# Strange Black Hole Question

#### NateTG

Science Advisor
Homework Helper
According to SR, a photon has an equivalent mass of
h / c &lambda;
where h is plank's constant, c is the speed of light, and lambda is the photon's wavelength.

So, at some point the equivalent mass of the photon should be sufficient to cause a black hole. (Using the simplified formula I got something like a 10^ -35m wavelength.)

Questions:
1. Can a solitary photon have sufficient energy to become a black hole in GR?

2. If the answer to 1 is yes, is it possible to have frames of reference where the photon is not a black hole -- for example red shifting the photon to reduce it's energy? If so, how does that frame of reference experience hawking radiation associated with the black hole?

3. If the answer to 1 is no, is there some limit to the maximum energy that a photon can have, and can a black hole be disolved by spontaneous massive energy to matter conversion inside the Schwartzchild radius?

Related Special and General Relativity News on Phys.org

#### Herra Tohtori

Well, what is the difference between energy's matter form and energy form? It has been suggested that the properties of mass are caused by a particle called Higgs' boson. This particle would cause the inertia. Could it also be the fundamental reason to gravity? I suppose it could. Actually, I think that inertia is caused by the bending of space-time. An accelerating object forms a shockwave (I can't describe it by any other word, sorry for that) which is actually the bending speed of the space changing when the object accelerates. That causes a "drag" to acceleration. Note: an object moving with default speed doesn't meet any drag in empty space.

This also explains why massless objects cannot be accelerated to the speed of light, c. If an object would accelerate to c, it would drop its gravitational effects behind it, and that's of course impossible.

So. The photon may have (and has, otherwise it wouldn't exist)energy, but it doesn't have the Higgs' boson in it, so it doesn't have the effects of mass. It just goes on with the speed of light, straight(shortest)line between two points. Thus, it cannot form a black hole. And there is no limit for the energy of a single photon. But i suppose thet most energetic photons would be created in annihilation reactions. I can't think of any reactions more powerful...

#### jcsd

Science Advisor
Gold Member
Originally posted by NateTG
According to SR, a photon has an equivalent mass of
h / c &lambda;
where h is plank's constant, c is the speed of light, and lambda is the photon's wavelength.

So, at some point the equivalent mass of the photon should be sufficient to cause a black hole. (Using the simplified formula I got something like a 10^ -35m wavelength.)

Questions:
1. Can a solitary photon have sufficient energy to become a black hole in GR?

2. If the answer to 1 is yes, is it possible to have frames of reference where the photon is not a black hole -- for example red shifting the photon to reduce it's energy? If so, how does that frame of reference experience hawking radiation associated with the black hole?

3. If the answer to 1 is no, is there some limit to the maximum energy that a photon can have, and can a black hole be disolved by spontaneous massive energy to matter conversion inside the Schwartzchild radius?
What you have actually calculated (roughly anyway, as h-bar is preferred to h in Planck units these days) is the Planck length ~10-35.

1) Your not the first person to think of this, but the answer to this question is almost certainly 'no'. For example a neutron star that is travelling at relativistic speeds will not collaspe into a black hole, as it only matters what's going on in the rest frame of the object (though a phton doesn't have one).

2) see above.

3) Some think that the maximum energy a phton can have is the one associated with the wavelength calculated, but it is not known what happens at the Planck scale, so thisa is more idle speculation. No a blackhole can't be dissolved by a sponateous converison of mass to energy within it's radius.

#### NateTG

Science Advisor
Homework Helper
Re: Re: Strange Black Hole Question

Originally posted by jcsd
What you have actually calculated (roughly anyway, as h-bar is preferred to h in Planck units these days) is the Planck length ~10-35.

1) Your not the first person to think of this, but the answer to this question is almost certainly 'no'. For example a neutron star that is travelling at relativistic speeds will not collaspe into a black hole, as it only matters what's going on in the rest frame of the object (though a phton doesn't have one).
Yeah, but I googled for it, and got no real answers. I'll go look up the plank length now.

Originally posted by jcsd

3) Some think that the maximum energy a phton can have is the one associated with the wavelength calculated, but it is not known what happens at the Planck scale, so thisa is more idle speculation. No a blackhole can't be dissolved by a sponateous converison of mass to energy within it's radius.
I don't understand: According to your answer to 1, what is necessary for black hole formation is rest mass, but if a black hole converts to energy, there should be a reduction in rest mass - so it should be possible to dissolve it.

#### Ambitwistor

Re: Re: Re: Strange Black Hole Question

Originally posted by NateTG
Yeah, but I googled for it, and got no real answers.
It's basically the same as this question:

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_fast.html

I don't understand: According to your answer to 1, what is necessary for black hole formation is rest mass, but if a black hole converts to energy, there should be a reduction in rest mass - so it should be possible to dissolve it.
I don't know what it means for a black hole to "convert to energy"; there is no matter or radiation inside a black hole -- it is vacuum. (Or rather, any matter or radiation inside the hole quickly gets eradicated at the singularity.)

Anyway, there isn't any clear distinction between rest mass and energy, because of E=mc2. We know that energy contributes to rest mass.

#### ranyart

Originally posted by NateTG
According to SR, a photon has an equivalent mass of
h / c &lambda;
where h is plank's constant, c is the speed of light, and lambda is the photon's wavelength.

So, at some point the equivalent mass of the photon should be sufficient to cause a black hole. (Using the simplified formula I got something like a 10^ -35m wavelength.)

Questions:
1. Can a solitary photon have sufficient energy to become a black hole in GR?

2. If the answer to 1 is yes, is it possible to have frames of reference where the photon is not a black hole -- for example red shifting the photon to reduce it's energy? If so, how does that frame of reference experience hawking radiation associated with the black hole?

3. If the answer to 1 is no, is there some limit to the maximum energy that a photon can have, and can a black hole be disolved by spontaneous massive energy to matter conversion inside the Schwartzchild radius?
What we have here is the classic Hawking Area function of Blackholes.

The first thing to understand is how a photon approaches a Blackhole Horizon, at a precise location it gets trapped between 'shells',(I will only define these as being:
1) 3-DIMENSIONAL OUTERSHELL.
2) 2-DIMENSIONAL CENTRALSHELL.
3) 1-DIMENSIONAL INNERSHELL.

There are some complicated Holographic details, but the basis is that the photon can rebound between the outershell and centralshell, thus one gets emmited virtual particles that dance around the 3-dimensional surface area, this adds to the surface-tension of a blackhole, and as with the corona around our Sun, can have thermal variations.

Any photon that has entered/crossed the 2-dimensional barrier will never return, it must continue onwards and it is now forever part of an opposing Entropy, it cannot pass information backwards in time(out into our Galaxy for instance), but it's thermal arrow has some interesting properties!

The 1-dimensional singularity/Gravity realm is really interesting! Im in no doubt you understand E=MC2, but let me give you a lesson in deep-field-exchange consequences of the famous equation.

In its early form Einstein knew the consequences for the equation as it stood in 3+1 dimensions, but when you transform the equation into inter-dimensional area's, there is a lot more to it than meets the eye! for instance Exchanging Mass for hv energy, is dimensional bound into 4-dimensional space. The moment you transend into another dimension, the E=MC2 has a quite different effect.

As a photon goes from 4-d >>> 3-d >> 2-d >.....the exchnage paramiter of the Equation also alters..for a simplistic view it ends up just as a Gravity function..+ or -....

Just see that Blackholes hold Galaxies together as the Spacetime of General Relativity, the space(the intervening space between Galaxies)is not Spacetime!...its a whole new ballgame, a sort of Negative Spacetime! opposing in everyway.

Last edited:

#### jcsd

Science Advisor
Gold Member
ranyart, Nate was asking a serious question, ther is a forum on the boards for the nonsense you've posted and this is not it.

#### NateTG

Science Advisor
Homework Helper
Originally posted by Ambitwistor

I don't know what it means for a black hole to "convert to energy"; there is no matter or radiation inside a black hole -- it is vacuum. (Or rather, any matter or radiation inside the hole quickly gets eradicated at the singularity.)
Let's say that I have a black hole with mass equal to about 10^-9 kilograms. Let's assume that the matter inside the Schwartzschild radius has not formed a singularity (AFAIK singulatities are not acutally necessary for black holes to form.) If all of the matter inside the black hole was then converted to a small number of photons, how would the black hole continue to exisrt?

#### ranyart

Originally posted by jcsd
ranyart, Nate was asking a serious question, ther is a forum on the boards for the nonsense you've posted and this is not it.
Define the nonesense in my post, you can start by showing me a Three-Dimensional Blackhole.

#### jcsd

Science Advisor
Gold Member
Originally posted by NateTG
Let's say that I have a black hole with mass equal to about 10^-9 kilograms. Let's assume that the matter inside the Schwartzschild radius has not formed a singularity (AFAIK singulatities are not acutally necessary for black holes to form.) If all of the matter inside the black hole was then converted to a small number of photons, how would the black hole continue to exirt?
There's always a singularity associated with a black hole, remeber nothing whatsover that's going on inside the black hole will affect anything outside the event horizon (or indeed futher away from the singularity than the event).

#### Ambitwistor

Originally posted by NateTG
Let's say that I have a black hole with mass equal to about 10^-9 kilograms. Let's assume that the matter inside the Schwartzschild radius has not formed a singularity (AFAIK singulatities are not acutally necessary for black holes to form.)
The singularity theorems say otherwise.

If all of the matter inside the black hole was then converted to a small number of photons, how would the black hole continue to exisrt?
No change in the configuration of matter or radiation inside the black hole can produce an effect that propagates outwards as far as the event horizon, let alone outside of it -- that's what it means for something to be a black hole: nothing that happens inside of it can ever influence anything outside of it. Once the black hole forms, it holds itself together by its own gravitation, regardless of what happens to the matter or radiation that went into forming it.

#### jcsd

Science Advisor
Gold Member
Originally posted by ranyart
Define the nonesense in my post, you can start by showing me a Three-Dimensional Blackhole.
First line: "what we have here is the classic Hawking Area function of Blackholes"; total nonsense, you might be referring to the Bekenstein-Hawking entropy of a black hole (which is related to to the surface area of a BH), but a) it's semi-classical and b) completely irrelavent.

Also what the hell are these shell's, you might possibly be refrring to the event horizon and phtonsphere, but it's still nonsensical esp. as Scwarzchild space is has three spatial dimensions.

I could go on, it's diffcult to pick out anything in your post that wasn't nonsense.

#### ranyart

Originally posted by jcsd
First line: "what we have here is the classic Hawking Area function of Blackholes"; total nonsense, you might be referring to the Bekenstein-Hawking entropy of a black hole (which is related to to the surface area of a BH), but a) it's semi-classical and b) completely irrelavent.

Also what the hell are these shell's, you might possibly be refrring to the event horizon and phtonsphere, but it's still nonsensical esp. as Scwarzchild space is has three spatial dimensions.

I could go on, it's diffcult to pick out anything in your post that wasn't nonsense.
Just for starters I may refer you to this:http://citebase.eprints.org/cgi-bin/citations?id=oai:arXiv.org:gr-qc/9310026 [Broken]

If you bother to read any pre-prints at all that is, there will be more.

Last edited by a moderator:

#### ranyart

Originally posted by jcsd
First line: "what we have here is the classic Hawking Area function of Blackholes"; total nonsense, you might be referring to the Bekenstein-Hawking entropy of a black hole (which is related to to the surface area of a BH), but a) it's semi-classical and b) completely irrelavent.

Also what the hell are these shell's, you might possibly be refrring to the event horizon and phtonsphere, but it's still nonsensical esp. as Scwarzchild space is has three spatial dimensions.

I could go on, it's diffcult to pick out anything in your post that wasn't nonsense.
Then:http://ernie.ecs.soton.ac.uk/opcit/cgi-bin/pdf?id=oai%3AarXiv%2Eorg%3Ahep%2Dth%2F9803131 [Broken]

Last edited by a moderator:

#### jcsd

Science Advisor
Gold Member
Ranyart, these papers do not really relate to the topic at all and they do not much relate to what you have said either, furthermore they are both of a speculative nature rather than dealing with well-known theory.

#### jeff

Science Advisor
Originally posted by NateTG
Can a solitary photon have sufficient energy to become a black hole in GR?
A massless particle can't form a black hole because event horizons are null hypersurfaces and the world-lines of gravitational singularities can't intersect their event horizons.

#### ranyart

Originally posted by jcsd
First line: "what we have here is the classic Hawking Area function of Blackholes"; total nonsense, you might be referring to the Bekenstein-Hawking entropy of a black hole (which is related to to the surface area of a BH), but a) it's semi-classical and b) completely irrelavent.

Also what the hell are these shell's, you might possibly be refrring to the event horizon and phtonsphere, but it's still nonsensical esp. as Scwarzchild space is has three spatial dimensions.

I could go on, it's diffcult to pick out anything in your post that wasn't nonsense.
You do not have to tell me that you do not understand that a photon bounces around matter in 4-dimensional space, and E=mC2 is the transformation equation that governs our understanding of this reality.

But the same E=mC2 has significant variations with compacted dimensional analysis. Firstly the energy we are used to in measure terms, becomes invisible, you cant use photons to measure effects in a 2-dimensional zone, why?..because the are 3-Dimensional quantities themselves, thats why we see things, they give substance to distance of objects (3-dimensional objects).

Havn't you heard of Dark-photons? Go back and study Realitivity and seek out the E=mC2, and place this in a non-three-dimensional field, you may learn something.

#### Ambitwistor

Originally posted by jeff
A massless particle can't form a black hole because event horizons are null hypersurfaces and the world-lines of gravitational singularities can't intersect their event horizons.
I'm not sure that I understand this argument. Two questions:

Does your argument imply that black holes can't form from electromagnetic radiation?

What is the "worldline of a singularity"? Are you talking about timelike black hole singularities?

#### jeff

Science Advisor
Originally posted by Ambitwistor
Does your argument imply that black holes can't form from electromagnetic radiation?
No. I was careful to specify a single massless particle. (Note also that the original question specified a "solitary" photon).

Originally posted by Ambitwistor
What is the "worldline of a singularity"? Are you talking about timelike black hole singularities?
In the context of the original question, do you know of technical qualifications that must be made in describing the motion of gravitational singularities that invalidate the basic geometrical point of my argument?

Last edited:

#### Ambitwistor

Originally posted by jeff
In the context of the original question, do you know of technical qualifications that must be made in describing the motion of gravitational singularities that invalidate the basic geometrical point of my argument?
I still don't really understand the point of your argument, and I don't quite know what it has to do with black hole singularities. The black hole singularities I'm familiar with are spacelike, so I'm not sure what it means to describe their motion.

#### jeff

Science Advisor
Originally posted by Ambitwistor
The black hole singularities I'm familiar with are spacelike
I apologize if my responses seem cryptic. They're not meant to be. I think I do have an inkling of what might be bothering you about the point I'm trying to make.

Perhaps I should've qualified what I meant by world-line of a singularity. But although I think I might know what you mean by a singularity being spacelike, it would help me to know for certain.

In any event, my argument may be viewed as an attempt in the context of the original question to explain in terms of black hole geometry the following excerpt from the comments made by john baez to which you gave a link:

In a frame of reference stationary with respect to the object, it has only rest mass energy and will not form a black hole unless its rest mass is sufficient._ If it is not a black hole in one reference frame, then it cannot be a black hole in any other reference frame.

#### Ambitwistor

Well, I certainly agree with the FAQ statement. I also agree that classically, a single massless particle cannot form a black hole. (I'm not so sure about quantum gravity, but then, who is?)

#### jcsd

Science Advisor
Gold Member
Originally posted by ranyart
You do not have to tell me that you do not understand that a photon bounces around matter in 4-dimensional space, and E=mC2 is the transformation equation that governs our understanding of this reality.

But the same E=mC2 has significant variations with compacted dimensional analysis. Firstly the energy we are used to in measure terms, becomes invisible, you cant use photons to measure effects in a 2-dimensional zone, why?..because the are 3-Dimensional quantities themselves, thats why we see things, they give substance to distance of objects (3-dimensional objects).

Havn't you heard of Dark-photons? Go back and study Realitivity and seek out the E=mC2, and place this in a non-three-dimensional field, you may learn something.
Oh please shut up.

#### jeff

Science Advisor
Originally posted by Ambitwistor
...black hole singularities...are spacelike...
Singularities lie on the unphysical boundary of spacetime where geometry is undefined.

Originally posted by Ambitwistor
.. timelike black hole singularities?
By "world-line of the singularity" (the quotation marks would've been a good idea) I meant a curve in the unphysical completion of M.

Originally posted by Ambitwistor
I still don't really understand the point of your argument
Yeah, I think we can safely forget about that bit of nonsense.

#### Ambitwistor

Originally posted by jeff
By "world-line of the singularity" (the quotation marks would've been a good idea) I meant a curve in the unphysical completion of M.
That's what I mean when I talk about whether singularities are spacelike or timelike. For Schwarzschild, Kerr, etc. holes, that curve is spacelike. (It looks timelike in Schwarzschild coordinates, sort of like "the worldline of a particle", but that's because r and t flip signature inside the horizon -- it's really a spacelike surface. That's why everyone hits the singularity: it's in the future of everyone inside the horizon.)

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving