MigL

Tried to play chess with my cat once. Other than the crap all over the board, same result. Knocked all the pieces over and continuously licked my fingers when I tied to make a move.

The only reason you can call it negative energy is because it has to be paid back to the universe, according to conservation laws, at the end of e period of time dictated by the Heisenberg Uncertainty principle. You are using concepts you don't understand and drawing the wrong conclusions. Energy, wether negative or positive, has a mass ( remember E=MC^2 ??? ). Maybe you would like to give your definition of negative energy and how it differs from positive energy ??? Forget Susskind and re-read ( if you ever did ) Hawking on Hawking radiation. Maybe read it several times to be sure you understand it. Then come back and argue. Incidentally, if you are questioning the very existence of black holes, maybe you can tell us what magical device will keep a 4 solar mass stellar core from collapsing no farther than neutron star density. I know it can't be neutron degeneracy, so pray tell, what exactly stops the collapse ???

You keep picking and choosing statements from people's replies without reading their whole post. I have previously stated that Hawking radiation is due to a black hole's absorption of one half of a virtual particle pair, wether you choose to assign negative energy or positive energy to it. If you accept that Hawking radiation occurrs, you cannot maintain that black holes cannot injest mass because they will evaporate before that mass can cross the event horizon. EVAPORATION IS DUE TO MASS CROSSING THE EVENT HORIZON!!!

You're now spouting garbage as metre long waves have low enough energy to be localised at a much maller dimension according to Heisenberg's uncertainty principle. Do the math, then you can make such statements. A photon's wavelength is not linearly proportional to its size . By the way , the definition of frequency is repititions per second. An infinite wave cannot by definition repeat.

My point, slinkey, is that frequency and wavelength are inversely related , ie a zero frequency is equivalent to an infinite wavelength. When a photon's frqequency becomes zero at the event horizon, its wavelength becomes infinite, and it ceases to exist. Oh, and yes, a wavelength can be greater than its containment, it happens all the time at quantum mechanical levels and leads to what we call tunneling ( Please don't ask me if the infinite wavelength photon can then 'tunnel' out of our universe, because at infinite wavelength THERE IS NO MORE PHOTON ! ). Just a thought, do you think a photon's wavelength is related in any way to its size ( since you say an infinite wavelength means it is wider than the universe and so cannot cross the event horizon ) ???? If so, you really need to check your basic physics.

Check your basic physics, slinkey, a photon's energy is inversely proportional to its wavelength, so when the wavelength becomes infinite, its energy becomes undefined. Alternately, if infinities make you unconfortable, a photon's energy is proportional to its frequency, ie when it becomes zero, the photon has no enrgy. Negative and positive energy are just conventions which make the math more manageable. Read more advanced Hawking, rather than "A Brief History of Time" for a more complete explanation. Always keep the physics of the situation in mind, what exactly would be the properties of 'negative' energy ?? I'm at work, will try to get back later for more discussion.

Alan2here, there are numerous books that describe black hole formation due to stellar collapse. Radiation pressure constantly fights gravitational collapse in large objects like stars. When nuclear reactions no longer supply the outward radiation pressure because the stellar core has become iron, the star, or more specifically the core will collapse. If the star/core is smallish it will collapse until electron degeneracy ( Pauli exclusion principle for occupation of Quantum States ) starts pushing back and halts the collapse. These are known as white dwarf stars. Larger stars won't be stopped by electron degeneracy, but will actually force electrons to combine with protons to form neutrons, until the whole core is mostly neutronium and neutron degeneracy stops the collapse. these are known as neutron stars or pulsars. Even larger stars' cores won't stop at solid neutrons, as a matter of fact we know of no force which can stop the collapse if the core is of a certain size. Even if they blow away most of the mass in a supernova explosion. These are known as black holes.

It is not a question of wether an egg can be unsrambled, That is an entropy question, and yes entropy can decrease locally. In effect there is a small possibility that the egg will unsramble. It is very small because of the statistical mature of macroscpic objects like eggs, but it can be large for non-statistical, sinle microscopic object. Atomic interactions will look perfectly normal wether the film runs foreward or backwards. Causality violation is more subtle. You cannot scramble an egg without first breaking it, beating it, and cooking it, ie the breaking/beating/cooking are the causes that enable the scrambling effect to happen. Causality violation would permit the egg to scramble BEFORE breaking/beating/cooking. Just like in my previous example where the writing appears in the book BEFORE having gone into the past to write it.

Alan2here, your argument/assumptions have more holes than swiss cheese. Slinkey, your argument ultimately reduces to "black holes cannot exist", since they cannot even ingest the original mass/energy that creates them. If you would like to argue THAT point, I've gotta warn you, I have GR on my side, and helping me with my argument will be Einstein, Swartzchild, Oppenheimer, Wheeler, Kerr, Penrose, Thorne and Hawking. Who's on your side ??

Why is it reasonable to asume that space is an empty volume ??? Maybe 'ontology' cannot explain virtual pair creation and all the effects attributed to this phenonenon, but GR/QM can. There is an energy associated with 'empty' space/time. This energy accounts for various effects ( such as the above pair creation and Casimir effect ) and predictions which are still being worked on ( possibly even the origin of the universe and its expansion ). So yes space/time is an entity, and it has many measurable quantities. Because philosophy and ontology do not bother with measurable quantities and experiment doesn't mean space/time is not an 'entity'.

Don't understand your objection to the fact that an infinitely red shifted photon has zero energy, and since energy cannot be destroyed it must end up as added energy ( mass ) to the black hole. Maybe I wasn't too clear in my explanation, or maybe you mis-read. Don't follow your reasoning that "a photon reaches an infinitely long wavelength then can it be said to actually exist?" What does that mean? An existing photon is red-shifted to infinity and CEASES to exist, so the energy/mass must go to the black hole! Also I only used a photon to make the argument more manageable, but feel free to use an astronaut or a spaceship, they will both 'loose' their mass/energy at the event horizon, and it will have to go to the black hole since a black hole is the ultimate information shredder. Incidentally thesame but reverse argument is responsible for evaporation ( Hawking radiation ). If mass/energy 'appears' next to an event horizon due to virtual particles, then even though the black hole absorbs one of the pair, it must repay the debt to the universe and LOOSES mass/energy ( instead of gaining ).

Oh, good greif, owl. I didn't realise there was an ontological interpretation of time as well as space. Just kidding. Most physicists will agree with you. It is always now, everywhere. But will add, thogh not necessarily the same now. Say you have a time machne and a notebook. Next week you will travel two weeks into the past, at which time you will write in the notebook "it worked!". If you open the notebook now, are the words "it worked!" written in it or not ??? What I'm getting at, is could there be a law which we haven't formally expressed yet which forbids this ? Hawking has put foreward a law which forbids time travel ( I forget its proper mame ). It seems that if time travel were possible in the case presented above, causality would be violated, ie. something would happen which hasn't been caused yet. Could there be a law that forbids causality violation ?? HOWEVER! Causality seems to be violated often in Quantum Mechanics. Take an electron beam passing through a single slit. It will give the classic single slit diffraction pattern. Now take the same beam and pass it through two slits and you get the classic two slit diffraction pattern. Now if you reduce the beam to a single electron and pass it through the two slits, obviously it can only pass through one of the slits, yet the same two slit diffraction pattern results. How does the electron know that another slit is open, unless it actually passes through both, then goes back and chooses the path of least action ?

I will try this again. Let's not consider an infalling astronaut, into a black hole. Let's consider a photon of visible light, with a given amount of energy, approaching the event horizon. Now we all agree that as it approaches the event horizon, it approaches a deep gravity well, and so time slows down. Time will eventually slow to zero at the event horizon so some members assume that since time is at a standstill, the photon cannot actually cross the event horizon. This logic is flawed. We don't actually 'see' the photon slow down, what we see is a lengthening of the photon's wavelength, which tends to infinity at the event horizon. Now one important property of a photon with infinite wavelength is zero energy, ie the photon ceases to exist, since the photon, before it began its journey towards the black hole had an energy inversely proportional to its wavelength. According to the law of conservation of mass/energy, the energy of the photon cannot simply disappear. It has to go somewhere, so the black hole gains the equivalent mass of the photon's energy. In effect THE PHOTON HAS CROSSED THE EVENT HORIZON INTO THE BLACK HOLE. I don't know how some people got the idea that things falling into a black hole stop at the event horizon, but that is not the case. If it were true, it would be impossible for a black hole to form ( think about it ) and this whole argument would be moot. To recap. Things do fall into black holes. Primordial microscopic black holes ( left-overs from the big bang ) do evaporate and probably did so a long time ago or else we would see extreme flashes of gamma rays when their mass becomes less than critical and they explode. Massive black holes, formed from collapsing stars do evaporate, but they continuously ingest more mass than the evaporated amount and so gain mass, not loose it, so in effect they will never evaporate enough to explode and re-enter our space/time ( that may even violate the second law of thermodynamics as entropy would decrease on a very large scale ).

My apologies, owl, I assumed a spelling mistake where there was none. I was ( always seem to be ) in a bit of a hurry. My only point was that extra dimensions are a useful tool, whether real or imagined. If they have predictive effects then they may as well be real. There are a lot of things which cannot be seen or proved directly, only by their effects ( black holes, dark matter, sub-atomic particles, radiation, even air ). Yet I'm sure you have no problem accepting them.

I'll repeat, the distant observer sees the light coming out of the gravitational well more and more red-dhifted, until it finally disappears. But the infalling astronaut falls at the acceleration due to gravity just like anywhere else. He may see the 'end' of time when looking back out of the event horizon but the ONLY thing in his future is the ( possible ) singularity.

You want real references ? Very well. Look up quasi-crystals. You will find that their crystalline structure is not regular at all like all other crystals. However it turns out their structure is a projection ( which see ) of a 5-dimensional structure, ie their structure is only regular in FIVE dimensions. You are confused as to the meaning of dimensions in physics. For the mathematical meaning DrR has already explaned several times but in physics an extra dimension is not another direction beyond the known three, but another degree of freedom. In effect another 'way' to estabilish a relation. Take for example Siberian Mongol peoples and North American Inuit people, how are the two rlated ? We can establish a connection between the two only by considering another dimension. We realise that the dimension of time estabilishes a connection between the two about 15000 yrs ago ( the Bearing Strait land bridge ). This is the 'real',' physical' meaning of extra dimensions, you should try to wrap you head around it as a curved space/time is not a big stretch from these examples. We build models of reality using mathematical tools such as extra dimensions. Sometimes these dimensions are so small ( 10^-33 ) and compact ( ie curve in on themselves like a straw ) and two gentlemen named Kaluza and Klein managed to use this ffth compacted dimension to relate and unite Maxwell's theory of electomagnetism with Einstein's general relativity. Current string theories involve 10 or 11 dimensions to relate and unify all four known forces.

Don't take pieces of my reply and use them to incorrectly justify your ignorance. Things do fall into black holes and the evaporation time for black holes is possibly infinite for anything other than microscopic primordial black holes. Read some Hawking for a clear explanation of BH evaporation.

Take the case of two astronauts, one a distant observer to a black hole and the other unfortunate one falling into the black hole. There has been a suggestion that the distant observer never actually sees the unfortunate astronaut fall through the event horizon because time slows to zero and he will first see the evaporation of the black hole. As the unfortunate astronaut falls nearer the event horizon the distant observer will see time slow, but he will also see a stretching of the visible wavelengths, ie. his image of the infalling astronaut will become redder and redder until it goes to infrared, then microwaves, long radio waves and finally stretched to infinity at the event horizon. The light has lost all its energy and since you cannot destroy mass/energy, it must have been 'absorbed' by the black hole. So, yes, things actually do fall into a black hole, even to an outside observer. From the infalling astronauts point of view, the question is moot. Time does not slow down for him and he crosses the event horizon at which point the only thing in his future is the ( possible ) singularity. A black hole's evaporation is a quantum mechanical phenomena, having to do with virtual particle creation. The infalling astronaut and observer is a GR phenomena. Don't mix up the two. You are trying to use the two models at boundary ponts where one result may not agree with the other.

Owl, you're getting hung up on definitions and misunderstandings. One typical one that you posted: "So "closed" in this context has a special, counter- intuitive meaning. One usually thinks of closed as having an inside and an outside, and in the context of this thread, the space outside of a closed cosmos (I will not say "universe" in this context) has no end or boundary, so is therefore infinite. " No! The manifold is the cosmos, or universe, and it is closed or compact because it curves back on itself. It is not the inside ( or outside ) of the manifold. The inside or the outside, are inconsequential and have no meaning. Why are you trying to give them a meaning? You seem well read on the philosophical implications of the finite and infinite. Maybe you should read an elementary text on topology, or even a popularization. I seem to remember a book called The Poincaire Conjecture which did an adequate job of describing higher dimensional curved spaces. I think you would then comprehend the meaning of finite but unbounded manifolds.

The fact that you find something absurd, or that Hawking said it, is not a valid argument against the existence fo higher dimensional topology. Otherwise you could disprove all of Quantum Mechanics.

Owl, it seems like your objection to a finite but unbounded universe is due to the fact that there must still be an outside to it, since it needs to curve in on itself in another volume. Let me see if I can help clear up some confusion. If we again consider the two dimensional, positive curvature surface of a sphere, I think we can both agree that even though two dimensional, it must curve in a higher dimension ( the third ) to reconnect to itself. Similarily a three dimensional volume can also curve back in on itself and be bounded, but it must do so in a higher dimension, ie a fourth. Now don't confuse this fourth dimension with time, GR says 3-d space may curve back on itself, but not time. or as DrR like to say the foliation may fold back on itself to 'unbound' the universe. You prefer infinite space with no bounds, ie flat euclidian space. You are giving a significance to this higher dimension through which the 3-d space is curving where there is none. Assume the two dimensional, flat ( euclidian ) space with no bounds analogy that you seem to prefer to the curved sphere, in higher dimensions there is also an 'above' and 'below' the euclidian plane. You don't seem to have an objection to this, why do you have one with the outside and inside of a sphere. Again there is no significance to either. I don't know if I've been very clear and that's why DrR likes to use the appropriate language, mathematics. The point is that your main objection, that there is an outside, is always there, whether dealing with 'flat' space or positive or negative curvature space. This outside is only in a higher dimension though and as such, is inconsequential.

The horizon is the same for any kind of energy as it all travels at c, and the universe is expanding, ie at acertain distance all energies are red-shifted to infinite wavelength and zero energy. This makes the observable universe a finite size no matter which energy wavelength you use to 'observe'. The CMB permeates all of the universe, it doesn't exist only at the horizon. If you could measure the CMB right beside you, it would be 2.7 deg., not just at extreme extragalctic distances. I hope I'm not misunderstanding your original query. If I'm not you haven't grasped the significance and explanation for the CMB.

The cosmic microwave background radiation arises from the 'decoupling' of radiation from matter. It is the point in time ( approx 300000 yrs after big bang ) when the temperature of the universe had dropped enough for stable atoms to form, ie electrons captive to atoms of hydrogen, helium and lithium. Previous to this, electrons were free of the ionic plasma which composed the universe because as soon as an electron tried to attach to an ion, it would be knocked lose by an energetic photon, much like the interior of the sun, and so the universe was opaque. Neutrinos decoupled a lot earlier and since neutrinos are extremely difficult to detect, the red shifted neutrinos from the decoupling era would be impossible to detect. Gravitons would have decoupled at 10^-34 sec after the big bang, the end of quantum gravity, and we haven't even detected normal gravitons yet, never mind low energy ones from such an early time.

During QM's formative years there was some attempt at making it more common sensical. I believe it was originally de Broglie' s idea to introduce a pilot wave to particle motion in an effort to explain the differences between the double slit diffraction of an electron and the single slit diffraction, and how does a single electron know if the second slit is open or closed. This was during the time of Einstein's famous 'challenges' to Bohr's stochastic interpretation of QM. The pilot wave was later re-introduced by Bohom ( I don't know if that's the correct spelling ) in the 50s, but because of his history as a communist he was forced to leave the country to work in Brazil ( yes, that sort of thing did happen in the 50s ). The latest questioning of QMs interpretation was by Bell in the 80s who obtained a probability of an event happening more often than always ( non-sensical ). So maybe there are some hidden variables which haven't been considered in our formilation of QM and which may eventually move us away from a probabilistic interpretation towards a deterministic interpretation in which reality and causality are front and centre. Don't get me wrong, I've known QM for 30 yrs and as a theory it has made thousands if not millions of accurate predictions to as many decimal places as required, so it certainly does work. If it turns out to be the equivalent of Newton's gravitation, ie. not complete as compared to Einstein's gravitation, don't forget that we can still get to the moon using Newton's theory and its all we need for most problems.

You guys are confusing wave-particle duality with Quantum mechanics. Wave-particle duality has been around since the time of Newton and Hyugens, way before QM was a twinkle in Max Planck's eye. The model we use to explain phenomena and make predictions about a system is tailored to particular aspects of the system but not necessarily to all. As an example, try to explain the double slit diffraction experiment with the particle (photon ) model of light. Or try to explain the photoelectric effect with the EM wave model of light. You cannot do either. However particulate photons easily explain the photoelectric effect and diffraction is easily handled by the wave model. Use the model appropriate to the circumstances, since a photon, in reality, may be neither a wave or a particle ( it may be a certain harmonic of a vibration of a 10^-34m segment of space/time, otherwise known as a string, another model ).