LHC Black Holes

I think saying the particle pair "takes energy" from the field is hand waving. The energy in the heavy nuclei is in the nuclei, not the field. What is the mechanism to transfer energy to the particle pair? Exactly how does the nuclei loose energy? Do they have less momentum? Did they somehow lose mass?

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Rick C

Fine, but quantum theory has been verified repeatedly. Hawking radiation has not.

I don't have problems with weird things. It's not the weirdness that is at issue. It's the lack of connection between the particle pair and the black hole.

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Rick C

Laws fit the data until they don't, then we get new laws.

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Rick C

I wish I could ask him questions like, "does the particle *actually* fall into the black hole" or "is there an observer who can see the particle fall into the black hole"? If either is true, then the energy to create the particle pair must actually cross the boundary. Or does this other observer see no particle pair?

It's never been clear to me what you would see from inside a black hole looking out. I don't think the boundary is invisible. I expect it is a massive disturbance so that you can tell clearly what is inside and what is outside. For example, I believe inside a black hole, an object (if there are objects) which is closer to the event horizon than yourself, would be totally visible, you would see front and back.

I recall someone here was saying our entire universe could be inside a black hole. Then clearly the full contents of the black hole is not on the surface... I believe. Are we actually on the 3D surface of a 4D superuniverse? Or maybe the 4D surface of a 5D superuniverse?

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Rick C

I am thinking of a black hole as a sphere defined by the Schwarzschild radius because that is what everyone talking about Hawking radiation uses. I know it is not a "physical" boundary like a table, but in reality it *is* a physical boundary in that it can not be crossed from inside to outside... by anything supposedly.

It has "always" existed? I don't follow that. It was created outside the event horizon. But this is not the way Susskind describes it. He says neither particle falls into the black hole, rather they are made real by virtue of the high gravitational gradient.

Everything I've read says *nothing* can cross from the inside to the outside. As you said above, the escape velocity is higher than the speed of light. Are you suggesting that light created just inside the Schwarzschild radius can emerge but will eventually fall back, *if* it doesn't interact with something else?

If that worked with the black hole they wouldn't be very black, would they? There is a contradiction here. No?

I think you are mistaken. Once it crosses the Schwarzschild radius, it can never escape according to everyone I have read on this.

Ok, it moves forward, then backward, then what?

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Rick C

Yes. This is very weird to think about because there are so many things happening. Gravity bends space-time. If it bends so that the escape velocity is faster than the speed of light, does this do something to space-time like break it? lol

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Rick C

No, that doesn't help. The entire universe is inside the black hole's gravity well according to this way of viewing it.

So the space ship can cross the event horizon, turn around and fly back and kill the observer?

I think that is the issue, time. In a gravitational field time slows as viewed by an outside observer. Inside the black hole when the spaceship turns around it has actually crossed the zero point and is traveling backward in time if the outside observer could see it. So when it escapes the black hole's event horizon it has traveled so far back in time the observer wasn't born yet.

No, I am pretty sure the spaceship can't cross the event horizon from the inside out.

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Rick C

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Rick C

So there is the energy in the mass and additional energy in the field? Wow, so conservation of energy is not a law?

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Rick C

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Yes, and yes.

What makes you think that energy stored as mass and the energy that can b e extracted from gravitational field it produces are the same thing? They'r e not.

There is energy in the mass of an electron and additional energy in its e lectric field. If you get that you should have no trouble accepting the fac t that there's still more in its tiny gravitational field.

Mark L. Fergerson

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There is a physics stack exchange,

where you might find people who know and care about the mechanism. (and want to talk about it.)

George H.

So how much energy is in the electric field of the electron? How can we tap this energy source?

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Rick C

No. Virtual particles have mass, but not necessarily the same mass as the ir real counterparts. Look up "mass shell".

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It's not a source of energy, it's a source of potential that affects the motion of other electrons (and other particles) depending on their position in the potential field. Think volts per meter.

Typically, by accumulating a lot of them in one place and allowing opposi tely-charged particles to fall through their superposed fields, or allowing those fields to repel similarly-charged particles. Think lightning, Wimshu rst machines, particle accelerators, vacuum tubes, FETs... anything that co mes under the heading "electronics" by definition.

Mark L. Fergerson

But people are saying the electric and gravitational fields have energy. Think they believe you?

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Rick C

You are making distinctions that don't actually exist at this level. Mass and energy are, in some ways, equivalent. Sometimes you can treat them as the same thing, sometimes you think of them as converting from one form to the other. If you take some protons and neutrons, and join them together into a single nucleus, the mass of the nucleus is lower than the sum of the masses of the protons and neutrons. The missing mass is released as energy. (This is how fusion in the sun works.)

I also don't think you can make such a distinction between the black hole as an entity, and its fields (gravitational, electromagnetic, etc.) since those fields cover all aspects of how outside observers could ever detect or interact with the black hole.

True. (Though as I linked earlier, Hawking radiation from sonic black holes has been verified.)

You wanted a nice mechanical explanation. I'm just saying that you are not going to get one.

You might also try asking in a physics newsgroup. I am trying my best to give some explanations, but I can't claim to have a good understanding of this stuff - I'm just an interested layman in this field.

True. Everything has a certain amount of potential energy as a result of its distance from the black hole.

(As an aside, I suspect that this is not exactly true - that quantisation of gravitons limits the range and effect of the force of gravity, and that this is the reason for the unexpected increase in the expansion rate of the universe. I think that a more refined model of gravity that takes quantum effects into account for weak gravity over long distances will replace "dark energy" models.)

No, because the times are completely different. (Yes, I realise that is a complete failure as an explanation. There is a time paradox here somewhere that I can't figure out. Sorry!)

I am pretty sure that it can, because it can't see the event horizon (certainly not from the inside). But I am also pretty sure that I can't explain it well enough to myself, never mind to anyone else. And if someone knows better, then I will be happy to change my ideas here.

Certainly the event horizon (defined by the Schwarzschild radius for an uncharged, non-rotating black hole - but more complex in general) is where you see the Hawking radiation appear. But you get the virtual particle pairs further away too - the strongest radiation will occur near the event horizon, but not too near (since both particles would be likely to fall in). And I don't see any reason why you would not also get particle pairs appearing inside the event horizon too.

Yes, that is what I am suggesting.

It may be that I am missing something (probably a time effect), but that is how "escape velocity" works for every other source of gravity - why should a black hole be any different?

No. "Black" in the scientific sense means an absorption and emission spectrum determined purely by temperature. Most of the light you get from the sun is "black body radiation".

And anyway, "black holes" were christened long before Hawking radiation or other details were figured out. And we have found black holes precisely because they are anything but "black" (in the colloquial sense) - they are surrounded by hot glowing disks.

Actually, "then" is a bad word to use here (I know I used it) as it implies a sequence in time. The particle just goes round in a loop in space-time.

Yes.

Just because something has energy, does not mean it can be extracted - at least, not without changing that something. If you hold a brick, it has potential energy from the earth's gravity. To extract that, you must change the brick - by letting it fall. That energy is converted to other forms of energy (such as sound energy, after it hits your toe).