# Particles near black holes

Discussion in 'Physics & Math' started by RoccoR, Aug 12, 2013.

1. ### RoccoRRegistered Senior Member

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144
et al,

(MENTAL OBSERVATION)

I have listened to many lectures, and heard a continuous theme commonly expressed, saying (paraphrased) that "relativity" does an excellent job explaining the very large and the very fast, but not the very small; which "quantum mechanics" does very well. But that the two do not combine well.

(HYPOTHETICAL)

Suppose I describe a region of space-time. And that region of space-time had a very massive star that collapsed in on itself, creating a core that was so dense, that it compressed the matter within the core to such a degree that all energy was squeezed out. All atomic and subatomic particle movement was so crushed together that all movement stopped.

With all movement stopped, there was absolutely no heat generated (absolute zero), but because of the extensive mass, an inescapable gravitational field was formed. Any atomic or subatomic particle (even light), caught within the gravitation field, could not escape. As this captured mass was drawn into the center of this massive gravitational field at an ever increasing rate of acceleration (at a rate approaching c^2) it gradually begins to transform all its energy into mass [m=(c^2)/E]. The converted energy (into mass) then accumulates on the core at absolute zero.

(QUESTIONs)

• Is such a region of space-time possible?
• What would prevent such an occurrence?
• What would we call such a region?
• Could such a region of space create a gravitational lens effect?
• Could such a region of space tie "relativity" and "quantum mechanics" together?

Most Respectfully,
R

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3. ### originHeading towards oblivionValued Senior Member

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11,693
OK:shrug:

(MENTAL OBSERVATION)

You have no understanding of physics

(HYPOTHETICAL)

Your lack of physics knowledge means that your ideas are worth less than nothing.

(QUESTIONs)

• Why try to come up with hypothesis on a subject in which you are ignorant?
• What makes you think watching a couple of programs on the science channel makes you able to understand black holes?
• Why do you always state the obvious with titles?
• Why resurect a 7 year old thread for this!?
• Why, oh why would you invite people to tear you apart - do you know your ideas are silly and just enjoy abuse?

Happy now?

Hope I made your day....:shrug:

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5. ### brucepValued Senior Member

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4,098
Hi R

GR is a classical theory of gravity. It's not a quantum theory. They have different domains of applicability. GR will never describe quantum phenomena because it was never meant to. The rest of the story is pretty darn interesting. Quantum gravity is the theoretical attempt to describe gravitational phenomena in the quantum domain of applicability. In essence describe what's at the center of black holes and most importantly quantum gravitational effects when there was only one force of nature during the Planck era at the beginning of our universe. Huge 'degree of difficulty' on this dive. All this applies to your other question. What you imagined about 'your region of spacetime' isn't possible as science understands it at this time. I know you like to read interesting things so I'm going give you some things to read about. The first is the Pauli Exclusion Principle and how electron degeneracy stops the gravitational collapse at dwarf stars, neutron degeneracy stops the gravitational collapse at neutron stars. 2nd read is about collapsed stars and the astrophysics associated with them. That's what science knows about real high density matter regions. Like what you imagined but what the scientific literature actually says about 'high density regions' of matter. We actually have an expert 'on the path towards' a theoretical model of quantum gravity. That would be Alphanumeric. Always an interesting subject with many interesting developments. Reading about the Pauli Exclusion Principle, in an Asimov science novel on stellar gravitational collapse [one of my favorite people of all time], really got me interested in the subject of physics describing our universe.

Forgot to say: The final stage of gravitational collapse results in the singularity at the center of black holes. They're working on it. I got the confidence in these folks.

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7. ### Fednis48Registered Senior Member

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brucep's overview sums it up pretty well. I'd just add that the main flaw in your idea is that it doesn't make sense for gravity to "squeeze the energy" out of a system; unlike water in a sponge, energy doesn't fill up the space between particles of matter. Apart from that, it looks like you've provided a reasonable (if oversimplified) description of how black holes form. Not sure if that was your original intent.

8. ### RoccoRRegistered Senior Member

Messages:
144
origin,

Thanks, I really appreciate your insight.

(COMMENT)

Posing a question is how I learn.

In the future, if I should ask a question, please feel free to ignore it. I wouldn't want to waste your most precious and valuable time; or break a blood vessel.

Many Thanks Again for Your Inciteful View,
R

Last edited: Aug 12, 2013
9. ### RoccoRRegistered Senior Member

Messages:
144
brucep,

Thanks very much for your time; I really appreciate it.

(COMMENT)

I will definitely look into your suggested readings.

Most Respectfully,
R

10. ### RoccoRRegistered Senior Member

Messages:
144
Fednis48,

Many thanks.

(COMMENT)

Well, I tried to condense it the key ideas.

The spaghetti effect; the appearance that material must fall into such a region faster than the speed of light -- if light cannot escape. And the question of what happened to all the energy that was dragged-in to the region. The material must accelerate at enormous speeds before it actually reaches the center.

But, I don't want to bore anyone with thoughts from an old man. I just wanted to rule out what seemed obvious - that the acceleration and the reverse of GR (energy into matter) had any impact on the process.

Again, many thanks for your insight.

I notice that you all talk on a level many times greater than my own, but --- every now an then you might hear a stupid question. It will probably be from me.

Most Respectfully,
R

11. ### Aqueous Idflat Earth skepticValued Senior Member

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6,152
Hopefully the insights given here incite you to greater insight. (I was going to say Freudian slip? but my own slips got in the way

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)

You might want to begin with something that is known. A neutron star, for example, might be a good starting point for considering what happens what matter becomes very dense.

12. ### brucepValued Senior Member

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4,098
It's a good question. Make sure you read about the limits set by the Pauli Exclusion Principle. It's really interesting to read about the inside of a gravitational collapsed object which in the process becomes one of the most stable objects in the universe. For instance why does a Supernova result in a neutron star or a black hole? Why doesn't a Supernova neutron star remnant core come apart during collapse? Since you mentioned the path inside the black hole: Using a local proper frame metric we can evaluate the path of an object from r=2M to the limit r>0. It turns out the average proper velocity over that path is 3/2c. The three great uses of GR is to test it's predictions in the weak field [because we can], evaluate the strong field physics experimentally from remote coordinates [because we have to], and to study the Cosmological Universe because it encompasses everything.

13. ### eramSciengineerValued Senior Member

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1,877
I see that rr6 brought a few of his buddies along.

14. ### AlphaNumericFully ionizedRegistered Senior Member

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6,702
This thread is more than a decade old from its first post and the poster who bumped it from a 7 year old death didn't really need to do so. As such I'm splitting the relevant posts from the thread, which will drop back down into the depths of the archive, before possibly moving the new thread into the fringe section, once I've read the first post properly.

/edit

Okay, it's asking questions more than asserting ideas so it can stay for the time being at least.

15. ### AlphaNumericFully ionizedRegistered Senior Member

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6,702
That cannot happen. Energy isn't like a liquid you can squeeze out of objects like water from a sponge. It is an intrinsic property of objects, even when they aren't moving. Two electrons held a distance apart from one another will have energy due to their potential energy interactions, even if they are not moving. But that isn't possible either, since particles ALWAYS move, as I'll address now...

An object at 0K will still have moving particles. If they stopped they you'd be able to measure their positions and momenta so precisely you'd violate the uncertainty principle. At absolute zero particles still jitter about, just not as much as at higher temperatures. This is similar to the quantum vacuum not being empty, it always has matter and energy in it even if you remove everything you can, as particles flitter in an out of existence due to the uncertainty principle and the relativity relation $E^{2} = (mc^{2})^{2} + (pc)^{2}$.

The units of acceleration are not equal to the units of $c^{2}$, it is physically meaningless to say what you just said.

Something falling into a black hole will indeed increase the black hole's energy and mass yes.

You need to understand what the "Tying them together is hard" means. Quantum mechanics plus special relativity is already combined, it is called quantum field theory, developed from the 1930s onwards. It is the QFT stuff which models how mass and energy of particles relate, allowing them to convert into other particles or to appear and disappear via uncertainty. If you only consider a very small region of space, even near, on or inside an event horizon, then you can model the particles using standard QFT. What presents a problem is considering particles moving over non-tiny distances within a strong gravitational field, this requires tying together quantum mechanics and general relativity, which is the difficulty.

There are various partial solutions, semi-classical field theory for instance, which make some simplifying assumptions about the gravitational field, ignore a number of otherwise complicated processes and lead to things like Hawking radiation and black hole thermodynamics. Provided the gravitational field isn't too strong and the particles aren't too massive then semi-classical field theory is viable. It's when you get particles close to the Planck mass and/or particles within a few Planck lengths of the black hole singularity that it all goes to hell in a hand basket. It might sound counter intuitive but the event horizon itself isn't much of a problem, provided you're careful and you've formalised everything properly. Unless you have a micro-black hole of only a few Planck masses the event horizon is far enough away from the singularity that you can do semi-classical calculations and use current field theory models to describe particle dynamics. Once you're within a few Planck lengths of the singularity you can no longer ignore all of the quantum gravity corrections which semi-classical field theory throws away. Then you either need quantum gravity or you need to go home.

The Planck scale is, in a qualitative way, the distance at which gravity stops looking like Einstein's gravity and starts looking like quantum mechanics but in a way we currently do not understand. Provided you aren't considering Planck scale physics there isn't too much of an issue between quantum mechanics and relativity. Unfortunately Planck scale physics is where a lot of interesting cosmology and 'theory of everything' questions lie, since at some time in the past ALL of the universe was contained with the Planck scale.

16. ### brucepValued Senior Member

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4,098
RoccoR asks some good questions searching for some knowledge from the literature.

17. ### pluto2BannedValued Senior Member

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1,085
Black holes are a dream.

I think that general relativity is probably invalid because the properties of a black hole explained by general relativity would behave a lot differently. For example it is taught that upon reaching the event horizon, the 'object' is pulled inside the black hole but since time slows down the 'object' appears to be stuck on the event horizon. Light is trapped inside the black hole and should appear frozen in time on the event horizon. This is one of many observable properties of a black hole.

But an artificial electromagnetic black hole behaves alot like the black holes that we observe in the sky.

http://static.gamespot.com/uploads/scale_small/26/266400/2357090-2454131411-Black.gif

http://static.gamespot.com/uploads/scale_small/26/266400/2357097-5956460708-dn179.jpg

18. ### paddoboyValued Senior Member

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27,534

BHs are also predicted by Newtonian mechanics.
A fellow called John Mitchel in the late 1800s theorised the possible existance of BHs, which he called "Dark Stars", just by the application of mass, density, and escape velocity.

If GR BHs do not exist as you say, then you need to come up with some other solution to explain the observations that have been made that can only be attributed to something akin to a BH.

With your other statement re someone or something approaching the EH, he certainly will fall into the BH and meet up with the Singularity in a short but finite time.
But if you were watching from a safe distance, the gravitational effects of the BH will effect how you see your friend as he/she approaches the EH by the process of GRAVITATIONAL TIME DILATION...So much so that you will never see him/her cross the horizon, and your view will be continually red shifted along the spectrum until fading away altogether.

And of course we can never see a BH directly....that's why it is called black....no light is emitted, but we do and can infer their presence by their gravitational effects on objects and space/time around them.

19. ### paddoboyValued Senior Member

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27,534
Plus in addition to the above rundown, we do have Hawking Radiation, although as far as I know, that has yet to be detected.

20. ### paddoboyValued Senior Member

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27,534

We have plenty of evidence for BHs.
Unless of course you have a different model capable of producing the incredible effects we see and presently infer to as BHs.
I mean we actually have observed accretion disks spiralling in ever decreasing orbits inwards, at near "c" speeds giving off incredible temperatures, while being red shifted along the spectrum, and virtually disappearing into a central void.
Fairly convincing I would think.

21. ### KcoerRegistered Member

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1
Basically, we know black holes exists. Perhaps particles changes forms upon entry of the event horizon, one which acts differently than the normal elementary particles. Let's remember, energy makes up matter right? Energy can change forms - matter changes forms. Before a blackhole there was a quark star, before that a neutron star. Maybe their is a particle that makes up a quark that makes up the black hole. The fact is, their are thousands of possible theories of explaining this but none that explain all. Black holes are too far away to observe. Particles are similar to the black hole bolth are unexplainable. Bolth cannot be observed very deep.Lets focus on making telescopes and microscopes that can give a better view of bolth. Choosing or finding a super theorie is Above the technology of our time.

22. ### TrappedBannedBanned

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1,058
Though a lot of people simply believe there are no relationships between the quantum and gravity this isn't entirely true. Hawking radiation for instance, is an example where gravity and quantum mechanics are in fact unified; there is a quantum nature around these gravitationally massive bodies in the form of thermal radiation of the black hole.

Also, in my thread in which all the nonsense started, the metric of a Schwarzschild core can be written in terms of the energy contained in the metric. The gravitational field gives up this energy from a source to a detector. This is in fact analogous to the same description of Hawking Radiation. The only way it can give up this energy $\Delta E$ can only be in the form of quanta. So there is some understanding of the quantum relationship to that of gravity. There perhaps are even others.

23. ### brucepValued Senior Member

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4,098
I like Elle way to much to be dogging SETI. I like the effort which is certainly a worthwhile endeavor. Since you asked I'll provide a bit of information. The experimental effort to detect Hawking Radiation is ongoing. This particular experimental effort claims to have done so.

http://www.scientificamerican.com/article.cfm?id=hawking-radiation

I think this is the paper.

Experimental evidence of analogue Hawking radiation from ultrashort laser pulse filaments. E Rubino1, F Belgiorno2, S L Cacciatori1,3, M Clerici1,4, V Gorini1,3, G Ortenzi5, L Rizzi1, V G Sala1, M Kolesik6 and D Faccio1,7,8
http://iopscience.iop.org/1367-2630/13/8/085005/fulltext/
Or earlier submission.
http://arxiv.org/abs/1009.4634

This is why William Unruh doesn't agree with the conclusion that the radiation detected is Hawking.
Hawking radiation from "phase horizons" in laser filaments? W. G. Unruh, R. Schützhold
http://arxiv.org/abs/1202.6492

The experimental models are really interesting.