would mean scrapping the Schrodinger Wave Equation, which would be a shame because it works so well.

We have no idea if it works at all when stuff interacts with black holes, if there are black holes.

Outside black holes you can keep using it to your heart’s content.

Right but we’d need to come up with some modification to allow for the boundary condition. It’s too much hard work.

dv said:

The Rev Dodgson said:

dv said:

LPITW, information destruction in this sense would mean scrapping the Schrodinger Wave Equation, which would be a shame because it works so well.

We have no idea if it works at all when stuff interacts with black holes, if there are black holes.

Outside black holes you can keep using it to your heart’s content.

Right but we’d need to come up with some modification to allow for the boundary condition. It’s too much hard work.

In that case shouldn’t we describe the boundaries of black holes (if they exist) as something we know nothing about, rather than saying they are paradoxical?

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

We have no idea if it works at all when stuff interacts with black holes, if there are black holes.

Outside black holes you can keep using it to your heart’s content.

Right but we’d need to come up with some modification to allow for the boundary condition. It’s too much hard work.

In that case shouldn’t we describe the boundaries of black holes (if they exist) as something we know nothing about, rather than saying they are paradoxical?

The fundamental point you are making is reasonable. These issues are not so much paradoxical as they are interesting and counteraxiomatic.

dv said:

The Rev Dodgson said:

dv said:

Right but we’d need to come up with some modification to allow for the boundary condition. It’s too much hard work.

In that case shouldn’t we describe the boundaries of black holes (if they exist) as something we know nothing about, rather than saying they are paradoxical?

The fundamental point you are making is reasonable. These issues are not so much paradoxical as they are interesting and counteraxiomatic.

So we are all agreed then :)

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

In that case shouldn’t we describe the boundaries of black holes (if they exist) as something we know nothing about, rather than saying they are paradoxical?

The fundamental point you are making is reasonable. These issues are not so much paradoxical as they are interesting and counteraxiomatic.

So we are all agreed then :)

I admit we are fine and important fellows but it might be unfair to call us “all”.

dv said:

The Rev Dodgson said:

dv said:

The fundamental point you are making is reasonable. These issues are not so much paradoxical as they are interesting and counteraxiomatic.

So we are all agreed then :)

I admit we are fine and important fellows but it might be unfair to call us “all”.

Near enough for me :)

I’m off to claim some money.

I agree that the experts don’t yet fully understand black holes, so it’s not surprising that humble citizens like myself and B.C. don’t either.

Bubblecar said:

I agree that the experts don’t yet fully understand black holes, so it’s not surprising that humble citizens like myself and B.C. don’t either.

….B.C. was of course the insatiable black hole enthusiast on the old forum.

Wonder if he’s still going.

if BH don’t exist then the objects we have imaged that we call BH must be something else and if they exhibit the properties of objects we call BH then we may as well call them BH.

ChrispenEvan said:

if BH don’t exist then the objects we have imaged that we call BH must be something else and if they exhibit the properties of objects we call BH then we may as well call them BH.

That’s why I was surprised to read that apparently reputable physicists were at least open to the possibility they don’t exist.

But that was last decade.

The Rev Dodgson said:

esselte said:

The Rev Dodgson said:

The quote says the principle is “an axiom or basic postulate”, and these are alternative names for “assumption”.

Quantum mechanics would break without that axiom. Quantum mechanics has proven to be experimentally robust.

We have precisely zero experimental evidence for how things work inside black holes.

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

esselte said:

The Rev Dodgson said:

esselte said:

Quantum mechanics would break without that axiom. Quantum mechanics has proven to be experimentally robust.

We have precisely zero experimental evidence for how things work inside black holes.

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Since we know that existing physics is inadequate to fully model what’s going on in black holes, it’s more a matter of ignorance than paradox.

Bubblecar said:

esselte said:

The Rev Dodgson said:

We have precisely zero experimental evidence for how things work inside black holes.

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Since we know that existing physics is inadequate to fully model what’s going on in black holes, it’s more a matter of ignorance than paradox.

A paradox does not have to be contradictory, it is enough that it appears to be contradictory. If it appears contradictory because of ignorance, then it is a paradox caused by ignorance. It’s still a paradox though. Regardless of the cause, a paradox remains a paradox as long as it appears to be contradictory or paradoxical, even if the resolution is ultimately found to be based on a lack of information or understanding.

1

one (such as a person, situation, or action) having seemingly contradictory qualities or phases
2
a

a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true
b

a self-contradictory statement that at first seems true
c

an argument that apparently derives self-contradictory conclusions by valid deduction from acceptable premises
3

a tenet contrary to received opinion

esselte said:

The Rev Dodgson said:

esselte said:

Quantum mechanics would break without that axiom. Quantum mechanics has proven to be experimentally robust.

We have precisely zero experimental evidence for how things work inside black holes.

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Only if you assume that QM theory should be applicable inside black holes, which is just silly.

Well, the thing about a black hole – its main distinguishing feature – is it’s black. And the thing about space, the colour of space, your basic space colour, is black. So how are you supposed to see them?

The Rev Dodgson said:

esselte said:

The Rev Dodgson said:

We have precisely zero experimental evidence for how things work inside black holes.

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Only if you assume that QM theory should be applicable inside black holes, which is just silly.

It’s Hawking’s fault. He’s the one that convinced the world that black holes can evaporate and that when they do so they will not release the information contained inside them. Assuming Hawking is correct, the best explanation for the information being lost is that QM unitarity fails inside a black hole. It’s expected that QM theory is not applicable inside black holes, but this is not an assumption, its a deduction based on Hawking’s work.

The Rev Dodgson said:

esselte said:

The Rev Dodgson said:

We have precisely zero experimental evidence for how things work inside black holes.

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Only if you assume that QM theory should be applicable inside black holes, which is just silly.

Well now it seems we are not even in agreement about what a paradox is

esselte said:

The Rev Dodgson said:

esselte said:

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Only if you assume that QM theory should be applicable inside black holes, which is just silly.

It’s Hawking’s fault. He’s the one that convinced the world that black holes can evaporate and that when they do so they will not release the information contained inside them. Assuming Hawking is correct, the best explanation for the information being lost is that QM unitarity fails inside a black hole. It’s expected that QM theory is not applicable inside black holes, but this is not an assumption, its a deduction based on Hawking’s work.

Here’s the full text from the Richard Muller link in the OP, which is sort of relevant:

Classical black holes, formed by collapsing matter, don’t exist—because it takes forever for them to form. Yes, they form quickly in the co-moving frame of the falling matter, but in our distant Earth frame, they take forever.

The story changes when you include quantum effects. Even in our Earth frame, forming black holes rapidly reach the point where quantum effects at the Schwarzschild radius become very important. From such arguments, we can argue that the difference between a new black hole and one which is primordial (i.e. existed from the beginning) is indistinguishable in a fundamental way. Thus, we conclude, black holes do exist.

Some might argue that our knowledge of quantum effects in this high gravity regime is still speculative, and that is true. Hawking radiation, for example, has never been observed either directly or indirectly. (Some people think that’s why Hawking never got a Nobel Prize.) So if someone argues, using quantum theory, that black holes do not exist, then it is hard to counter them. Most theorists would dismiss such a contention, but that doesn’t mean that most physicists are right.

My opinion? I don’t have one. I think we should be respectful of the iconoclasts, however. Consensus is an unreliable indicator of correct science.

dv said:

The Rev Dodgson said:

esselte said:

The paradox arises because QM and General Relativity contradict each other. QM says information should never be lost. GR says information becomes unavailable when it is consumed by a black hole. As the black hole evaporates we might expect that information to be released back in to the wild, to become available again, but the current understanding of black hole evaporation does not support this idea. Rather, the information is lost for ever. They can not both be correct, hence the paradox.

Note that a paradox as defined in this usage is a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory. In this case, two apparently accurate premises (GR and QM) give contradictory conclusions.

The paradox can be resolved by either improving or replacing QM theory or black hole evaporation theory. Until then, it is still a paradox though.

Only if you assume that QM theory should be applicable inside black holes, which is just silly.

Well now it seems we are not even in agreement about what a paradox is

Here’s what I think on that:

True paradoxes are impossible, by definition, so all paradoxes are apparent paradoxes.

They have a resolution, we just don’t know what it is (or people can’t agree what it is).

So the question is, when does a lack of knowledge become a paradox.

I’d say it does when we have good reason to think that all the statements leading to the paradox are valid.

So any statement based on QM (as we understand it) being valid inside a black hole cannot be a paradox.

The Rev Dodgson said:

So the question is, when does a lack of knowledge become a paradox.

I’d say it does when we have good reason to think that all the statements leading to the paradox are valid.

So any statement based on QM (as we understand it) being valid inside a black hole cannot be a paradox.

But that IS the paradox. QM is a universal theory, it should be valid in all physical systems. The question is, why does it not work inside black holes? The answer is because black holes are lots and lots of gravity, and our understanding of gravity is based on GR, not QM. We do not currently have a working theory of quantum gravity. GR and QM are fundamentally incompatible. We notice it at black holes because there is a big concentration of gravity there, but like QM, GR is a universal theory. There is QM and GR everywhere, “describing” (with astonishing mathematical accuracy in both cases) how the universe works, but they are incompatible with each other. One of the ways they are incompatible is that QM says information can not be destroyed, whilst GR destroys information any time gravity is concentrated in a black-hole-ish-like way. This is the paradox. Two universally applicable robust theories that are incompatible with one another in regards to the conclusions drawn about the permanence of information.

Why do you think QM should not be valid inside a black hole? You called it a silly idea earlier. What’s silly about the idea that QM should work inside black holes? Separately from the fact that GR says it does not work, I mean.

esselte said:

The Rev Dodgson said:

So the question is, when does a lack of knowledge become a paradox.

I’d say it does when we have good reason to think that all the statements leading to the paradox are valid.

So any statement based on QM (as we understand it) being valid inside a black hole cannot be a paradox.

But that IS the paradox. QM is a universal theory, it should be valid in all physical systems. The question is, why does it not work inside black holes? The answer is because black holes are lots and lots of gravity, and our understanding of gravity is based on GR, not QM. We do not currently have a working theory of quantum gravity. GR and QM are fundamentally incompatible. We notice it at black holes because there is a big concentration of gravity there, but like QM, GR is a universal theory. There is QM and GR everywhere, “describing” (with astonishing mathematical accuracy in both cases) how the universe works, but they are incompatible with each other. One of the ways they are incompatible is that QM says information can not be destroyed, whilst GR destroys information any time gravity is concentrated in a black-hole-ish-like way. This is the paradox. Two universally applicable robust theories that are incompatible with one another in regards to the conclusions drawn about the permanence of information.

Why do you think QM should not be valid inside a black hole? You called it a silly idea earlier. What’s silly about the idea that QM should work inside black holes? Separately from the fact that GR says it does not work, I mean.

The silly part is assuming it will work.

IF it turned out that everything worked just fine inside a black hole, and if there was a reasonable level of observational to back that up, then it would be quite reasonable to take that as evidence that QM did work inside black holes, but then there wouldn’t be a paradox.

But if it turns out that the maths of QM doesn’t work inside black holes, then it seems reasonable to assume that QM doesn’t apply inside black holes, and there is still no paradox.

A bit late to ask that now.

It was a perfectly valid question 30 years ago. Perhaps even 20 years ago.

mollwollfumble said:

A bit late to ask that now.

It was a perfectly valid question 30 years ago. Perhaps even 20 years ago.

Well according to the Internet:
The first picture of a black hole was taken in 2019 by the Event Horizon Telescope (EHT), a global network of telescopes123. The black hole is at the center of the galaxy M87, which is 55 million light-years away from Earth1234. The picture shows a bright ring with a dark, central spot12345. The ring is a disk of gas orbiting the black hole, and the spot is the black hole’s shadow12345. The picture also revealed polarized light around the black hole2. The picture is the first direct visual evidence that black holes exist

and my quote from Richard Muller was from 2018, so maybe he has changed his mind now.

but:

Is it possible that the pictures are not actually black holes?

What was the evidence 19 years ago that questioning the existence of black holes was not reasonable?

The Rev Dodgson said:

mollwollfumble said:

A bit late to ask that now.

It was a perfectly valid question 30 years ago. Perhaps even 20 years ago.

Well according to the Internet:
The first picture of a black hole was taken in 2019 by the Event Horizon Telescope (EHT), a global network of telescopes123. The black hole is at the center of the galaxy M87, which is 55 million light-years away from Earth1234. The picture shows a bright ring with a dark, central spot12345. The ring is a disk of gas orbiting the black hole, and the spot is the black hole’s shadow12345. The picture also revealed polarized light around the black hole2. The picture is the first direct visual evidence that black holes exist

and my quote from Richard Muller was from 2018, so maybe he has changed his mind now.

but:

Is it possible that the pictures are not actually black holes?

What was the evidence 19 years ago that questioning the existence of black holes was not reasonable?

The images are not really that significant. They’re just in keeping with what was already known from less photogenic observations of what’s going on in regard to gravity, mass and volume in those dense regions.

The empirical evidence confirms that black holes, defined as dense objects that have undergone gravitational collapse to within their own Schwarzschild radius, do exist.

But modelling such objects in detail remains a challenge for theoretical physics (and is apparently beyond the capacity of observational physics).

Bubblecar said:

The Rev Dodgson said:

mollwollfumble said:

A bit late to ask that now.

It was a perfectly valid question 30 years ago. Perhaps even 20 years ago.

Well according to the Internet:
The first picture of a black hole was taken in 2019 by the Event Horizon Telescope (EHT), a global network of telescopes123. The black hole is at the center of the galaxy M87, which is 55 million light-years away from Earth1234. The picture shows a bright ring with a dark, central spot12345. The ring is a disk of gas orbiting the black hole, and the spot is the black hole’s shadow12345. The picture also revealed polarized light around the black hole2. The picture is the first direct visual evidence that black holes exist

and my quote from Richard Muller was from 2018, so maybe he has changed his mind now.

but:

Is it possible that the pictures are not actually black holes?

What was the evidence 19 years ago that questioning the existence of black holes was not reasonable?

The images are not really that significant. They’re just in keeping with what was already known from less photogenic observations of what’s going on in regard to gravity, mass and volume in those dense regions.

The empirical evidence confirms that black holes, defined as dense objects that have undergone gravitational collapse to within their own Schwarzschild radius, do exist.

But modelling such objects in detail remains a challenge for theoretical physics (and is apparently beyond the capacity of observational physics).

All good points but from my reading it appears the Mersini-Houghton modelling produced results that would, if valid, would preclude even such collapses to the point of a SR because the loss of mass would be too fast. That paper is nearly a decade old so it would be interesting to ask what she reckons about more recent results.

Maybe I should read this paper and all, by the same author

https://www.dailystar.co.uk/news/weird-news/scientist-has-seen-universe-next-28454965

Leading cosmologist Laura Mersini-Houghton has observed physical evidence of other universes – and explains to the Daily Star why some of them could be more hospitable to life than ours

While parallel universes might seem like something dreamed up by Marvel Comics writers, scientists say that not only are other universes likely, but they’ve actually seen evidence of them in the night sky.

Leading cosmologist Laura Mersini-Houghton says that fingerprints of these alternate universes can be identified in the cosmic background radiation at the very edges of the visible universe.

She explains that while different physical constants might prevail in another cosmos, changing the laws of physics by even quite large factors still makes those realities habitable.
“Our universe seems to be only borderline habitable,” she says. “We were sitting right at the edge between habitable and non-habitable.”

dv said:

Maybe I should read this paper and all, by the same author

https://www.dailystar.co.uk/news/weird-news/scientist-has-seen-universe-next-28454965

Leading cosmologist Laura Mersini-Houghton has observed physical evidence of other universes – and explains to the Daily Star why some of them could be more hospitable to life than ours

While parallel universes might seem like something dreamed up by Marvel Comics writers, scientists say that not only are other universes likely, but they’ve actually seen evidence of them in the night sky.

Leading cosmologist Laura Mersini-Houghton says that fingerprints of these alternate universes can be identified in the cosmic background radiation at the very edges of the visible universe.

She explains that while different physical constants might prevail in another cosmos, changing the laws of physics by even quite large factors still makes those realities habitable.
“Our universe seems to be only borderline habitable,” she says. “We were sitting right at the edge between habitable and non-habitable.”

Yes, she has some interesting ideas.

I think they’re real but then I still believe in faeries so….

Bubblecar said:

The Rev Dodgson said:

mollwollfumble said:

A bit late to ask that now.

It was a perfectly valid question 30 years ago. Perhaps even 20 years ago.

Well according to the Internet:
The first picture of a black hole was taken in 2019 by the Event Horizon Telescope (EHT), a global network of telescopes123. The black hole is at the center of the galaxy M87, which is 55 million light-years away from Earth1234. The picture shows a bright ring with a dark, central spot12345. The ring is a disk of gas orbiting the black hole, and the spot is the black hole’s shadow12345. The picture also revealed polarized light around the black hole2. The picture is the first direct visual evidence that black holes exist

and my quote from Richard Muller was from 2018, so maybe he has changed his mind now.

but:

Is it possible that the pictures are not actually black holes?

What was the evidence 19 years ago that questioning the existence of black holes was not reasonable?

The images are not really that significant. They’re just in keeping with what was already known from less photogenic observations of what’s going on in regard to gravity, mass and volume in those dense regions.

The empirical evidence confirms that black holes, defined as dense objects that have undergone gravitational collapse to within their own Schwarzschild radius, do exist.

But modelling such objects in detail remains a challenge for theoretical physics (and is apparently beyond the capacity of observational physics).

I see dv has already said what i would have said (but he said it more clearly), so I’ll just say that until today I had no idea that some reputable physicists think (thought?) that black holes might not exist.

The Rev Dodgson said:

esselte said:

The Rev Dodgson said:

So the question is, when does a lack of knowledge become a paradox.

I’d say it does when we have good reason to think that all the statements leading to the paradox are valid.

So any statement based on QM (as we understand it) being valid inside a black hole cannot be a paradox.

But that IS the paradox. QM is a universal theory, it should be valid in all physical systems. The question is, why does it not work inside black holes? The answer is because black holes are lots and lots of gravity, and our understanding of gravity is based on GR, not QM. We do not currently have a working theory of quantum gravity. GR and QM are fundamentally incompatible. We notice it at black holes because there is a big concentration of gravity there, but like QM, GR is a universal theory. There is QM and GR everywhere, “describing” (with astonishing mathematical accuracy in both cases) how the universe works, but they are incompatible with each other. One of the ways they are incompatible is that QM says information can not be destroyed, whilst GR destroys information any time gravity is concentrated in a black-hole-ish-like way. This is the paradox. Two universally applicable robust theories that are incompatible with one another in regards to the conclusions drawn about the permanence of information.

Why do you think QM should not be valid inside a black hole? You called it a silly idea earlier. What’s silly about the idea that QM should work inside black holes? Separately from the fact that GR says it does not work, I mean.

The silly part is assuming it will work.

IF it turned out that everything worked just fine inside a black hole, and if there was a reasonable level of observational to back that up, then it would be quite reasonable to take that as evidence that QM did work inside black holes, but then there wouldn’t be a paradox.

But if it turns out that the maths of QM doesn’t work inside black holes, then it seems reasonable to assume that QM doesn’t apply inside black holes, and there is still no paradox.

QM and GR are not only incompatible at black holes though. In the absence of a Grand Unified Theory they are incompatible, or at least can not be reconciled, throughout the entire universe. We just don’t notice the incompatibility so much in our maths because the two theories are working in different domains (macroscopic and microscopic), except at black holes because of all the gravity there pulling in information and destroying it in ways that it shouldn’t which forces us to try to reconcile the two theories. Information is lost as soon as it crosses the event horizon, but the laws of physics of the whole universe don’t stop being applicable just because we are inside the event horizon of a black hole, except at the singularity. Is it reasonable to assume QM doesn’t apply in the rest of the non-singularity-like universe because it is incompatible with GR?

esselte said:

The Rev Dodgson said:

esselte said:

But that IS the paradox. QM is a universal theory, it should be valid in all physical systems. The question is, why does it not work inside black holes? The answer is because black holes are lots and lots of gravity, and our understanding of gravity is based on GR, not QM. We do not currently have a working theory of quantum gravity. GR and QM are fundamentally incompatible. We notice it at black holes because there is a big concentration of gravity there, but like QM, GR is a universal theory. There is QM and GR everywhere, “describing” (with astonishing mathematical accuracy in both cases) how the universe works, but they are incompatible with each other. One of the ways they are incompatible is that QM says information can not be destroyed, whilst GR destroys information any time gravity is concentrated in a black-hole-ish-like way. This is the paradox. Two universally applicable robust theories that are incompatible with one another in regards to the conclusions drawn about the permanence of information.

Why do you think QM should not be valid inside a black hole? You called it a silly idea earlier. What’s silly about the idea that QM should work inside black holes? Separately from the fact that GR says it does not work, I mean.

The silly part is assuming it will work.

IF it turned out that everything worked just fine inside a black hole, and if there was a reasonable level of observational to back that up, then it would be quite reasonable to take that as evidence that QM did work inside black holes, but then there wouldn’t be a paradox.

But if it turns out that the maths of QM doesn’t work inside black holes, then it seems reasonable to assume that QM doesn’t apply inside black holes, and there is still no paradox.

QM and GR are not only incompatible at black holes though. In the absence of a Grand Unified Theory they are incompatible, or at least can not be reconciled, throughout the entire universe. We just don’t notice the incompatibility so much in our maths because the two theories are working in different domains (macroscopic and microscopic), except at black holes because of all the gravity there pulling in information and destroying it in ways that it shouldn’t which forces us to try to reconcile the two theories. Information is lost as soon as it crosses the event horizon, but the laws of physics of the whole universe don’t stop being applicable just because we are inside the event horizon of a black hole, except at the singularity. Is it reasonable to assume QM doesn’t apply in the rest of the non-singularity-like universe because it is incompatible with GR?

For the Universe outside black holes, at least the tiny little bit of it we can observe, I didn’t suggest that QM doesn’t apply.

For the Universe inside black holes, there is no reason to assume that QM works the same there, and even if it does, interactions between inside and outside have to pass through a zone where it doesn’t.

The Rev Dodgson said:

Black holes resolve paradoxes by destroying quantum states

Black holes resolve paradoxes by destroying quantum states said:

A quantum experiment near a black hole creates a paradox
First the team imagined a person, call her Alice, performing the famous double-slit experiment in a lab orbiting a black hole (SN: 11/5/10). In this classic example of quantum physics, a scientist sends a particle, like an electron or a photon, toward a pair of slits in a solid barrier. If no one observes the particle’s progress, an interference pattern typical of waves appears on a screen on the other side of the barrier, as if the particle went through both slits at once (SN: 5/3/19). But if someone, or some device, measures the particle’s path, it will register as having gone through one slit or the other. The particle’s quantum state of apparently being in two places at once collapses.

Then the team imagined another person, Bob, sitting just inside a black hole’s event horizon — the boundary beyond which not even light can escape the black hole’s gravity. Even though Bob is doomed, he can still make measurements (SN: 5/16/14). The laws of physics behave the same just inside the horizon as outside. “At the horizon, you wouldn’t even know you fell in,” Satishchandran says.

When Bob observes which slit Alice’s particle went through, the particle’s quantum state will collapse. That would also let Alice know Bob is there, messing up her experiment. But that’s a paradox — nothing done inside a black hole should affect the outside. By the laws of physics, Bob should not be able to communicate with Alice at all.

One problem with this is that quantum entanglement can’t be used to communicate information. If it could, then not only could one communicate from inside a black hole, but also faster than the speed of light, and even backwards in time. Contrary to popular belief, no measurements performed on one half of a population of entangled pairs of particles can determine whether or not the corresponding other half of the population are being measured, and it isn’t until the results of the measurements of both halves are brought together that any correlation can be observed. This is the no-communication theorem.

The Rev Dodgson said:

And something from a few days ago:

Black holes resolve paradoxes by destroying quantum states

I never got why this destroying information thing was supposed to be a paradox anyway.

Surely the assumption that information can’t be destroyed is just an assumption?

I thought the black hole information paradox issue had already been settled with Stephen Hawking conceding his bet with John Preskill.