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How exactly does Hawking radiation decrease the mass of black holes?
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How exactly does Hawking radiation decrease the mass of black holes?
Unicorn Meta Zoo #1: Why another podcast?
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$begingroup$
From what I understand so far, when one of virtual particles crosses the event horizon and the other does not, they can not annihilate each other. The latter wanders off into the universe (btw. is it still virtual at this point, and what does 'virtual' mean at this point, if so?), while the other gets consumed by the black hole. I don't see how this event contributes to evaporation of the black hole (, since the particles do not originate from the black hole). Shouldn't the consumed particle actually add-up to the black hole mass?
The closest question to mine is Does Hawking radiation in fact bring mass into the universe?, but I don't find the answers satisfactory.
I.e. "the escaped virtual particle is 'boosted' by black hole's gravitational field into becoming a real particle", rather adds to the question then answer it.
black-hole hawking-radiation
asked 5 hours ago
Marko36Marko36
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
From what I understand so far, when one of virtual particles crosses the event horizon and the other does not, they can not annihilate each other. The latter wanders off into the universe (btw. is it still virtual at this point, and what does 'virtual' mean at this point, if so?), while the other gets consumed by the black hole. I don't see how this event contributes to evaporation of the black hole (, since the particles do not originate from the black hole). Shouldn't the consumed particle actually add-up to the black hole mass?
The closest question to mine is Does Hawking radiation in fact bring mass into the universe?, but I don't find the answers satisfactory.
I.e. "the escaped virtual particle is 'boosted' by black hole's gravitational field into becoming a real particle", rather adds to the question then answer it.
black-hole hawking-radiation
asked 5 hours ago
Marko36Marko36
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
1
$begingroup$
Forget about virtual particle pairs, that's more like a metaphor. The thing is, black holes emit radiation, regardless of how they do that. Radiation carries energy, which must come from somewhere, there's no free lunch here. But energy equals mass. It all comes out of the black hole's "bank account" of mass, because that's the only thing nearby.
$endgroup$
– Florin Andrei
5 hours ago
$begingroup$
Ok, thanks @Florin Andrei, but virtual particles are commonly accepted as a real thing, so how (much) are they metaphorical? Why? Also, black hole radiation is explicitly explained by them. Should they be a metaphorical concept, what is this black hole radiation, you mentioned, really? Also assuming that "nothing can escape the black hole, not even EM radiation".
$endgroup$
– Marko36
5 hours ago
$begingroup$
@Marko36 It's not that virtual particles are a metaphor in general (although in a sense they are, all particles, virtual or otherwise are just a way of viewing some aspects of the underlying fields), but they are not really a very good explanation of Hawking Radiation. This, however, doesn't answer your question. I look forward to seeing an answer.
$endgroup$
– Steve Linton
4 hours ago
1
$begingroup$
You might like to check out math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html and physics.stackexchange.com/questions/185110/… and other related questions on Physics about virtual particles.
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
This question on physics (and its accepted answer come the closest I have yet found to addressing this question) but they still don't answer it completely. physics.stackexchange.com/questions/251385/….
$endgroup$
– Steve Linton
15 mins ago
add a comment |
$begingroup$
From what I understand so far, when one of virtual particles crosses the event horizon and the other does not, they can not annihilate each other. The latter wanders off into the universe (btw. is it still virtual at this point, and what does 'virtual' mean at this point, if so?), while the other gets consumed by the black hole. I don't see how this event contributes to evaporation of the black hole (, since the particles do not originate from the black hole). Shouldn't the consumed particle actually add-up to the black hole mass?
The closest question to mine is Does Hawking radiation in fact bring mass into the universe?, but I don't find the answers satisfactory.
I.e. "the escaped virtual particle is 'boosted' by black hole's gravitational field into becoming a real particle", rather adds to the question then answer it.
black-hole hawking-radiation
asked 5 hours ago
Marko36Marko36
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
From what I understand so far, when one of virtual particles crosses the event horizon and the other does not, they can not annihilate each other. The latter wanders off into the universe (btw. is it still virtual at this point, and what does 'virtual' mean at this point, if so?), while the other gets consumed by the black hole. I don't see how this event contributes to evaporation of the black hole (, since the particles do not originate from the black hole). Shouldn't the consumed particle actually add-up to the black hole mass?
The closest question to mine is Does Hawking radiation in fact bring mass into the universe?, but I don't find the answers satisfactory.
I.e. "the escaped virtual particle is 'boosted' by black hole's gravitational field into becoming a real particle", rather adds to the question then answer it.
black-hole hawking-radiation
black-hole hawking-radiation
asked 5 hours ago
Marko36Marko36
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
Marko36Marko36
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
Marko36Marko36
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
Marko36Marko36
463
asked 5 hours ago
Marko36Marko36
463
463
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Marko36 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
$begingroup$
Forget about virtual particle pairs, that's more like a metaphor. The thing is, black holes emit radiation, regardless of how they do that. Radiation carries energy, which must come from somewhere, there's no free lunch here. But energy equals mass. It all comes out of the black hole's "bank account" of mass, because that's the only thing nearby.
$endgroup$
– Florin Andrei
5 hours ago
$begingroup$
Ok, thanks @Florin Andrei, but virtual particles are commonly accepted as a real thing, so how (much) are they metaphorical? Why? Also, black hole radiation is explicitly explained by them. Should they be a metaphorical concept, what is this black hole radiation, you mentioned, really? Also assuming that "nothing can escape the black hole, not even EM radiation".
$endgroup$
– Marko36
5 hours ago
$begingroup$
@Marko36 It's not that virtual particles are a metaphor in general (although in a sense they are, all particles, virtual or otherwise are just a way of viewing some aspects of the underlying fields), but they are not really a very good explanation of Hawking Radiation. This, however, doesn't answer your question. I look forward to seeing an answer.
$endgroup$
– Steve Linton
4 hours ago
1
$begingroup$
You might like to check out math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html and physics.stackexchange.com/questions/185110/… and other related questions on Physics about virtual particles.
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
This question on physics (and its accepted answer come the closest I have yet found to addressing this question) but they still don't answer it completely. physics.stackexchange.com/questions/251385/….
$endgroup$
– Steve Linton
15 mins ago
add a comment |
1
$begingroup$
Forget about virtual particle pairs, that's more like a metaphor. The thing is, black holes emit radiation, regardless of how they do that. Radiation carries energy, which must come from somewhere, there's no free lunch here. But energy equals mass. It all comes out of the black hole's "bank account" of mass, because that's the only thing nearby.
$endgroup$
– Florin Andrei
5 hours ago
$begingroup$
Ok, thanks @Florin Andrei, but virtual particles are commonly accepted as a real thing, so how (much) are they metaphorical? Why? Also, black hole radiation is explicitly explained by them. Should they be a metaphorical concept, what is this black hole radiation, you mentioned, really? Also assuming that "nothing can escape the black hole, not even EM radiation".
$endgroup$
– Marko36
5 hours ago
$begingroup$
@Marko36 It's not that virtual particles are a metaphor in general (although in a sense they are, all particles, virtual or otherwise are just a way of viewing some aspects of the underlying fields), but they are not really a very good explanation of Hawking Radiation. This, however, doesn't answer your question. I look forward to seeing an answer.
$endgroup$
– Steve Linton
4 hours ago
1
$begingroup$
You might like to check out math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html and physics.stackexchange.com/questions/185110/… and other related questions on Physics about virtual particles.
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
This question on physics (and its accepted answer come the closest I have yet found to addressing this question) but they still don't answer it completely. physics.stackexchange.com/questions/251385/….
$endgroup$
– Steve Linton
15 mins ago
1
1
$begingroup$
Forget about virtual particle pairs, that's more like a metaphor. The thing is, black holes emit radiation, regardless of how they do that. Radiation carries energy, which must come from somewhere, there's no free lunch here. But energy equals mass. It all comes out of the black hole's "bank account" of mass, because that's the only thing nearby.
$endgroup$
– Florin Andrei
5 hours ago
$begingroup$
Forget about virtual particle pairs, that's more like a metaphor. The thing is, black holes emit radiation, regardless of how they do that. Radiation carries energy, which must come from somewhere, there's no free lunch here. But energy equals mass. It all comes out of the black hole's "bank account" of mass, because that's the only thing nearby.
$endgroup$
– Florin Andrei
5 hours ago
$begingroup$
Ok, thanks @Florin Andrei, but virtual particles are commonly accepted as a real thing, so how (much) are they metaphorical? Why? Also, black hole radiation is explicitly explained by them. Should they be a metaphorical concept, what is this black hole radiation, you mentioned, really? Also assuming that "nothing can escape the black hole, not even EM radiation".
$endgroup$
– Marko36
5 hours ago
$begingroup$
Ok, thanks @Florin Andrei, but virtual particles are commonly accepted as a real thing, so how (much) are they metaphorical? Why? Also, black hole radiation is explicitly explained by them. Should they be a metaphorical concept, what is this black hole radiation, you mentioned, really? Also assuming that "nothing can escape the black hole, not even EM radiation".
$endgroup$
– Marko36
5 hours ago
$begingroup$
@Marko36 It's not that virtual particles are a metaphor in general (although in a sense they are, all particles, virtual or otherwise are just a way of viewing some aspects of the underlying fields), but they are not really a very good explanation of Hawking Radiation. This, however, doesn't answer your question. I look forward to seeing an answer.
$endgroup$
– Steve Linton
4 hours ago
$begingroup$
@Marko36 It's not that virtual particles are a metaphor in general (although in a sense they are, all particles, virtual or otherwise are just a way of viewing some aspects of the underlying fields), but they are not really a very good explanation of Hawking Radiation. This, however, doesn't answer your question. I look forward to seeing an answer.
$endgroup$
– Steve Linton
4 hours ago
1
1
$begingroup$
You might like to check out math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html and physics.stackexchange.com/questions/185110/… and other related questions on Physics about virtual particles.
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
You might like to check out math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html and physics.stackexchange.com/questions/185110/… and other related questions on Physics about virtual particles.
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
This question on physics (and its accepted answer come the closest I have yet found to addressing this question) but they still don't answer it completely. physics.stackexchange.com/questions/251385/….
$endgroup$
– Steve Linton
15 mins ago
$begingroup$
This question on physics (and its accepted answer come the closest I have yet found to addressing this question) but they still don't answer it completely. physics.stackexchange.com/questions/251385/….
$endgroup$
– Steve Linton
15 mins ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
I'm going to give you an intuitive answer. Keep in mind, this is not the "actual" answer, as the Hawking radiation is quite a bit more complex than the typical pop-sci explanation with virtual particles. But some intuitive justification is possible nevertheless.
I don't see how this event contributes to evaporation of the black
hole (, since the particles do not originate from the black hole).
You're missing a key point here.
When the pair was generated, those were virtual particles. After one side of the pair was absorbed by the black hole, and the other side was released, the released part is a real particle. Huge difference there - virtual vs real.
Virtual particles don't really exist the same way that you and me exist. They seem to exist for a very short time; the more energetic they are, the shorter the interval of their virtual "existence", per the Heisenberg equation. In many ways they are just a mathematical trick.
Think of the vacuum, where no real particles exist. Before, it's just vacuum. Right now, a virtual pair flickers briefly, then it's gone. In the future, it's vacuum again.
What was the energy before? Zero. What is the energy in the future? Zero. What's the energy during the flicker? Well, it basically zero, within the limits permitted by Heisenberg's equations. Bottom line is, virtual particles come and go, and they do not contribute to the energy balance of some empty chunk of space.
(I am ignoring here the concept of vacuum energy, for the sake of an intuitive explanation.)
But let's say one of the virtual particles gets trapped by the black hole, so it cannot annihilate with its counterpart. The other particle flies off in the opposite direction and escapes the black hole. What's worse, this is now a real particle - we've exceeded the duration permitted by the Heisenberg equations, so the one that escapes is not virtual anymore.
How did that particle become real?
This is a big issue, because virtual particles don't require an energy budget to briefly exist, while real particles do carry energy forever. Something prevented the virtual pair from annihilating itself, and boosted one of the components to the status of real particle. The virtual pair has zero energy. The real particle that gets away has non-zero energy. That energy has to come from somewhere.
It comes from the black hole. The black hole gives up some of its mass / energy (same thing) to boost one particle from virtual to real. The other particle is captured - but being virtual anyway, it doesn't really matter.
What this intuitive explanation doesn't say is how the boost actually happens. I dunno, magic. Somehow one of the virtual particles gets a chunk of energy from the black hole and becomes real.
Again, this is not the actual process. The actual process is more complex. This is just a pop-sci fairy tale.
EDIT: To hit closer to home, Hawking radiation is more like a close relative to the Unruh effect. Say an inertial observer sees empty space here in this chunk of volume. An accelerating observer would not see empty space in the same volume, but instead would see blackbody radiation. That's the Unruh effect.
Well, gravity and acceleration are the same thing, per general relativity. So the strong gravity near a black hole is equivalent to strong acceleration. Something similar to the Unruh effect must happen there. That's the Hawking radiation.
http://backreaction.blogspot.com/2015/12/hawking-radiation-is-not-produced-at.html
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
$endgroup$
1
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
$endgroup$
– Marko36
3 hours ago
3
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
add a comment |
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1 Answer
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$begingroup$
I'm going to give you an intuitive answer. Keep in mind, this is not the "actual" answer, as the Hawking radiation is quite a bit more complex than the typical pop-sci explanation with virtual particles. But some intuitive justification is possible nevertheless.
I don't see how this event contributes to evaporation of the black
hole (, since the particles do not originate from the black hole).
You're missing a key point here.
When the pair was generated, those were virtual particles. After one side of the pair was absorbed by the black hole, and the other side was released, the released part is a real particle. Huge difference there - virtual vs real.
Virtual particles don't really exist the same way that you and me exist. They seem to exist for a very short time; the more energetic they are, the shorter the interval of their virtual "existence", per the Heisenberg equation. In many ways they are just a mathematical trick.
Think of the vacuum, where no real particles exist. Before, it's just vacuum. Right now, a virtual pair flickers briefly, then it's gone. In the future, it's vacuum again.
What was the energy before? Zero. What is the energy in the future? Zero. What's the energy during the flicker? Well, it basically zero, within the limits permitted by Heisenberg's equations. Bottom line is, virtual particles come and go, and they do not contribute to the energy balance of some empty chunk of space.
(I am ignoring here the concept of vacuum energy, for the sake of an intuitive explanation.)
But let's say one of the virtual particles gets trapped by the black hole, so it cannot annihilate with its counterpart. The other particle flies off in the opposite direction and escapes the black hole. What's worse, this is now a real particle - we've exceeded the duration permitted by the Heisenberg equations, so the one that escapes is not virtual anymore.
How did that particle become real?
This is a big issue, because virtual particles don't require an energy budget to briefly exist, while real particles do carry energy forever. Something prevented the virtual pair from annihilating itself, and boosted one of the components to the status of real particle. The virtual pair has zero energy. The real particle that gets away has non-zero energy. That energy has to come from somewhere.
It comes from the black hole. The black hole gives up some of its mass / energy (same thing) to boost one particle from virtual to real. The other particle is captured - but being virtual anyway, it doesn't really matter.
What this intuitive explanation doesn't say is how the boost actually happens. I dunno, magic. Somehow one of the virtual particles gets a chunk of energy from the black hole and becomes real.
Again, this is not the actual process. The actual process is more complex. This is just a pop-sci fairy tale.
EDIT: To hit closer to home, Hawking radiation is more like a close relative to the Unruh effect. Say an inertial observer sees empty space here in this chunk of volume. An accelerating observer would not see empty space in the same volume, but instead would see blackbody radiation. That's the Unruh effect.
Well, gravity and acceleration are the same thing, per general relativity. So the strong gravity near a black hole is equivalent to strong acceleration. Something similar to the Unruh effect must happen there. That's the Hawking radiation.
http://backreaction.blogspot.com/2015/12/hawking-radiation-is-not-produced-at.html
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
$endgroup$
1
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
$endgroup$
– Marko36
3 hours ago
3
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
add a comment |
$begingroup$
I'm going to give you an intuitive answer. Keep in mind, this is not the "actual" answer, as the Hawking radiation is quite a bit more complex than the typical pop-sci explanation with virtual particles. But some intuitive justification is possible nevertheless.
I don't see how this event contributes to evaporation of the black
hole (, since the particles do not originate from the black hole).
You're missing a key point here.
When the pair was generated, those were virtual particles. After one side of the pair was absorbed by the black hole, and the other side was released, the released part is a real particle. Huge difference there - virtual vs real.
Virtual particles don't really exist the same way that you and me exist. They seem to exist for a very short time; the more energetic they are, the shorter the interval of their virtual "existence", per the Heisenberg equation. In many ways they are just a mathematical trick.
Think of the vacuum, where no real particles exist. Before, it's just vacuum. Right now, a virtual pair flickers briefly, then it's gone. In the future, it's vacuum again.
What was the energy before? Zero. What is the energy in the future? Zero. What's the energy during the flicker? Well, it basically zero, within the limits permitted by Heisenberg's equations. Bottom line is, virtual particles come and go, and they do not contribute to the energy balance of some empty chunk of space.
(I am ignoring here the concept of vacuum energy, for the sake of an intuitive explanation.)
But let's say one of the virtual particles gets trapped by the black hole, so it cannot annihilate with its counterpart. The other particle flies off in the opposite direction and escapes the black hole. What's worse, this is now a real particle - we've exceeded the duration permitted by the Heisenberg equations, so the one that escapes is not virtual anymore.
How did that particle become real?
This is a big issue, because virtual particles don't require an energy budget to briefly exist, while real particles do carry energy forever. Something prevented the virtual pair from annihilating itself, and boosted one of the components to the status of real particle. The virtual pair has zero energy. The real particle that gets away has non-zero energy. That energy has to come from somewhere.
It comes from the black hole. The black hole gives up some of its mass / energy (same thing) to boost one particle from virtual to real. The other particle is captured - but being virtual anyway, it doesn't really matter.
What this intuitive explanation doesn't say is how the boost actually happens. I dunno, magic. Somehow one of the virtual particles gets a chunk of energy from the black hole and becomes real.
Again, this is not the actual process. The actual process is more complex. This is just a pop-sci fairy tale.
EDIT: To hit closer to home, Hawking radiation is more like a close relative to the Unruh effect. Say an inertial observer sees empty space here in this chunk of volume. An accelerating observer would not see empty space in the same volume, but instead would see blackbody radiation. That's the Unruh effect.
Well, gravity and acceleration are the same thing, per general relativity. So the strong gravity near a black hole is equivalent to strong acceleration. Something similar to the Unruh effect must happen there. That's the Hawking radiation.
http://backreaction.blogspot.com/2015/12/hawking-radiation-is-not-produced-at.html
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
$endgroup$
1
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
$endgroup$
– Marko36
3 hours ago
3
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
add a comment |
$begingroup$
I'm going to give you an intuitive answer. Keep in mind, this is not the "actual" answer, as the Hawking radiation is quite a bit more complex than the typical pop-sci explanation with virtual particles. But some intuitive justification is possible nevertheless.
I don't see how this event contributes to evaporation of the black
hole (, since the particles do not originate from the black hole).
You're missing a key point here.
When the pair was generated, those were virtual particles. After one side of the pair was absorbed by the black hole, and the other side was released, the released part is a real particle. Huge difference there - virtual vs real.
Virtual particles don't really exist the same way that you and me exist. They seem to exist for a very short time; the more energetic they are, the shorter the interval of their virtual "existence", per the Heisenberg equation. In many ways they are just a mathematical trick.
Think of the vacuum, where no real particles exist. Before, it's just vacuum. Right now, a virtual pair flickers briefly, then it's gone. In the future, it's vacuum again.
What was the energy before? Zero. What is the energy in the future? Zero. What's the energy during the flicker? Well, it basically zero, within the limits permitted by Heisenberg's equations. Bottom line is, virtual particles come and go, and they do not contribute to the energy balance of some empty chunk of space.
(I am ignoring here the concept of vacuum energy, for the sake of an intuitive explanation.)
But let's say one of the virtual particles gets trapped by the black hole, so it cannot annihilate with its counterpart. The other particle flies off in the opposite direction and escapes the black hole. What's worse, this is now a real particle - we've exceeded the duration permitted by the Heisenberg equations, so the one that escapes is not virtual anymore.
How did that particle become real?
This is a big issue, because virtual particles don't require an energy budget to briefly exist, while real particles do carry energy forever. Something prevented the virtual pair from annihilating itself, and boosted one of the components to the status of real particle. The virtual pair has zero energy. The real particle that gets away has non-zero energy. That energy has to come from somewhere.
It comes from the black hole. The black hole gives up some of its mass / energy (same thing) to boost one particle from virtual to real. The other particle is captured - but being virtual anyway, it doesn't really matter.
What this intuitive explanation doesn't say is how the boost actually happens. I dunno, magic. Somehow one of the virtual particles gets a chunk of energy from the black hole and becomes real.
Again, this is not the actual process. The actual process is more complex. This is just a pop-sci fairy tale.
EDIT: To hit closer to home, Hawking radiation is more like a close relative to the Unruh effect. Say an inertial observer sees empty space here in this chunk of volume. An accelerating observer would not see empty space in the same volume, but instead would see blackbody radiation. That's the Unruh effect.
Well, gravity and acceleration are the same thing, per general relativity. So the strong gravity near a black hole is equivalent to strong acceleration. Something similar to the Unruh effect must happen there. That's the Hawking radiation.
http://backreaction.blogspot.com/2015/12/hawking-radiation-is-not-produced-at.html
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
$endgroup$
I'm going to give you an intuitive answer. Keep in mind, this is not the "actual" answer, as the Hawking radiation is quite a bit more complex than the typical pop-sci explanation with virtual particles. But some intuitive justification is possible nevertheless.
I don't see how this event contributes to evaporation of the black
hole (, since the particles do not originate from the black hole).
You're missing a key point here.
When the pair was generated, those were virtual particles. After one side of the pair was absorbed by the black hole, and the other side was released, the released part is a real particle. Huge difference there - virtual vs real.
Virtual particles don't really exist the same way that you and me exist. They seem to exist for a very short time; the more energetic they are, the shorter the interval of their virtual "existence", per the Heisenberg equation. In many ways they are just a mathematical trick.
Think of the vacuum, where no real particles exist. Before, it's just vacuum. Right now, a virtual pair flickers briefly, then it's gone. In the future, it's vacuum again.
What was the energy before? Zero. What is the energy in the future? Zero. What's the energy during the flicker? Well, it basically zero, within the limits permitted by Heisenberg's equations. Bottom line is, virtual particles come and go, and they do not contribute to the energy balance of some empty chunk of space.
(I am ignoring here the concept of vacuum energy, for the sake of an intuitive explanation.)
But let's say one of the virtual particles gets trapped by the black hole, so it cannot annihilate with its counterpart. The other particle flies off in the opposite direction and escapes the black hole. What's worse, this is now a real particle - we've exceeded the duration permitted by the Heisenberg equations, so the one that escapes is not virtual anymore.
How did that particle become real?
This is a big issue, because virtual particles don't require an energy budget to briefly exist, while real particles do carry energy forever. Something prevented the virtual pair from annihilating itself, and boosted one of the components to the status of real particle. The virtual pair has zero energy. The real particle that gets away has non-zero energy. That energy has to come from somewhere.
It comes from the black hole. The black hole gives up some of its mass / energy (same thing) to boost one particle from virtual to real. The other particle is captured - but being virtual anyway, it doesn't really matter.
What this intuitive explanation doesn't say is how the boost actually happens. I dunno, magic. Somehow one of the virtual particles gets a chunk of energy from the black hole and becomes real.
Again, this is not the actual process. The actual process is more complex. This is just a pop-sci fairy tale.
EDIT: To hit closer to home, Hawking radiation is more like a close relative to the Unruh effect. Say an inertial observer sees empty space here in this chunk of volume. An accelerating observer would not see empty space in the same volume, but instead would see blackbody radiation. That's the Unruh effect.
Well, gravity and acceleration are the same thing, per general relativity. So the strong gravity near a black hole is equivalent to strong acceleration. Something similar to the Unruh effect must happen there. That's the Hawking radiation.
http://backreaction.blogspot.com/2015/12/hawking-radiation-is-not-produced-at.html
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
edited 4 hours ago
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
answered 4 hours ago
Florin AndreiFlorin Andrei
12.7k12844
12.7k12844
1
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
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– Marko36
3 hours ago
3
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
add a comment |
1
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
$endgroup$
– Marko36
3 hours ago
3
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
1
1
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
$endgroup$
– Marko36
3 hours ago
$begingroup$
This "pop-sci fairytale", as you called it yourself, is quite a pleasant read, I even laughed. Thanks. But it is this "I dunno magic" I am after: how does the virtual particle get it's real state (besides magic) and how does this contribute to BH evaporation, having that nothing can escape the black hole..
$endgroup$
– Marko36
3 hours ago
3
3
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
@Marko Also see math.ucr.edu/home/baez/physics/Relativity/BlackHoles/…
$endgroup$
– PM 2Ring
2 hours ago
add a comment |
Marko36 is a new contributor. Be nice, and check out our Code of Conduct.
Marko36 is a new contributor. Be nice, and check out our Code of Conduct.
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Forget about virtual particle pairs, that's more like a metaphor. The thing is, black holes emit radiation, regardless of how they do that. Radiation carries energy, which must come from somewhere, there's no free lunch here. But energy equals mass. It all comes out of the black hole's "bank account" of mass, because that's the only thing nearby.
$endgroup$
– Florin Andrei
5 hours ago
$begingroup$
Ok, thanks @Florin Andrei, but virtual particles are commonly accepted as a real thing, so how (much) are they metaphorical? Why? Also, black hole radiation is explicitly explained by them. Should they be a metaphorical concept, what is this black hole radiation, you mentioned, really? Also assuming that "nothing can escape the black hole, not even EM radiation".
$endgroup$
– Marko36
5 hours ago
$begingroup$
@Marko36 It's not that virtual particles are a metaphor in general (although in a sense they are, all particles, virtual or otherwise are just a way of viewing some aspects of the underlying fields), but they are not really a very good explanation of Hawking Radiation. This, however, doesn't answer your question. I look forward to seeing an answer.
$endgroup$
– Steve Linton
4 hours ago
1
$begingroup$
You might like to check out math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html and physics.stackexchange.com/questions/185110/… and other related questions on Physics about virtual particles.
$endgroup$
– PM 2Ring
2 hours ago
$begingroup$
This question on physics (and its accepted answer come the closest I have yet found to addressing this question) but they still don't answer it completely. physics.stackexchange.com/questions/251385/….
$endgroup$
– Steve Linton
15 mins ago