REM%IMSSS@SU-AI.ARPA (Robert Elton Maas) (03/18/86)
Although fusion isn't very efficient (compared to antimatter/matter anihilation), and antimatter/matter anihilation may be very difficult to engineer, dropping matter into a black hole is both efficient and relatively safe/simple once you have a black hole handy. Unfortunately the more matter you drop the more massive the hole gets. Fortunately the only part of the matter that ends up really in the hole is the part not converted to energy, so the more efficient you can engineer the system the slower the hole gets massive, so with close to 100% efficiency the hole lasts close to forever. What is current expert opinion on the existance of small black holes in the centers of asteroids, which you can discover by shoving the asteroid away suddenly leaving the hole in approximately its original orbit? What is current expert opinion on making black holes from scratch by some kind of microscopic implosion followed by feeding it some additional mass to bring its blackbody radiation temperature down to room temperature so it will be stable during storage before spaceship launch?
chuck@dartvax.UUCP (Chuck Simmons) (03/19/86)
> Unfortunately the more matter you drop the more massive the hole gets. > Fortunately the only part of the matter that ends up really in the > hole is the part not converted to energy, so the more efficient you > can engineer the system the slower the hole gets massive, so with > close to 100% efficiency the hole lasts close to forever. > > What is current expert opinion on the existance of small black holes > ... [quote taken out of context] The last I heard, experts were of the opinion that black holes (especially small black holes) have a tendency to evaporate. Thus most of the small black holes that may have been created in the Big Bang are no longer with us, and if we do learn how to construct small black holes, they will tend to evaporate quickly. On the other hand, if we learn how to care for and feed a black hole so that it can be used as an energy source, we won't have to worry about it growing too large. Every now and then we can simply stop feeding it and wait for it to evaporate a little. (By having lots of little black holes and only feeding one at a time, we can even keep up a continuous supply of energy.) Chuck Simmons chuck@dartvax
desj@brahms.BERKELEY.EDU (David desJardins) (03/20/86)
In article <8603181749.AA05299@s1-b.arpa> REM%IMSSS@SU-AI.ARPA (Robert Elton Maas) writes: >... dropping matter into a black hole is both efficient and >relatively safe/simple once you have a black hole handy. > >Fortunately the only part of the matter that ends up really in the >hole is the part not converted to energy, so the more efficient you >can engineer the system the slower the hole gets massive, so with >close to 100% efficiency the hole lasts close to forever. I give up. I don't have a clue what you are talking about. How is dropping things into black holes supposed to create energy (at "close to 100% efficiency")?? -- David desJardins
weemba@brahms.BERKELEY.EDU (Matthew P. Wiener) (03/20/86)
In article <12499@ucbvax.BERKELEY.EDU> desj@brahms.UUCP (David desJardins) writes: >In article <8603181749.AA05299@s1-b.arpa> REM%IMSSS@SU-AI.ARPA >(Robert Elton Maas) writes: >>... dropping matter into a black hole is both efficient and >>relatively safe/simple once you have a black hole handy. >> >>Fortunately the only part of the matter that ends up really in the >>hole is the part not converted to energy, so the more efficient you >>can engineer the system the slower the hole gets massive, so with >>close to 100% efficiency the hole lasts close to forever. > > I give up. I don't have a clue what you are talking about. How >is dropping things into black holes supposed to create energy (at >"close to 100% efficiency")?? From the gravitational potential energy difference. If I remember correctly, there are thought experiments to prove E=mc^2 based on dropping things slowly towards black holes. More reasonable is extraction from the rotational energy of a spinning black hole. An object can be sent near the black hole's equator and come back with higher kinetic energy than when it went out. There's a lot of energy available this way, as you pointed out in discussing the earth's rotational energy. The major inefficiency is extraction of usable energy from the returning projectile. There's a lovely description of this system in MTW, using garbage in, energy out! The only practical difficulty is finding a spare black hole lying around. ucbvax!brahms!weemba Matthew P Wiener/UCB Math Dept/Berkeley CA 94720