Discussion in 'Physics & Math' started by rohIT, Nov 21, 2012.
Maybe you should research the literature.
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Thanks for that honest and thought out reply, Billy T. Much appreciate the time and trouble you took.
I agree that the explanation as to exactly how and where etc etc the energy of the bh interior is 'physically reduced' is still unclear/unavailable from the literature.
I have taken your comments/info on board and will await other replies and see what comes out in the wash about this aspect. Thanks again. Cheers.
Thanks for your reply, brucep. Much appreciated.
Hmmm. That 'explanation' assumes that the g-field 'energy' is part of the total bh energy, does it not?
If so, and if the energy is, as posited above, "taken from the g-field energy", then the energy of the g-field is what is affected, not the bh interior mass itself which GENERATES that field.
Which raises another question: How does reducing the g-field 'feed back' to the g-field-generating energy-mass 'feature' in the first place?
It's that sort of logically-implied 'feedback' effect in order to explain the energy-reduction of the bh interior 'feature' itself that I want more actual PHYSICAL consistent 'takes' or explanation about?
Any further takes or info would be greatly appreciated, brucep (and anyone).
Thanks again for your trouble and info. Back later if I can. Cheers!
A general observation regarding micro bh supposedly becoming/radiating 'white hot'.
How is that even possible, considering that any photon or other OUTGOING 'wavelength' feature would be EXTREMALLY REDSHIFTED climbing away from such an extreme g-field gradient, such that the now supposedly 'real' photon would lose most of its energy before going any significant distance at all. If so, and that energy is then effectively 'given back' to the g-field itself thereby, then it is difficult for me to see how anyone can use the term "white hot' to describe the event horizon surface/region, UNLESS there is another mechanism for photons leaving to NOT lose most of their energy to extreme redshift/gravity again?
Any comments/info on this question observation would also be much appreciated. Back later if I can!
Same ol illiterate bs from you. What I wrote down is supported by physics. It describes what's happening from both local measurements and remote measurements. For 'all you cranks' that's the crux of the situation. You don't understand or want to understand the literature.
Nevertheless, some clarification by you regarding exactly and specifically what, where and how you think those 'descriptions supported by physics' actually 'physically explain' those things which I specifically pointed to and queried about there would be very much appreciated.
Particles quantum tunnel out of the black hole horizon, which is nothing more than a finite potential barrier with a classical energy limit.
Thanks for your interest and link prometheus.
I was already well aware of that, which is why I have these other questions as in my second last post above.
You see, even allowing that quantum tunneling is actually what occurs from bh event horizon proximity, I am left wondering why Neutron stars and gravastars and such extreme gradient features do not also 'radiate' white hot? Would similar quantum effects like vacuum fluctuations and particle pair production and quantum tunneling from within their own extreme gravity well also result in a certain 'quantum effects' radiation from them? Would they too appear "white hot" if the photons leaving their lowest gravity level positions also tunnel out' and not lose any energy via redshift as posited for bh event horizon gravity levels case?
I suppose there must be something which would allow such 'tunneling' away from bh but not from these other extreme feature surfaces? If so, I can't find it in the literature 'specifically' covering that 'comparative' case for the "tunneling" process per se.
Thanks again. Back later!
I used the term "white hot" here:
And clearly am speaking of "surface temperature at the event horizon " as I stated, not the color temperature seen from great distance after red shift. I think any temperature greater than twice solar (~12E3 K or C) can be called "white hot" but this is many orders of magnitude less than Hawkings spoke of for even last hour of a BH. In the final fraction of a second I think the peak of the black body spectrum radiated is harsh Gama rays. Then even the full red shift from the then SMALLER black hole, I guess, would only get them down to X-ray wave lengths! (Far beyond "white hot" temperatures).
Thanks for that clarification, Billy T. Lucky I caught you before logging out!
What about the "tunneling" aspect I queried in my reply to prometheus? Can you or anyone shed light on whether "tunneling" also occurs away from extreme surface gravity from Neutron Stars and Gravastars?
Back tomorrow. Thanks again, everyone!
I've never seen that. That derivation is right in my wheelhouse. All measurements are made in the local proper frame of an object falling into the Schwarzschild black hole. They extend the metric to include the component of charge. Can this metric be further extended to include the rotation parameter?
I am somewhat mystified by all this talk of tunneling thru the event horizion as it is only a mathematical surface. Locally, not only is there nothing there, but there is not even a local discontinuity in the gravity field either - it is just smoothly falling as the inverse square at the EV or at the (EV + a Km) or at the (EV - a Km) surfaces too.
However, at the surface of a neutron star there is a real discontinuity - the material density goes from unimaginable high to essentially zero in much less than a mm! Locally the surface is extremely smooth - biggest bump is less than a micron high! But all except the very old ones are spinning so surface is not exactly a sphere.
At the physical surface of a neutron star, the gravity is most intense - moving either outward or inward makes a REDUCTION in the g-field strength - hardly what can be called a potential well, so I´m not sure "tunneling" makes any sense there either but the nuclear forces may well have a step function there, so when they are considered, perhaps tunneling does make sense, but I would tend to speak of QM assisted "evaporation" instead of tunneling.
The reason you're mystified is the physics is beyond you. What you think makes sense is irrelevant.
Yep, sure can, there are a number of papers that cite Wilczek and Parikh that generalise the technique to all sorts of black holes, and other spacetimes where particle creation can happen like de Sitter space (disclaimer - I've not read that paper. It it turns out to be rubbish don't blame me).
You're getting confused between density and potential. I can't remember if they do it in the paper I linked to, but if you take the equations of motion for the black hole it's a straight forward exercise to use them to form an equation for the energy of the system and then extract the potential. You will then see that there is a peak at r = 2M, and the height of that peak exactly corresponds to the maximum allowed energy of the system so particles can never have enough energy classically to get out of the BH, although they can quantum tunnel, as in the most basic potential barrier example. You are the one talking about neutron stars, so you can call it whatever you like I guess. Whether tunnelling can contribute to the loss of mass from neutron stars is something I don't know, and I'm not sure is known. Do neutron stars evaporate at all?
I´m not confused between density and potential, but just ignorant about BHs. You seem to be telling me that the gravitational potential (with zero level defined far from the BH) decreases (as is going negative) as inverse R, but as one gets close to r= 2M it has some other form, equation, so that it is most negative at r =2M and then becomes less negative for r < 2M all the way to the singularity at r = 0.
Is that what you are stating or am I misunderstanding (put words in your mouth)? If that is both what you are stating AND true, then I agree there is a gravitational potential well at r =2M which particels might "tunnel out of" despite lack of energy needed to escape, but why do they not just fall back into the well ? This would seem to be a very different concept about the mass distribution of a BH from any I have ever heard of as it implies the mass is found in a shell of radius r =2M.
Question (1): Where do you think the mass of a Black Hole is located? - At this spherical (for non-spinning BHs) shell or at (or very near) r = 0, which is the common POV. (I assume you do think that any free to move mass ALWAYS falls toward the most negative gravitational potential place it can.)
Question (2): If you don´t accept the common view that the gravitation potential goes as inverse r down to at least very near r = 0, how does it go?
I admit to a very strange, perhaps unique, POV. I.e. Because I think singularities are only mathematical artifacts and don´t really exist, I think there is a currently unknown "fifth force" which is however repulsive (not attractive) but is otherwise somewhat like the strong and weak forces in that it is appreciable / detectable from any atomic matter only at very short ranges. It could, however, be significant even at long ranges when summed up from all the matter of the universe as perhaps there is a non-zero minimum, which is a range independent level, and extremely weak so not detectable even at the solar surface. - I.e. such a "fifth force" could be the basis for "dark energy" and the accelerating expansion of the universe.
My dislike of singularities is why I postulate this fifth force: In my simple minded, ignorant POV, I think the gravitational potential does go to minus infinity as r approaches zero and that of course would make the point singularity that many think is a BH, but it does so only as inverse r. The postulated repulsive fifth force has a more exponential dependency upon distance (except for a possible extremely weak constant, if one wants to use it to explain dark energy). Exponentials always dominate inverse r laws so the BH in my ill-defined "fifth force theory" has a finite non-zero radius - no singularity.
Again, please answer questions (1) & (2) above and don´t hesitate out of kindness to tell why you think my "theory" of BHs is BS.
On neutron stars I also know very little, certainly not anything about potential loss of mass from them by any process that could be called "evaporating," but they do seem to have some quantum levels when seen as very precise clocks. When these cosmic clocks were first noticed years ago by a lady physic graduate student she called them LGMs (for Little Green Men) who had made these very precise cosmic clocks for some unknown reason.* Only some years later were they associated with spinning neutron stars. Of courses, once one LGM was known, many others were quickly found and monitored. They are very good clocks - at least as good as man-made atomic clocks (or better?) but do have a defect as clocks: every few years (I think) they abruptly increase their "tick rate." This is now thought to be some abrupt slight partial collapse, which decreases their radius so conservation of angular momentum increases their spin and tick rate.
*Possibly their "GPS" for navigation thru out the universe, but she made no such suggestion as GPS had not yet been invented. (I worked slightly on the Navy´s navigation system that preceded GPS. It only required one satellite, not three, in a well-known low orbit. Where you are can be computed from the observed Doppler shift of the broadcast frequency as the satellite passes over. If it goes directly over head the Doppler shift is greatest and less for non-over-head passes. This system, curve fitting to several minutes of Doppler data, was invented at APL by two men who recorded the broad cast from Sputnik, and knowing where they were, computed the orbit of Sputnik as accurately as any other method available. They almost immediately realized that their computation could be inverted if the orbit were known to find out exactly where you were and sold the idea to the Navy, which did not want to expose its nuclear subs on the surface to the USSR´s satellites to get good location data from the stars. - To hit Moscow with an ICBM from a sub at sea, you must know very accurately where you launch from. GPS, with several higher altitude satellites can give you your locations all the time anywhere and this Doppler shift system, with even more lower altitude satellites (for big Doppler shift) only works when a satellite is visible for several minutes. GPS is one of the many benefits that historically have come from man´s destructive war efforts. Another problem with the Doppler system is that the low satellite orbit parameters must be measured every week or so and up loaded into the satellite as residual air drag is constantly changing the orbit. Navy needed to know very accurately where its sub launched from as any error accumulates rapidly during fly out to target in large part because the Earth´s gravitational field is far from spherical - APL measured it for the Navy -the harmonic expansion coefficients but how many and certainly the values after the first dozen or so is still highly classified, I think. China surely has a good model of Earth´s gravity field too. They don´t want to vaporize Hoboken, NJ when the target was NYC.)
It's a coordinate singularity. It's not just a math construct. Regardless the metric solution being used the fact remains no information can be sent from inside, r<2M, to outside, r>2M. The metric, Prom linked, used to evaluate the tunneling mechanism is a local proper frame metric. Measurements made in the local proper frame of the observer falling into the black hole can't be sent to observers outside the black hole. It's easy to understand the consequences of a coordinate singularity at r=2M but not easy to understand the real singularity at r=0. That is the domain of quantum gravity.
Thanks Prom. The papers are wonderful. Great for my favorite interests. As you know there is no mechanism for neutron stars to evaporate. They shed J/M as they brake over time . The total mass is M + J/M.
If you agree that it is incorrect to speak of energy being "borrowed", how do you account for the violation of the conservation laws you claim?
A virtual particle does not precisely obey the formula m²c⁴ = E² − p²c². In other words, its kinetic energy may not have the usual relationship to velocity–indeed, it can be negative.
...They are "temporary" in the sense that they appear in calculations, but are not detected as single particles. Thus, in mathematical terms, they never appear as indices to the scattering matrix, which is to say, they never appear as the observable inputs and outputs of the physical process being modelled. -wiki
So what other virtual particles are there? While perhaps not an optimal description, we can very well describe the Casimir effect in terms of virtual particles.
You've linked some great literature. Especially the Hawking discussion. Thanks. Negative energy does exist as real natural phenomena. I'll link Project F The Spinning Black Hole. Starting on Pg F-21 begins the discussion on negative energy and the region of the spinning black hole where the stones total energy can be negative. It's also a discussion on The Penrose Process. There's a nice diagram for those who like pictures [me included].
Project F from Taylor and Wheeler Exploring Black Holes.
As you know the energy density between the Casimir Plates is negative. For those of you who think negative energy can't exist as real natural phenomena.
Zero-point-energy (or ZPF of vacuum energy), is most commonly discussed and explored in the electromagnetic spectrum.., as a ground state EM radiation or vitural photons. Theoretically there should be analogues to the EM spectrum for both the strong and weak nuclear forces. I have seen little real work in those areas. When addressed within QED it is composed of virtual photons in a range of wavelengths. When addressed from the context of SED the virtual photons are treated as real.
The ZPF of vacuum energy is supported by experimental confirmation of the Casimir effect. This is an indirect confirmation of zero-point-energy, since it is only a predicted effect that is confirmed, not a direct observation of a ground state EM field. I have read one paper that claims to have directly observed real photons emerging from the Dynamical Casimir effect...
Most of what is being discussed in this thread are the virtual particles that fill in the gaps in high energy particle transitions. These have not been measured or observed. They at present remain artifacts of the theory and mathematics involved, time will tell whether they are an accurate description of was is actually happening. All we currently seem to have, is what we begin with and what we end up with, and a theoretical model that suggests that during the transition, unobserved virtual particles must be involved.
Billy T gave a reasonable and simple description of the mechanism involved in the Casimir effect back in post #4.
If you assume that that EM radiation carries momentum, you can think of the Casimir effect as the result of a difference in the momentum potential of the vacuum energy between two uncharged conductive plates as opposed to that outside the gap between the plates. Though it is often described as an attractive force, it is the greater momentum potential of vacuum energy preassure outside relative to between the plates, that pushes the plates together. The Casimir effect is an electromagnetic interaction between matter and the ground state magnetic field of zero-point-energy. The gap between closely placed plates limiting the EM field between the plates results in a reduced interaction and potential transfer of momentum, as compared to the external surfaces of the plates. It involves virtual photons (QED) or real photons (SED).
The Energetic Vacuum: Implications For Energy Research, Puthoff (1988)
An elegant analysis by Milonni, et al., at Los*Alamos National Laboratory shows that the Casimir force is due to radiation pressure from the*background electromagnetic zero-point energy which has become unbalanced due to the presence of the plates, and which results in the plates being pushed together.
See also a later paper by Milonni, Casimir forces, Milonni 1992.
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