h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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This is one of those ideas I came up with a couple decades ago. I'm not sure why I never posted it here before. Possibly I saw something similar enough to think that it couldn't meet the originality criterion. Or perhaps I did sort-of post it in an annotation somewhere. But I no longer recall what
that was, and besides, I could actually have been first to originate it. So, here goes...
The notion itself is pretty simple; just obtain a very small Black Hole, and shovel matter into it, exactly as fast as the thing tries to disappear via Hawking Radiation. We filter out all such "radiation" that cannot annihilate into gamma rays, and send the filtered particles back into the Black Hole. We use the gamma rays as an energy source (to boil water to make steam to power turbine/generators, for example).
Now I get to explain that in detail :)
Not too long after the fairly well-known physicist Stephen Hawking used Quantum Mechanics to show how it is possible for a Black Hole to "evaporate", that's when I thought of this Idea. Late 1970s, if I recall right. Here's how the evaporation process works:
First, a perfect vacuum is not really empty. I've discussed this before in my "Faster Than Light" Idea, so I'll just link to that and proceed. Just remember that when "virtual particles" pop into existence from Nothing, they are allowed, at the moment of their popping, to possess pretty extreme amounts of energy.
Next, while all the mass of a black hole is described as having collapsed (or is forever collapsing) into a mathematical point, the thing still has a kind of "surface". Known as the "event horizon", this is a non-physical thing, and it is nothing more than all the mathematical points which are located at a particular distance from the center of the black hole. (I assume a non-rotating black hole here; the shape of the event horizon is a perfect sphere in that case. The event horizon of a rotating black hole will be an "oblate spheroid"; maybe I can find a link for that.)
Next, the size of the spheroidial event horizon is directly related to the mass of the black hole. A hole that has the mass of the Sun will have an event horizon of less than twenty kilometers in diameter. If the hole had the mass of the Earth, it might be bacterium-sized. I almost forgot to mention: The event horizon is that place where, **IF** you could stand on it, you would have to travel exactly at the speed of light, to be able to escape the Force of Gravity of the black hole.
And now we get to see what Hawking first saw, when he thought about the event horizon interacting with virtual particles in the vacuum. The key point is that popping virtual particles exist on BORROWED energy, courtesy of the Uncertainty Principle. They have to pay that "borrowing" back, and when they do, they disappear back into Nothing.
But WHILE virtual particles exist (usually for a tiny fraction of a second only), they are real enough to be affected by such things as Gravity. So, suppose a pair of particles pop (they always pop in pairs) right AT the event horizon of a black hole? They will probably fall in, of course. (They will STILL disappear, to pay back their borrowing.)
BUT -- remember that when they pop, they can initially possess very large amounts of energy. The pair of particles also tends to zoom away from each other. In random opposite directions, of course. So, this means that if a just-popped pair happens to be oriented such that one zooms exactly toward the event horizon, then the other will be zooming exactly away -- and it will be energetic enough that it could be travelling at nearly light-speed.
This means the black hole can in this case swallow one of the particles, but the other can get away! It ALSO means something unique: That borrowed-energy which-must-be-paid-back must be paid back by the black hole! It LOSES an amount of mass equal to the particle that escapes!
Now here are the fun parts: (1) those pairs of virtual particles that pop into temporary existence tend to be one matter-particle and one anti-matter-particle -- for example, an electron/positron pair. (2) The particles that escape the black hole will RANDOMLY be either matter or anti-matter. (3) The smaller the black hole, the easier it is for particles to escape -- a small-enough black hole will positively GLOW with radiated particles, and will actually quickly die, utterly, in a rather significant explosion (a nice large number of megatons).
Obviously, therefore, this is going to be one risky and dangerous Idea. But hey, Space is vast and has plenty of room for widely separated (automated!) power plants and the occasional large explosion.
So, like I first said, we obtain a nice small black hole that is radiating fiercely, but not yet quite small enough to explode. (Yes, I know we might have to make one, if we can't find any still hanging around from when they might have formed during the Big Bang.) We aim some particle-beam devices at the hole, so we can inject matter into it (say a proton beam and an electron beam, to maintain a balanced total Electric Charge). From its radiance we can compute exactly how much mass the hole is losing each second, so all we have to do is beam/inject/replace that mass at the same rate.
Next, we use magnetic fields to capture the particles that are radiating away from the tiny black hole. As already mentioned, about half will be matter and half will be anti-matter. We make sure these particles meet and annihilate each other, producing gamma rays (or we add them to the feed-beams, and dump them back into the black hole). Thus do we acquire an energy source for as long as we can find ORDINARY matter in the Universe, to be converted via the operation of the black hole, into pure energy....
Faster Than Light
Faster_20Than_20Light
About those virtual particles in the vacuum... [Vernon, Dec 24 2004]
Oblate Spheroid
http://mathworld.wo...OblateSpheroid.html
Spheres that spin fast enough tend to look like this. See Jupiter and Saturn, for example. [Vernon, Dec 24 2004]
Wikipedia article
http://en.wikipedia...ki/Total_conversion
Before anyone claims that the above is not original with me, **I** was the one who put the black hole stuff into that article! (of course, being a Wiki, it might not still be there when you go look at it, but that's the breaks :) [Vernon, Dec 24 2004]
Black holes and electric charges
http://groups-beta....bb#cdeac6b9799412bb
[5th Earth], don't bet on it! [Vernon, Dec 24 2004]
[link]
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Vernon, it's 24 hrs before C. time. Everyone is on their best behavior sucking up to somebody right now so that they get their presents. I'm not one of them but I'm still not going to read anything with such a boring title. |
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Heh, actually I think that if you read enough science fiction, you will find that "total conversion" is a pretty standard name for the (typically hypothetical) process of converting 100% of ordinary matter into useful energy, WITHOUT starting with an equal amount of anti-matter. The first reference I can think of was in Robert A. Heinlein's story "Universe", written about 1941. (And while the Idea here does involve anti-matter, that's only because the black hole in-a-way makes it for us from ordinary matter.) |
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So really this is a proposal to use a black hole as an energy source (not a new idea) and to prevent it from catasprohpically evaporating by periodically "feeding" it (which is a new idea). |
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Well... it's scientifically valid. But I'm just not very impressed--it's a minor addition to the idea of black-hole power. |
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Incidentally, refilling it with just protons or electrons might be a GOOD thing--an electrically charged black hole is much easier to handle than a neutral one. |
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[5th Earth] be careful about how you say that black holes have been proposed before as energy sources. The mere process of dumping mass into them can convert up to 40% of the dumped mass into energy right then and there. In Nature, "accretion disks" around black holes are thought to be the energy source of quasars. So, can you find a link to a prior proposal to specifically use Hawking Radiation as the energy source, instead of accretion? |
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"...an electrically charged black hole is much easier to handle than a neutral one." |
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Based, no doubt, on extensive personal experience. |
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The theory of it appeals --- but I have to question what the theory relates to in practice. |
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Is a black hole a mathematical point -- no. |
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So what form does it take? It is most likely that it is larger than its event horizon and so the radiation theory is infeasible, i.e. there is no matter dense enough to form a black hole existing within its own event horizon. |
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This leads directly to the relationship between energy(matter) and space(volume) --- something like an "idea gas" equation. |
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Forgive me if I missunderstand you madness, but I think you have it all wrong. The black hole itself is a point mass, and the event horizon covers it. |
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The only effects outside the horizon are gravitational. |
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[bristolz], actually, while I personally doubt that a black hole can exhibit an electric charge, IF it could, then a small charged black hole really would be easier to manipulate than an uncharged hole. We are very good at using electromagnetic forces to manipulate charged particles. |
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[madness], you took the phrase "mathematical point" out of context. We know of nothing that would prevent the MASS of a large black hole from collapsing under Gravity into a mathematical point. --OK, well, maybe just ONE possibility. The Exclusion Principle of Quantum Mechanics prevents two "fermions" from having identical properties, such that they cannot occupy the same place at the same time. That's why neutron stars and even (somewhat hypothetical) quark stars are stable. But (1) the Exclusion Principle has its limits, and (2) two fermions can interact to form a "boson", and bosons CAN occupy the same space at the same time! And so a massive enough object will indeed collapse to within the event horizon. |
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Next, the ultimate collapsing of matter does not really affect the at-a-distance gravitational properties of the object very much. For example, if you could stand on the surface of the Sun, about 700,000 kilometers from its center, you would experience something like 27 times the gravity of Earth. If the Sun was replaced by a black hole of identical mass, and you were still located 700,000 kilometers from it, and stationary, you would still experience the same 27Gs as before. |
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Our equations describing Gravity at a distance allow us to PRETEND that the "source" of the gravitational attraction of the Sun is a mathematical point at the center of the Sun. Isaac Newton invented calculus (independently and almost simultaneously as Wilhelm Liebnitz) just so he could prove the math worked to let us make that simple pretense. for a black hole, though, no such pretense is necessary! BUT, with all its mass practically/actually at its central point, the hole lets us get physically closer to that central point than an equal-mass ordinary object like the Sun -- and because we can get closer, we can experience extreme gravitational effects. As mentioned in the main text, one of those effects, the "escape velocity", lets us mathematically define the event horizon as the boundary where not even light moves fast enough to escape the hole's gravity. |
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One other relevant fact concerns the gravity inside a hollow spherical shell. No matter how thick the shell, there is NO gravity anywhere inside the hollow! While you may be close to one part of the shell, and the mass of the nearby region would attract with a certain force, the much greater mass of all the rest of the farther-away parts of the shell also attract in an exactly balanced way. What this means is, if you landed on some large world of perfectly uniform composition, (ice only, for example), you might experience 1g at the surface of that world, but if you dug down to its core, at any point on the way you could stop and contemplate the "shell" of the portion of world now above you. Its gravity cancels out, so only the part of the world still between you and its center would exhibit overall gravity upon you. Thus, as you approached the center of that world, you would weigh less and less, until, at the center, the whole world becomes just a surrounding shell. |
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The preceding description is not accurate for the Earth or the Sun, because those bodies do not have uniform composition all the way through. They are enough denser at their cores that digging down would actually cause you to weigh MORE, for at least part of the journey. But that increase in weight is nothing like what you could experience near a black hole, since ALL its mass is ALWAYS between you and its center. |
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[2_fries], no, no perpetual motion here. The natural "increasing Entropy" phenomenon is for the total energy of the Universe to become ever-more spread-out. Mass and black holes are both concentrated forms of energy. So, black hole evaporation, and total conversion of mass into energy BOTH constitute things that increase Entropy. A "closed" perpetual motion system is one in which Entropy is constant (or even decreases). |
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Ah.
<perpetual motion anno deleted> |
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Where are you getting the particles that you're injecting into the black hole? Surely the production of these particles will, at the very least, still require more energy than that obtained by the evaporation of the black hole. |
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[Detly], the injected particles are to be ions (and electrons) obtained from ordinary matter. Their charges let us accelerate and aim them enough to hit a tiny black hole. And no, a small-enough black hole will be associated with quite-large hordes of escaping particles. If they consisted of only electrons and anti-electrons, for example, then every proton we inject is the mass-equivalent of 1835 of them -- and we can easily collect those escapees and encourage them to engage in mutual annihilation. THAT'S LOTS MORE energy than it takes to strip an electron off an ordinary atom and inject both pieces into the hole. |
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No, the biggest problem has to do with what percentage of escaping particles might be neutrinos. We don't (yet) have any good way to collect them and make them mutually annihilate, so all the escapees of that class are likely to represent wasted energy, as far as this Idea is concerned. The statistics of quantum mechanics implies (to me, anyway) that because neutrinos have very much less mass than electrons/positrons, they are very much more likely to escape a black hole (via Hawking radiation) than electrons/positrons. Well, perhaps neutrinos won't remain so elusive forever. |
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