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Are black holes indistinguishable?
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In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguishable.
Are two black holes, in the same sense, indistinguishable given they have same mass, momentum, etc?
black-holes identical-particles
edited 23 mins ago
ouflak
103114
asked 18 hours ago
Marco
936
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up vote
17
down vote
favorite
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguishable.
Are two black holes, in the same sense, indistinguishable given they have same mass, momentum, etc?
black-holes identical-particles
edited 23 mins ago
ouflak
103114
asked 18 hours ago
Marco
936
7
Location, location, location ! On a macroscopic scale (i.e. away from quantum level effects) location distinguishes two black holes. You can't generally say that about e.g. electrons in an atom.
– StephenG
18 hours ago
Perfect! But i meant the nature of matter and the resulting geometry of black hole
– Marco
18 hours ago
1
@StephenG, what do you mean? (The answer was fun but maybe leaves many people in the dark? : )
– Helen
17 hours ago
Re "if they have the same mass", is this even possible? While charge is quantized, I don't think mass would be, given the mass-energy equivalence and the fact that particles that accrete to a black hole can have any energy.
– jamesqf
7 hours ago
add a comment |Â
up vote
17
down vote
favorite
up vote
17
down vote
favorite
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguishable.
Are two black holes, in the same sense, indistinguishable given they have same mass, momentum, etc?
black-holes identical-particles
edited 23 mins ago
ouflak
103114
asked 18 hours ago
Marco
936
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguishable.
Are two black holes, in the same sense, indistinguishable given they have same mass, momentum, etc?
black-holes identical-particles
black-holes identical-particles
edited 23 mins ago
ouflak
103114
asked 18 hours ago
Marco
936
edited 23 mins ago
ouflak
103114
asked 18 hours ago
Marco
936
edited 23 mins ago
ouflak
103114
edited 23 mins ago
ouflak
103114
edited 23 mins ago
ouflak
103114
103114
asked 18 hours ago
Marco
936
asked 18 hours ago
Marco
936
asked 18 hours ago
Marco
936
936
7
Location, location, location ! On a macroscopic scale (i.e. away from quantum level effects) location distinguishes two black holes. You can't generally say that about e.g. electrons in an atom.
– StephenG
18 hours ago
Perfect! But i meant the nature of matter and the resulting geometry of black hole
– Marco
18 hours ago
1
@StephenG, what do you mean? (The answer was fun but maybe leaves many people in the dark? : )
– Helen
17 hours ago
Re "if they have the same mass", is this even possible? While charge is quantized, I don't think mass would be, given the mass-energy equivalence and the fact that particles that accrete to a black hole can have any energy.
– jamesqf
7 hours ago
add a comment |Â
7
Location, location, location ! On a macroscopic scale (i.e. away from quantum level effects) location distinguishes two black holes. You can't generally say that about e.g. electrons in an atom.
– StephenG
18 hours ago
Perfect! But i meant the nature of matter and the resulting geometry of black hole
– Marco
18 hours ago
1
@StephenG, what do you mean? (The answer was fun but maybe leaves many people in the dark? : )
– Helen
17 hours ago
Re "if they have the same mass", is this even possible? While charge is quantized, I don't think mass would be, given the mass-energy equivalence and the fact that particles that accrete to a black hole can have any energy.
– jamesqf
7 hours ago
7
7
Location, location, location ! On a macroscopic scale (i.e. away from quantum level effects) location distinguishes two black holes. You can't generally say that about e.g. electrons in an atom.
– StephenG
18 hours ago
Location, location, location ! On a macroscopic scale (i.e. away from quantum level effects) location distinguishes two black holes. You can't generally say that about e.g. electrons in an atom.
– StephenG
18 hours ago
Perfect! But i meant the nature of matter and the resulting geometry of black hole
– Marco
18 hours ago
Perfect! But i meant the nature of matter and the resulting geometry of black hole
– Marco
18 hours ago
1
1
@StephenG, what do you mean? (The answer was fun but maybe leaves many people in the dark? : )
– Helen
17 hours ago
@StephenG, what do you mean? (The answer was fun but maybe leaves many people in the dark? : )
– Helen
17 hours ago
Re "if they have the same mass", is this even possible? While charge is quantized, I don't think mass would be, given the mass-energy equivalence and the fact that particles that accrete to a black hole can have any energy.
– jamesqf
7 hours ago
Re "if they have the same mass", is this even possible? While charge is quantized, I don't think mass would be, given the mass-energy equivalence and the fact that particles that accrete to a black hole can have any energy.
– jamesqf
7 hours ago
add a comment |Â
4 Answers
4
active
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up vote
18
down vote
The answer to this question is not technically known. The theorem that applies to this question is the "No-Hair Theorem" which states that a black hole is described by only 3 externally observable properties - mass, charge, and angular momentum - and that's it. The No Hair Theorem implies then that two black holes which have the same mass, charge, and angular momentum are identical to each other no matter the actual matter that was used to create them. E.g. if you create one black hole using a bunch of atoms vs you create another black hole using neutrinos only - the no hair theorem says as long as the two black holes end up with the same mass, charge, and angular momentum, one could not tell the two apart. One could not say which one was the one created by neutrinos and which one was the one created by ordinary atomic matter.
The problem though is that the No Hair theorem is not technically a theorem in that it hasn't been proven yet. It's more of a conjecture or hypothesis at this point. There are motivating factors which seem to imply the No Hair Theorem is true, but alas there is no clear proof using GR that it is.
answered 18 hours ago
enumaris
2,5031318
3
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
1
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
2
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
3
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
1
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
 |Â
show 1 more comment
up vote
11
down vote
To expand on the answer of enumaris, there are four types of black holes based on their mass, charge, and angular momentum. Uncharged non-rotating black holes are called Schwarzschild black holes. These can be different only y mass. Rotating uncharged black holes are called Kerr black holes. Charged non-rotating black holes are called Reissner–Nordstrom black holes. And finally rotating charged black holes are called Kerr–Newman black holes. Physics of different types of black holes is quite different. While all of them contain a singularity, they may have a different number of event horizons of different types and shapes. For example, a charged black hole has a Cauchy horizon inside the Schwarzschild horizon.
The No-Hair conjecture was proven for the Schwarzschild black holes for the simplified case of the uniqueness in 1967. The result since has been expanded to charged and rotating black holes. The general uncharged case has been partially resolved under the additional hypothesis of non-degenerate event horizons and the assumption of real analyticity of the space-time continuum. However there still is no rigorous proof of the general case.
answered 17 hours ago
safesphere
6,67111239
2
Sources, please?
– N. Steinle
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
2
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
 |Â
show 2 more comments
up vote
3
down vote
I'm going to take a different approach to this :
Macroscopic vs. Quantum worlds.
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguable.
Let's remember that an elementary particle is, by definition, identified by these characteristics. The (rest) mass is a fixed value. The spin is fixed, the various charge values are fixed. If they deviate from specific values then you do not have one of these particles at all.
But we say that two e.g. electrons are indistinguishable because in any system we cannot label them and track them in any way. We can make a measurement that says there is an electron at position one and two, but the instant we make those measurements we (in general) cease to know anything about the actual positions of the electrons.
We can't say that when we next measure those electron positions which electron is which - we can't track them. The electron at position one could be at position three or four next, and the electron that was at position two could now be at position three or four. We just know the next measurements produce two distinct measurements for positions of electrons.
Are in the same sense two black holes indistinguable given they have same mass, momentum, etc?
So not in the same sense as elementary particles.
If I have two black holes they have a macroscopic position. Unlike my electrons I can track them easily and there is no mystery between measurements as to which is which. Regardless of the no hair theorem, regardless of their size, rotation, charge, etc. they have distinct locations which can be tracked.
So the black hole that started at position one, I can say with essentially perfect confidence is the same one I measured at position three later. Likewise there's no confusion about whether the other black hole could be at position three and the one I thought was there is actually at position four.
So for macroscopic objects location is a property that labels them uniquely.
But for elementary particles this is not generally the case.
The No Hair Theorem
I think I should point out that the No Hair Theorem does not say we cannot distinguish black holes from each other, even if they are identical in external characteristics. It says that the only information we can determine about the black hole's interior (on the other side of that event horizon) are these "statistical" values.
answered 15 hours ago
StephenG
4,98021323
3
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
add a comment |Â
up vote
2
down vote
Always be careful when your question involves gravity and quantum physics together. We have only very partial knowledge of that combination. In particular, note that the No Hair Theorem is a statement within classical general relativity, and as soon as you bring in quantum physics then things are complicated by the black hole entropy. As I understand it, this entropy is sufficiently well established that we would be very surprised if it turned out to be not there, and the place where it is found is on the horizon, and it typically has a large value. In this sense, black holes have a lot of "hair", i.e. physical properties that can distinguish one of them from another. The entropy is often huge: they have a huge amount of "hair", in the sense of available microstates consistent with their macrostate.
answered 14 hours ago
Andrew Steane
662
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
18
down vote
The answer to this question is not technically known. The theorem that applies to this question is the "No-Hair Theorem" which states that a black hole is described by only 3 externally observable properties - mass, charge, and angular momentum - and that's it. The No Hair Theorem implies then that two black holes which have the same mass, charge, and angular momentum are identical to each other no matter the actual matter that was used to create them. E.g. if you create one black hole using a bunch of atoms vs you create another black hole using neutrinos only - the no hair theorem says as long as the two black holes end up with the same mass, charge, and angular momentum, one could not tell the two apart. One could not say which one was the one created by neutrinos and which one was the one created by ordinary atomic matter.
The problem though is that the No Hair theorem is not technically a theorem in that it hasn't been proven yet. It's more of a conjecture or hypothesis at this point. There are motivating factors which seem to imply the No Hair Theorem is true, but alas there is no clear proof using GR that it is.
answered 18 hours ago
enumaris
2,5031318
3
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
1
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
2
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
3
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
1
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
 |Â
show 1 more comment
up vote
18
down vote
The answer to this question is not technically known. The theorem that applies to this question is the "No-Hair Theorem" which states that a black hole is described by only 3 externally observable properties - mass, charge, and angular momentum - and that's it. The No Hair Theorem implies then that two black holes which have the same mass, charge, and angular momentum are identical to each other no matter the actual matter that was used to create them. E.g. if you create one black hole using a bunch of atoms vs you create another black hole using neutrinos only - the no hair theorem says as long as the two black holes end up with the same mass, charge, and angular momentum, one could not tell the two apart. One could not say which one was the one created by neutrinos and which one was the one created by ordinary atomic matter.
The problem though is that the No Hair theorem is not technically a theorem in that it hasn't been proven yet. It's more of a conjecture or hypothesis at this point. There are motivating factors which seem to imply the No Hair Theorem is true, but alas there is no clear proof using GR that it is.
answered 18 hours ago
enumaris
2,5031318
3
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
1
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
2
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
3
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
1
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
 |Â
show 1 more comment
up vote
18
down vote
up vote
18
down vote
The answer to this question is not technically known. The theorem that applies to this question is the "No-Hair Theorem" which states that a black hole is described by only 3 externally observable properties - mass, charge, and angular momentum - and that's it. The No Hair Theorem implies then that two black holes which have the same mass, charge, and angular momentum are identical to each other no matter the actual matter that was used to create them. E.g. if you create one black hole using a bunch of atoms vs you create another black hole using neutrinos only - the no hair theorem says as long as the two black holes end up with the same mass, charge, and angular momentum, one could not tell the two apart. One could not say which one was the one created by neutrinos and which one was the one created by ordinary atomic matter.
The problem though is that the No Hair theorem is not technically a theorem in that it hasn't been proven yet. It's more of a conjecture or hypothesis at this point. There are motivating factors which seem to imply the No Hair Theorem is true, but alas there is no clear proof using GR that it is.
answered 18 hours ago
enumaris
2,5031318
The answer to this question is not technically known. The theorem that applies to this question is the "No-Hair Theorem" which states that a black hole is described by only 3 externally observable properties - mass, charge, and angular momentum - and that's it. The No Hair Theorem implies then that two black holes which have the same mass, charge, and angular momentum are identical to each other no matter the actual matter that was used to create them. E.g. if you create one black hole using a bunch of atoms vs you create another black hole using neutrinos only - the no hair theorem says as long as the two black holes end up with the same mass, charge, and angular momentum, one could not tell the two apart. One could not say which one was the one created by neutrinos and which one was the one created by ordinary atomic matter.
The problem though is that the No Hair theorem is not technically a theorem in that it hasn't been proven yet. It's more of a conjecture or hypothesis at this point. There are motivating factors which seem to imply the No Hair Theorem is true, but alas there is no clear proof using GR that it is.
answered 18 hours ago
enumaris
2,5031318
answered 18 hours ago
enumaris
2,5031318
answered 18 hours ago
enumaris
2,5031318
answered 18 hours ago
enumaris
2,5031318
2,5031318
3
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
1
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
2
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
3
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
1
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
 |Â
show 1 more comment
3
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
1
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
2
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
3
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
1
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
3
3
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
There are also some special cases in which it fails: en.wikipedia.org/wiki/No-hair_theorem#Counterexamples
– J.G.
18 hours ago
1
1
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
There is a more serious problem though. The No Hair Theorem applies to the exact solution of a rotating, charged black hole. In practice, black holes are often surrounded by matter in the form of accretion disks, and that exact solution is only an approximation.
– Andrea
14 hours ago
2
2
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
No-hair theorem also wrecks chaos in quantum mechanics in the form of the information paradox.
– John Dvorak
14 hours ago
3
3
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
Is there any proven theorem in Physics? I thought all we had were "good enough" models.
– Eric Duminil
5 hours ago
1
1
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
@EricDuminil You can certainly prove theorems within a particular model, because that's just mathematics, but you can't prove that the model corresponds to the real world.
– David Richerby
52 mins ago
 |Â
show 1 more comment
up vote
11
down vote
To expand on the answer of enumaris, there are four types of black holes based on their mass, charge, and angular momentum. Uncharged non-rotating black holes are called Schwarzschild black holes. These can be different only y mass. Rotating uncharged black holes are called Kerr black holes. Charged non-rotating black holes are called Reissner–Nordstrom black holes. And finally rotating charged black holes are called Kerr–Newman black holes. Physics of different types of black holes is quite different. While all of them contain a singularity, they may have a different number of event horizons of different types and shapes. For example, a charged black hole has a Cauchy horizon inside the Schwarzschild horizon.
The No-Hair conjecture was proven for the Schwarzschild black holes for the simplified case of the uniqueness in 1967. The result since has been expanded to charged and rotating black holes. The general uncharged case has been partially resolved under the additional hypothesis of non-degenerate event horizons and the assumption of real analyticity of the space-time continuum. However there still is no rigorous proof of the general case.
answered 17 hours ago
safesphere
6,67111239
2
Sources, please?
– N. Steinle
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
2
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
 |Â
show 2 more comments
up vote
11
down vote
To expand on the answer of enumaris, there are four types of black holes based on their mass, charge, and angular momentum. Uncharged non-rotating black holes are called Schwarzschild black holes. These can be different only y mass. Rotating uncharged black holes are called Kerr black holes. Charged non-rotating black holes are called Reissner–Nordstrom black holes. And finally rotating charged black holes are called Kerr–Newman black holes. Physics of different types of black holes is quite different. While all of them contain a singularity, they may have a different number of event horizons of different types and shapes. For example, a charged black hole has a Cauchy horizon inside the Schwarzschild horizon.
The No-Hair conjecture was proven for the Schwarzschild black holes for the simplified case of the uniqueness in 1967. The result since has been expanded to charged and rotating black holes. The general uncharged case has been partially resolved under the additional hypothesis of non-degenerate event horizons and the assumption of real analyticity of the space-time continuum. However there still is no rigorous proof of the general case.
answered 17 hours ago
safesphere
6,67111239
2
Sources, please?
– N. Steinle
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
2
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
 |Â
show 2 more comments
up vote
11
down vote
up vote
11
down vote
To expand on the answer of enumaris, there are four types of black holes based on their mass, charge, and angular momentum. Uncharged non-rotating black holes are called Schwarzschild black holes. These can be different only y mass. Rotating uncharged black holes are called Kerr black holes. Charged non-rotating black holes are called Reissner–Nordstrom black holes. And finally rotating charged black holes are called Kerr–Newman black holes. Physics of different types of black holes is quite different. While all of them contain a singularity, they may have a different number of event horizons of different types and shapes. For example, a charged black hole has a Cauchy horizon inside the Schwarzschild horizon.
The No-Hair conjecture was proven for the Schwarzschild black holes for the simplified case of the uniqueness in 1967. The result since has been expanded to charged and rotating black holes. The general uncharged case has been partially resolved under the additional hypothesis of non-degenerate event horizons and the assumption of real analyticity of the space-time continuum. However there still is no rigorous proof of the general case.
answered 17 hours ago
safesphere
6,67111239
To expand on the answer of enumaris, there are four types of black holes based on their mass, charge, and angular momentum. Uncharged non-rotating black holes are called Schwarzschild black holes. These can be different only y mass. Rotating uncharged black holes are called Kerr black holes. Charged non-rotating black holes are called Reissner–Nordstrom black holes. And finally rotating charged black holes are called Kerr–Newman black holes. Physics of different types of black holes is quite different. While all of them contain a singularity, they may have a different number of event horizons of different types and shapes. For example, a charged black hole has a Cauchy horizon inside the Schwarzschild horizon.
The No-Hair conjecture was proven for the Schwarzschild black holes for the simplified case of the uniqueness in 1967. The result since has been expanded to charged and rotating black holes. The general uncharged case has been partially resolved under the additional hypothesis of non-degenerate event horizons and the assumption of real analyticity of the space-time continuum. However there still is no rigorous proof of the general case.
answered 17 hours ago
safesphere
6,67111239
answered 17 hours ago
safesphere
6,67111239
answered 17 hours ago
safesphere
6,67111239
answered 17 hours ago
safesphere
6,67111239
6,67111239
2
Sources, please?
– N. Steinle
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
2
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
 |Â
show 2 more comments
2
Sources, please?
– N. Steinle
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
2
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
2
2
Sources, please?
– N. Steinle
17 hours ago
Sources, please?
– N. Steinle
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
@N.Steinle The source for the information on the No-Hair theorem is in the link in the answer by enumaris (or here: en.wikipedia.org/wiki/No-hair_theorem). The source for the types of black holes is Wiki: en.wikipedia.org/wiki/Charged_black_hole
– safesphere
17 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
Doesn't seem like mass factors into the "type" of black hole, although it's certainly a distinguishing factor. There are two choices for charge (charged or uncharged) and two for rotation (rotating or non-rotating), which makes for 2x2=4 types of blackholes. Meanwhile mass is a continuous variable.
– BallpointBen
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
@BallpointBen Yes indeed. I can't think of any even hypothetical possibility for a any type black hole not to have mass. For example, a collapsing spere of light does have a rest mass even before it forms a black hole despite each photon being massless.
– safesphere
15 hours ago
2
2
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
I think these four types of BH are just the four mathematical possibilities. In the real world, matter is entering the BH at random off-axis vectors so it will acquire angular momentum in the same way as every other star, planet, moon, and heavenly body. Therefore, all BHs will be rotating. As for charge; this is more likely to be zero, averaged over time (just like stars, planets, moons, etc.). Interestingly, if you ever wanted to move a BH, you could get a handle on it by charging it up (e.g., with an electron beam) and then moving it around with an electric field.
– Oscar Bravo
5 hours ago
 |Â
show 2 more comments
up vote
3
down vote
I'm going to take a different approach to this :
Macroscopic vs. Quantum worlds.
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguable.
Let's remember that an elementary particle is, by definition, identified by these characteristics. The (rest) mass is a fixed value. The spin is fixed, the various charge values are fixed. If they deviate from specific values then you do not have one of these particles at all.
But we say that two e.g. electrons are indistinguishable because in any system we cannot label them and track them in any way. We can make a measurement that says there is an electron at position one and two, but the instant we make those measurements we (in general) cease to know anything about the actual positions of the electrons.
We can't say that when we next measure those electron positions which electron is which - we can't track them. The electron at position one could be at position three or four next, and the electron that was at position two could now be at position three or four. We just know the next measurements produce two distinct measurements for positions of electrons.
Are in the same sense two black holes indistinguable given they have same mass, momentum, etc?
So not in the same sense as elementary particles.
If I have two black holes they have a macroscopic position. Unlike my electrons I can track them easily and there is no mystery between measurements as to which is which. Regardless of the no hair theorem, regardless of their size, rotation, charge, etc. they have distinct locations which can be tracked.
So the black hole that started at position one, I can say with essentially perfect confidence is the same one I measured at position three later. Likewise there's no confusion about whether the other black hole could be at position three and the one I thought was there is actually at position four.
So for macroscopic objects location is a property that labels them uniquely.
But for elementary particles this is not generally the case.
The No Hair Theorem
I think I should point out that the No Hair Theorem does not say we cannot distinguish black holes from each other, even if they are identical in external characteristics. It says that the only information we can determine about the black hole's interior (on the other side of that event horizon) are these "statistical" values.
answered 15 hours ago
StephenG
4,98021323
3
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
add a comment |Â
up vote
3
down vote
I'm going to take a different approach to this :
Macroscopic vs. Quantum worlds.
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguable.
Let's remember that an elementary particle is, by definition, identified by these characteristics. The (rest) mass is a fixed value. The spin is fixed, the various charge values are fixed. If they deviate from specific values then you do not have one of these particles at all.
But we say that two e.g. electrons are indistinguishable because in any system we cannot label them and track them in any way. We can make a measurement that says there is an electron at position one and two, but the instant we make those measurements we (in general) cease to know anything about the actual positions of the electrons.
We can't say that when we next measure those electron positions which electron is which - we can't track them. The electron at position one could be at position three or four next, and the electron that was at position two could now be at position three or four. We just know the next measurements produce two distinct measurements for positions of electrons.
Are in the same sense two black holes indistinguable given they have same mass, momentum, etc?
So not in the same sense as elementary particles.
If I have two black holes they have a macroscopic position. Unlike my electrons I can track them easily and there is no mystery between measurements as to which is which. Regardless of the no hair theorem, regardless of their size, rotation, charge, etc. they have distinct locations which can be tracked.
So the black hole that started at position one, I can say with essentially perfect confidence is the same one I measured at position three later. Likewise there's no confusion about whether the other black hole could be at position three and the one I thought was there is actually at position four.
So for macroscopic objects location is a property that labels them uniquely.
But for elementary particles this is not generally the case.
The No Hair Theorem
I think I should point out that the No Hair Theorem does not say we cannot distinguish black holes from each other, even if they are identical in external characteristics. It says that the only information we can determine about the black hole's interior (on the other side of that event horizon) are these "statistical" values.
answered 15 hours ago
StephenG
4,98021323
3
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
add a comment |Â
up vote
3
down vote
up vote
3
down vote
I'm going to take a different approach to this :
Macroscopic vs. Quantum worlds.
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguable.
Let's remember that an elementary particle is, by definition, identified by these characteristics. The (rest) mass is a fixed value. The spin is fixed, the various charge values are fixed. If they deviate from specific values then you do not have one of these particles at all.
But we say that two e.g. electrons are indistinguishable because in any system we cannot label them and track them in any way. We can make a measurement that says there is an electron at position one and two, but the instant we make those measurements we (in general) cease to know anything about the actual positions of the electrons.
We can't say that when we next measure those electron positions which electron is which - we can't track them. The electron at position one could be at position three or four next, and the electron that was at position two could now be at position three or four. We just know the next measurements produce two distinct measurements for positions of electrons.
Are in the same sense two black holes indistinguable given they have same mass, momentum, etc?
So not in the same sense as elementary particles.
If I have two black holes they have a macroscopic position. Unlike my electrons I can track them easily and there is no mystery between measurements as to which is which. Regardless of the no hair theorem, regardless of their size, rotation, charge, etc. they have distinct locations which can be tracked.
So the black hole that started at position one, I can say with essentially perfect confidence is the same one I measured at position three later. Likewise there's no confusion about whether the other black hole could be at position three and the one I thought was there is actually at position four.
So for macroscopic objects location is a property that labels them uniquely.
But for elementary particles this is not generally the case.
The No Hair Theorem
I think I should point out that the No Hair Theorem does not say we cannot distinguish black holes from each other, even if they are identical in external characteristics. It says that the only information we can determine about the black hole's interior (on the other side of that event horizon) are these "statistical" values.
answered 15 hours ago
StephenG
4,98021323
I'm going to take a different approach to this :
Macroscopic vs. Quantum worlds.
In standard model of particles it is understood that besides characteristics like momentum, spin, etc two electrons are indistinguable.
Let's remember that an elementary particle is, by definition, identified by these characteristics. The (rest) mass is a fixed value. The spin is fixed, the various charge values are fixed. If they deviate from specific values then you do not have one of these particles at all.
But we say that two e.g. electrons are indistinguishable because in any system we cannot label them and track them in any way. We can make a measurement that says there is an electron at position one and two, but the instant we make those measurements we (in general) cease to know anything about the actual positions of the electrons.
We can't say that when we next measure those electron positions which electron is which - we can't track them. The electron at position one could be at position three or four next, and the electron that was at position two could now be at position three or four. We just know the next measurements produce two distinct measurements for positions of electrons.
Are in the same sense two black holes indistinguable given they have same mass, momentum, etc?
So not in the same sense as elementary particles.
If I have two black holes they have a macroscopic position. Unlike my electrons I can track them easily and there is no mystery between measurements as to which is which. Regardless of the no hair theorem, regardless of their size, rotation, charge, etc. they have distinct locations which can be tracked.
So the black hole that started at position one, I can say with essentially perfect confidence is the same one I measured at position three later. Likewise there's no confusion about whether the other black hole could be at position three and the one I thought was there is actually at position four.
So for macroscopic objects location is a property that labels them uniquely.
But for elementary particles this is not generally the case.
The No Hair Theorem
I think I should point out that the No Hair Theorem does not say we cannot distinguish black holes from each other, even if they are identical in external characteristics. It says that the only information we can determine about the black hole's interior (on the other side of that event horizon) are these "statistical" values.
answered 15 hours ago
StephenG
4,98021323
answered 15 hours ago
StephenG
4,98021323
answered 15 hours ago
StephenG
4,98021323
answered 15 hours ago
StephenG
4,98021323
4,98021323
3
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
add a comment |Â
3
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
3
3
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
The critical distinction you bring is the ability to track. This ability is indeed different in the quantum and classical cases, but it has more to do with the environment than with the objects themselves. You can put two electrons in two chambers isolated enough to make tunneling improbable (like tunnelling of two black holes into each other). Then you can track each electron separately. On the other hand, two black holes of the same parameters (e.g. spinning around each other) are different only by your prior knowledge. If you lose your records, you would not be able to tell them apart.
– safesphere
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
If you are allowed to consider the location to be a distinguishing characteristic, why not the accretion disks also? Those must certainly have significant differences.
– D. Halsey
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
You can also say with absolute confidence that the electrons at A and B are different if A and B are space-like separated
– John Dvorak
14 hours ago
add a comment |Â
up vote
2
down vote
Always be careful when your question involves gravity and quantum physics together. We have only very partial knowledge of that combination. In particular, note that the No Hair Theorem is a statement within classical general relativity, and as soon as you bring in quantum physics then things are complicated by the black hole entropy. As I understand it, this entropy is sufficiently well established that we would be very surprised if it turned out to be not there, and the place where it is found is on the horizon, and it typically has a large value. In this sense, black holes have a lot of "hair", i.e. physical properties that can distinguish one of them from another. The entropy is often huge: they have a huge amount of "hair", in the sense of available microstates consistent with their macrostate.
answered 14 hours ago
Andrew Steane
662
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
2
down vote
Always be careful when your question involves gravity and quantum physics together. We have only very partial knowledge of that combination. In particular, note that the No Hair Theorem is a statement within classical general relativity, and as soon as you bring in quantum physics then things are complicated by the black hole entropy. As I understand it, this entropy is sufficiently well established that we would be very surprised if it turned out to be not there, and the place where it is found is on the horizon, and it typically has a large value. In this sense, black holes have a lot of "hair", i.e. physical properties that can distinguish one of them from another. The entropy is often huge: they have a huge amount of "hair", in the sense of available microstates consistent with their macrostate.
answered 14 hours ago
Andrew Steane
662
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Always be careful when your question involves gravity and quantum physics together. We have only very partial knowledge of that combination. In particular, note that the No Hair Theorem is a statement within classical general relativity, and as soon as you bring in quantum physics then things are complicated by the black hole entropy. As I understand it, this entropy is sufficiently well established that we would be very surprised if it turned out to be not there, and the place where it is found is on the horizon, and it typically has a large value. In this sense, black holes have a lot of "hair", i.e. physical properties that can distinguish one of them from another. The entropy is often huge: they have a huge amount of "hair", in the sense of available microstates consistent with their macrostate.
answered 14 hours ago
Andrew Steane
662
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Always be careful when your question involves gravity and quantum physics together. We have only very partial knowledge of that combination. In particular, note that the No Hair Theorem is a statement within classical general relativity, and as soon as you bring in quantum physics then things are complicated by the black hole entropy. As I understand it, this entropy is sufficiently well established that we would be very surprised if it turned out to be not there, and the place where it is found is on the horizon, and it typically has a large value. In this sense, black holes have a lot of "hair", i.e. physical properties that can distinguish one of them from another. The entropy is often huge: they have a huge amount of "hair", in the sense of available microstates consistent with their macrostate.
answered 14 hours ago
Andrew Steane
662
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 14 hours ago
Andrew Steane
662
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 14 hours ago
Andrew Steane
662
answered 14 hours ago
Andrew Steane
662
662
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Andrew Steane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
add a comment |Â
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7
Location, location, location ! On a macroscopic scale (i.e. away from quantum level effects) location distinguishes two black holes. You can't generally say that about e.g. electrons in an atom.
– StephenG
18 hours ago
Perfect! But i meant the nature of matter and the resulting geometry of black hole
– Marco
18 hours ago
1
@StephenG, what do you mean? (The answer was fun but maybe leaves many people in the dark? : )
– Helen
17 hours ago
Re "if they have the same mass", is this even possible? While charge is quantized, I don't think mass would be, given the mass-energy equivalence and the fact that particles that accrete to a black hole can have any energy.
– jamesqf
7 hours ago