Minecrafter1

Paper uses a different method for calculating the lifespans. We'll never know for sure until we do experiments. It would actually be a good thing if lifespans were long, because then it would be much easier to make an SBH.

Oh. I didn't read the paper right. Totally dead wrong. This is even more AWESOME than I realized earlier. The paper says "1*10^9 tons of "nuclear lasers", and 1*10^-3 times the mass of the lasers become gamma rays. I did the math real quick, and right off the bat the newly formed SBH has a mass of 1 million tons. That means it would be only radiating 56 petawatts or so, and would last for the next 16 years or more if you didn't feed it. Now, uh, nuclear lasers....I'm not certain, but it kind of sounds like he meant 10^9 tons of atomic bombs and their lasing media. So basically it's a gigantic bomb that produces a black hole in one titantic explosion, apparently. It all goes up in an amazing flash and at the middle you find a new SBH. Not sure what the solar panels are for...

Why not convert it to 2013 dollars (or the closest you can find) That is nowhere near as impressive a number unless you convert it to dollars we are used to.

Thing about it, I'm not sure how to set up the orbital mechanics to create that collision. The concept is simple : somehow store up a gigantic amount of energy in the form of particle beams that will all intersect on your nascent event horizon at the same time. I mean, at that instant, the black hole is so small that it is at the very bottom of the chart in the linked paper, and is emitting many thousands of petawatts of energy. You need to cram enough mass into it in a fraction of a second to get the mass to the point it can be dealt with. Tricky business, but once you do it, you have an engine you can use for years.

Well, suppose you have an incredible amount of matter set up to come at your black hole. It occurs to me that you could set up a stream of collimated particles into orbit around some body . You would set up thousands of these streams, all orbiting in some complex matter, with course correction stations out in space in various places to maintain the loops. All told, you could have thousands of tons of matter out there in the form of high speed particles. There would be a convergence point where all the orbits intersected. You'd set the gamma ray lasers up there. You turn on the lasers, and for an instant, an event horizon exists. It would be such a tiny black hole that it would be radiating energy away just as fast as it was gaining it. But you time it so all these particle beams also enter the event horizon at the same instant. In theory, maybe the black hole could gain enough tons of mass that it doesn't emit energy faster than you can charge it up.

Well, ironically, the only thing of value to these aliens would be best left untouched. What is unique about the earth? Well, it's full of life, presumably life that is unique to Earth's history itself. As far as raw materials are concerned, there is so much else in our solar system to mine and collect from first. Also, we are at the bottom of a gravity well and have an atmosphere : much easier and more convenient to harvest low gravity objects in a vacuum. (especially since engines and mass drivers work so much better in vacuum) If I were aliens, I would declare our planet as a nature reserve and only swat "escapees" from our planet in the same way I would tranq elephants escaping from a zoo. I'd also occasionally collect samples from the planet or send tourists (the tourists would, like tourists to our zoos, be careful not to disturb the wildlife). Maybe their tour buses are invisible or they are nanoscale or hidden from our dumb animal senses some other way.

Agree. Rereading the paper, it noted a very nasty problem with antimatter containment. The same forces that would keep your antimatter contained in your ship (you might store it all as frozen anti-hydrogen or as pellets of anti-iron or something) will tend to force normal matter that leaks in to your containment system towards the center. In turn, if you collided with interstellar dust, it would punch into your antimatter confinement tanks and release enough energy to destroy them (and your ship, possibly) The other problem with antimatter is that even if you solve this problem, it is not an energy source. Your starship would gradually burn through it's antimatter fuel load and be out. If you get to another star system safely, before you can leave you would have to build a gigantic facility, much larger than your ship, to collect sunlight and convert the energy to antimatter. The conversion process may also be horrendously inefficient (like 0.00001%), although, I have read of reasonably efficient proposals. Versus an SBH ship, where you just have to grab a few hundred thousand tons of fresh matter from somewhere and you're ready to go. I guess if your black hole is a "picky eater", you might need straight hydrogen, but if it can eat heavier elements, then anything will work. (no one knows how big a particle a small SBH can consume) You can also refuel as you fly, apparently, there's about 1 kg of interstellar hydrogen for every "earth sized volume" of space you fly through according to wikipedia. Not quite sure how that equates to your SBH's fuel consumption, whether or not you would gain fuel or not.

Well, I'm no physicist, but that 140 petawatts is mostly gamma rays. As I understand it, at that wavelength they will tend to pass through matter - this is why you need so much mass to shield against them. Radiowaves get stopped with a thin grid of metal, infrared requires a thicker solid barrier, visible light requires a more solid material than infrared, UV requires an even stronger and heavier barrier, and so on. In "laymans" knowledge it seems obvious that gamma rays will buzz right on through most matter, including a thin acretion disk that is just a few thousand kilograms of matter yet to be eaten by the SBH. I agree there are too many uncertainties as to what will happen. No one ever knows how big a particle an SBH this size can even eat. Which reminds me : a future civilization, if it were possible, might choose to deliberately make a big enough SBH to actually quench our star. Think about how much energy our star wastes every day - more than we could ever use. If we converted it to a giant black hole, it would radiate a lot less energy and would live far longer. Also, it would be a lot more efficient since it would eventually convert 100% of it's mass to gamma rays. (versus stellar fusion which will convert everything to iron and then stop)

Re-read parts of the paper, thinking about actual mission designs. Apparently, smaller and more energetic black holes give you a lot more acceleration. So, that brings to mind a modified engine proposal : for an interstellar mission, you use 2 black holes in your engine. If the mission is going to take 100 years (ship-time), you use a small and energetic one with a short lifespan to get you up to speed. You feed it as you fly to keep the power output constant. You have a longer-lived, less energetic black hole orbiting around it in the engine chamber. Now, you deorbit the short-lived black hole so that it falls into the long lived one. I wonder if this will work... If it does, and they combine into one really long lived black hole, it works great. You have the masses figured out so that the black hole will lose mass over the next 100 years as you fly, providing the ship energy and thrust to sustain interstellar "cruising" speed. (and you gather interstellar matter as you fly using a ramscoop to reduce the amount of mass of the ship you lose) As you get near the destination, you turn the engine around, and, as it loses mass, the engine naturally "throttles up" and it slows you down into the target system. Once you arrive in system, you find an asteroid to eat and "quench" your engine, filling it full of mass to give it a much lower output, enough to power your new civilization but not waste excessive amounts of mass. This reduces energy lost pointlessly accelerating you to high relativistic velocities : any civilization capable of this kind of technology would have immortal crewmembers who could sleep or otherwise go dormant for long journeys, so there's no reason to go faster than 0.9c or 0.5c or so. Thinking about it further, I realize that just making the ship far more massive, such that you can quench the SBH with matter stored aboard the ship once you reach interstellar cruising speeds makes far more sense. (since that extra mass will also make your engine more efficient since it absorbs more of the gamma rays) You could reach anywhere in our galaxy with this technology, although, you probably would want to make a refueling stop every few hundred years at some random star. Assuming any star has at least some mass around it (hard to think of a reason one wouldn't), and since your ship can basically eat any old matter to use as fuel, you're good to go. I wonder if you could skim above a star itself to gather gas, with this kind of engine performance, maybe so. For an intergalactic journey : dunno. Only idea that comes to mind is you'd launch a ship, with incredible mass, and "multi-core" engine using many small and energetic SBHs. Get up to a high fraction of C, and combine them all into one big black hole with the 20,000+ year lifetime needed to cross that distance of space (even with relativity helping you out, it's a darn long time). Reading off the chart, it looks like it would take combining about 20 of them. If physics won't let you combine them, then you had to have been carrying a long life SBH the entire time, and you eject the short lived ones before they explode. 20,000 years later, you use the energy from your remaining SBH to build several new ones (this is a really, really massive ship and can carry all that gear) and you use those as engines to slow you down. To be frank, it only sounds slightly more difficult than doing an interstellar journey to a nearby star. Sure, your equipment has to work for a long time, but you would have many parallel systems, and every single sub-component would have integrated self-diagnostics. When something fails, robots remove the failed part, put it into an on-board factory, and manufacture a brand new part from information stored on the ship. Unlike DNA, as long as you use MD5 and data recovery information, your blueprints will never be corrupted, even over 30,000+ years. So your ship will always know how to make new parts used in itself, and as long as it has matter and at least 1 remaining factory that can make any part, it can eventually repair any damage.

Who ever said the particle beam has to be at the speed of light? It only has to resist the photon pressure coming off the black hole for an instant, and to be sucked in by the event horizon itself when it hits it. The numbers you are talking about would make the black hole pointless, because you are investing as much energy flinging stuff into it as it releases. The paper mentions that creating an acretion disk around the black hole might be needed : then you just have to send your particles to be caught by the accretion disk. Come to think of it, you would not want the particles traveling at the speed of light or anywhere remotely close to it. You'd send them at the accretion disk at a low enough velocity that they would be slowed down by photon pressure and enter orbit around the black hole. That probably takes a very low velocity for your particle beam.

It's an interesting question to ask the following : what is the absolute best you could do? Suppose you had a molecular scan of all of earth (you basically scanned every last bit of solid rock on the earth's crust and blade of grass to atomic levels of detail). You would have a precise scan of every remaining fossil in existence, and any fragments of DNA remaining, no matter how small. For every dinosaur fossil we have found, there must be thousands or millions of them yet to be discovered. The earth is a big place, and the ground goes down for many miles. Even if there's only enough fragments of DNA left to find a few base pairs every time you find a fossil, there are a large number of fossils. Also, if you could get even a fragmentary map of a particular dinosaur's genome, you could compare it to all the genomes of the existing life that was on this planet (before you tore it all to pieces to make your molecular scan, of course) Some times, you would be able to figure out via modeling genetic drift and protein functionality what a particular protein's gene would have been. Once you have done that, you have to somehow go from this still very fragmentary map full of holes and guesses to a possible mapping for a creature that would have produced the skeleton you found as a fossil when it died. It would also have to be able to survive in what you modeled the ecosystem to be like during the era. With all this, the solution space remaining, from converging all these different constraints, is not infinitely large. It might be small enough that you could make a few "example" dinosaurs from this solution space describing all the dinosaurs that might have been, and these dinosaurs would be similar enough to one another that you would feel ok with saying they were more or less accurate to what they were originally like. I'm kinda assuming the computers needed to do these calculations are massing as much as entire planets, and are super-intelligent beings of their own right. You'd build a big theme park, floating out in space in an O'Neil habitat (remember we had to destroy the earth to map it, so no point in moving back in). This would at least solve the immunity issue - your artificial habitat could be made completely sterile of all modern earth bacteria. Of course, it must be said, the dinosaurs you created would turn out to have near human intelligence (oopsie!) and would run amock, predictably, slaughtering the robotic operators of the theme park and taking over.

Regarding warships : suppose aliens showed up with a vehicle with this kind of engine. Even if the rest of their tech is not much more advanced, such a warship would be near impossible to hit with missiles. You've got the acceleration to run away at 1 G for years, literally. You also have the spare mass to pack plenty of weapons and you could just turn the engine side towards incoming fire. I guess you might be able to engage such a warship using nuclear salt water or Orion engine powered vehicles. They would have enough acceleration to keep accelerating for hours or days at 1 G or more, even if their ISP is nothing like something using a black hole.

K^2 : what's wrong with the gamma ray lasers? The only problem i can see is that the paper may not have taken into account the energy radiating off the black hole when it first forms. You just need enough lasers to add energy in faster than it is radiating off, and it will gain mass, right? The thing is, the paper assumes a manageable number of lasers, when we really might need several planet-masses worth of them in order to do that. Ok, thinking about it, it occurs to me that if you also had a bunch of particle beams timed just right, you could maybe feed the newly formed event horizon with a stream of electrons or something. That is, the very moment it forms, you have a bunch of equipment built to force more energy in to it to get the black hole above the mass level needed to keep it fed. It would look like a gigantic implosion when it happened. I mean, who knows, maybe there would be "shaped" atomic or antimatter explosions or some other method to force energy into it. It certainly sounds dramatic. Wonder if it would work. You've got a much better understanding of particle physics than me, perhaps you could generate some insights into a method that might work. Another factor is that I read that electric charge repulsion is 40 orders of magnitude stronger than gravity. Maybe there's a way you could take advantage of these forces to generate the compression needed to feed the black hole. For instance, you might feed it with an electron beam coming from one side, and a positron beam from the other, and the electrostatic forces would resist the light pressure coming off the BH as it radiates.

Maybe you create a sphere of very dense matter, and then use the lasers to compress it to black hole status? Like a sphere of iridium that you then compress down? I don't know if the idea is even "engineerable". Before I thought of this problem, what I liked about the black hole idea is that, as an engineer, it felt buildable. It doesn't require some handwaving : it's straightforward engineering. We have gamma ray lasers today (think free electron is what the authors of the paper had in mind), we just need to build a gigantic number of them. Today, such equipment is hand built by humans, but it is straightforward engineering to design and program robots to build the lasers. Today, the components that go into them are also very expensive because they are hand built, but it is entirely straightforward to design a machine ecosystem that can replicate itself. Sure, the task is a big one : it might not actually happen for 50-100+ years, but since our living bodies, even bacteria, are also "self replicating machine ecosystems", it can be done. So, some day, we have self replicating factories (using MNT they might be very small), we land one on the moon, it replicates itself, covering the lunar surface. Build some mass drivers to launch finished products into orbit, assemble those finished components into your prototype black hole engine test vehicle and black hole research facility. Assuming the actual parameters of black holes measured empirically are such that it is practical to build an engine (something I guess we'd have to discover by building our own small black hole), we're good to go. Course, bad sci fi trope would be that we discover small black holes can in fact eat fast enough to sustain themselves and grow, and some dumbass dumps one into the sun and extincts humanity.

That sounds really, really, really bad. Regarding antimatter : the advantage of this black hole method is it's a lot "safer" than antimatter. Sure the black hole is bad, but it's a bright object you can't lose track of. Though, I am wondering how the heck you could get an "escaped" black hole back to your ship, since even if you have secondary thrusters to move your ship to the black hole, the darn thing will push you away when you near it. As silly as it sounds, a "practical" black hole starship might use several separate engines, each with their own BH for redundancy. So it would not be a 1 million ton vehicle, it would be 5 or 10 million or more. The engines would be on unimaginably huge rotating joints, so you could point them at angles to give you the thrust vectors needed to collect an escaped black hole, once you repair the damaged engine. A ship this big would be able to fit the factories needed to make every single part used in itself, so it could remanufacture the broken components to build new ones. Multiple engines solves another big problem : when you arrive in orbit around a destination planet, how do you load and unload your shuttlecraft? It would be very tricky to maneuver your ship to collect shuttles since you are acclerating at 1 G all of the time. With multiple engines, you just point them in different directions to make your net thrust 0. The only problem now is approaching this ship in a shuttle on a course that won't expose you to petawatts worth of gamma rays and fry it. Not that I think you'd use biological humans at all for this kind of thing, but even electronics have trouble with too many gamma rays. Apparently they damage the crystalline lattices used in high density solid state electronics - and solid state hardware sufficiently complex to emulate a human mind would be much, much denser than any electronics humans have built so far. Antimatter, on the other hand, has to be isolated from normal matter, and to get similar performance to a black hole starship, you would need about 5% of the mass of your ship to be antimatter or more. Also, the real problem with antimatter is it is apparently trash for acceleration and specific impulse, comparatively. A huge amount of the energy is lost because the gamma rays that come out have too much energy, and, apparently, various particles that will just escape will be produced. The antimatter engine proposals on atomic rocket are basically trash for performance, comparatively. They either have good ISP and bad acceleration, or they have great acceleration and bad ISP. Look here : http://www.projectrho.com/public_html/rocket/enginelist.php . Notice how it shows a couple of high acceleration antimatter rockets, and then the "beam core", which only has an exhaust velocity of 100 million meters/second. The black hole is giving you an exhaust velocity of 300 million. The other problem is apparently antimatter is horribly energy inefficient to produce. You'd need a much larger power plant near the sun to make the antimatter, and when you run out of it, you are in trouble. With black holes, you could use the energy produced by one to build another one, far away from any star. Just need some matter to feed it once it gets going. K^2 : I see one big problem, then. When you try to create the black hole, the moment it forms it will count as a very small black hole and emit a gigantic amount of energy. How many lasers would you need to push against this gradient so the BH gains mass faster than it loses it?

Well to add insult to injury, you might as well arm the warheads when you pass a waypoint on the flight into enemy territory. So, even if you do shoot it down, the warheads might "fail deadly" and the entire plane would go up in a multi-megaton flash...that would spread the pieces of that hot reactor as fallout.

I read the following paper that describes in some detail the theory behind such an engine : http://arxiv.org/pdf/0908.1803.pdf The thing about it is, unlike some of the even more esoteric ideas like warp drives, this engine is really just an efficient way of converting matter to energy. There might be an easier way, but this is the way modern physics knows about. So the fundamental idea is definitely possible, even if this particular approach won't work. (the paper mentions difficulty determining some key characteristics about how a small black hole might behave) For those who don't read the paper, here's the TLDR : The starship engine is a black hole emitting 140 petawatts (a 30 megaton nuke going off every second) worth of gamma rays. It is being fed a steady stream of fresh matter to keep the hole the same size. The starship would weigh about 1 million tons, and the engine would just be a (very huge) parabolic gamma ray reflector, with the black hole feeding and movement hardware located where the antenna is on a satellite dish. The reason to do this is that the engine would be insanely efficient, converting mass directly into light, and would also give you a full 1 G of acceleration. You could most likely collect enough interstellar hydrogen to run your ship indefinitely. It would need about 11 grams/second of matter, or 346 tons/year. (compared to 1 million ton mass of the starship) The drawback is you cannot turn the engine off, and it is emitting all that energy in the form of gamma rays. I'm not even certain if any amount of shielding you could fit into the ship could protect biological people and leave them a big enough space to live in. The engine must burn forever : if you stop feeding the black hole, it loses mass, and eventually will release all remaining energy in one big flash when the mass is no longer enough to support an event horizon. I guess what I find so fascinating about this engine is it's the only engine design I have ever read about that would really provide a satisfactory starship. Your ship would not be a delicate collection of struts to save mass, and you'd be able to burn the engine all the time without worrying about running out of fuel. This thing could be a real warship : you'd be able to chase down anyone in any vehicle that doesn't have one, and you'd have plenty of mass for the weapons and armor. Also, the other interesting factor here is size. Whatever the minimum size is for a black hole driven ship is, anything smaller than that is trash in a world that had this technology. One final factor that fascinates me : you'd be able to see someone coming in a vehicle using this engine system a long, long, long way away. Probably on the order of light-years. No stealth at all, and since the black hole can't be turned off, it would be completely impossible to sneak up. (since even if you turn the engine exhaust the opposite direction, you have to vent all that waste heat). One final note : since the black hole is electrically charged in order to move it with the vehicle, atmosphere would be Kryptonite to this kind of engine. Once it is no longer charged, the black hole would fall out the bottom of the ship and probably end up in the core of the planet you were to land on. Assuming the black hole cannot eat faster than it loses mass, it would dissipate harmlessly...or it might destroy the planet. Either way, a big problem. Just a funny thought that a million ton starship powered by the mightiest engine imaginable, releasing 5000 times as much energy per second as all of humanity uses today, can't go anywhere near a bit of wind. The ship would be forced to carry shuttles, that, amusingly, would have a tough time getting back out of deep gravity wells using most engine technologies. You might have to beam power to the ships and use a heat exchanger or something. How to build one : You build a big sphere near the sun of gamma rays lasers focused at the same point in the middle. The power to run the lasers comes from solar panels. The sphere is not more massive than other objects humanity has already built, and it is assumed that you have self-replicating robotics which would make the job fairly straightforward. You'd need an asteroid or two to mine for the raw materials. At the center of the sphere, all the gamma rays will overlap into a tiny point about the wavelength of one gamma ray. Light has mass, and there would be enough mass in one place to generate an event horizon. You'd leave the lasers running for several years as the black hole grows in size. Hawking radiation would cause the black hole to emit gamma rays made from the mass inside the black hole. It would emit about 140 petajoules worth every second when the black hole is around the right size. Once the black hole is big enough to eat small particles, you would feed it a steady diet of electrons and protons in the form of a particle beam aimed right at it. The paper mentions this may be a problem : it is uncertain just how big a particle a black hole in this size range can actually eat. It mentions a couple of work-arounds if necessary. You would move the black hole by electrically charging it by giving it an imbalance of charge by feeding it too many electrons or protons. You would now be able to move it using electrostatics or big honking electromagnets.