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Hello!
I'm redesigning my never-to-be-finish sci-fi novel, yet another futile to come up with scientifically based interstellar travel propulsion. My latest consideration is based on article[1] and possible extensions of those ideas. Anyway, I'm looking for an independent opinions on the subject (preferably this extension, but basic theme is a fair game) and, if possible, any insight in any law that would, practically or in principle, make this concept absolutely infeasible. I hope for some flexibility on the account of moderators, not to shut this post down as misplaced original research, because, even if it may contain some original components, in it's essence, it is elaboration on existing ideas lying beyond SM.
Article [1] offers an optimal and imaginative introduction to the speculative subject of usage of black holes (BH) for energy production and spaceship propulsion and I would like to supplement their proposition with this Comment. In short, authors of [1] provide us with an assessment of possibility to manufacture a small mass black hole (~million tons, few order-of-magnitude up or down:) and it's usage in energy production and propulsion of interstellar ship. Propulsion would be established by heating collected interstellar gas via Hawking emission of black hole right to the point where thermal fusion would go underway.
Proposition considered in this Comment assumes an additional assumption of [1] that it is possible not only to feed mass to BH therefore keeping it's temperature stable, but also to feed it with charged particles to maintain a non-zero total charge of a BH. For the reasons that will become clear soon, I suggest that the total negative charge of BH is maintained by feeding it with electrons. If this is done at a certain mass range of BH, it may relax it's electric charge predominately via Hawking emission of charged muons and pions. Boltzmann factor suppresses the creation of particles with mass larger than temperature of BH, so there is a range of temperature of 100MeV - 1GeV to find a sweetspot for this. That rationale of this procedure is to have a tanker mass black hole that abundantly produces negatively charged muons via decay of emitted negative pions or through direct muon emission. The produced muon current then may be used to induce muonic fusion of hydrogen.
Muon induced fusion is a theoretically[2] and experimentally[3] well established process. This process includes formation of a muonic molecule, where proton and deuteron are binded via muon. Muon, being ~200 times more heavy than electron, forces nuclei to be much closer thus enabling nuclear reaction where He3 nucleus if formed, along with 5,5 ~MeV photon. After this reaction, muon is released, repeating this process with another proton and deuteron pair. Although muon have short time of half-life, one muon can induce up to 150 fusion reaction before it finally decays into electron, neutrino and photon.
Known drawbacks of this process today are a bottleneck of so-called alpha poisoning and the fact that the production of muons is a fairly expensive procedure. Alpha poisoning refers to a possibility for muon to remain binded to nuclear product of He3, removing it from further nuclear reactions. Production of muon is possible only on particle accelerators and are quite energetically inefficient.
Possession of a BH may solve both of these problems effectively. If proposition of the Comment and [1] turn out to be viable, it may be possible to build a spaceship propulsion system that uses BH muonic emission to burn hydrogen collected along the way via Bussard-type collectors. Unlike Bussard ramjets, it may be able to produce thrust at any speed removing know objections of Bussard's ramjet that it produces more drag than thrust at relevant speeds. Obviously, there is serious limitation to this design is scarce amount of deuterium in interstellar gas (~2.3 10^(-5) D/H ratio[4])) and that P-\mu-P fusion process is weak process, probably too slow for the purpose. Even if fusion rate would be insufficient to deliver any notable thrust on object of mass comparable to that one of BH, it feels that muon captured by proton or free muons within plasma would still deliver significant part of it's rest energy to heat up plasma. I looked at Michel parameters and expecting energy of electron from muon decay is 1/2 of maximum energy and those don't go far in thick plasma. But this is only a feeling, no detailed numbers were done.
So, if there is anyone who has done work on Hawking emission of black holes, could you comment on possible process in this setup? Are there any blunt factual or reasoning errors in this post? If I can effectively "trade" an electron for a muon, does that mean that is impossible to maintain constant charge AND mass of BH? Would it be possible to feed the BH with additional proton beam to maintain mass AND charge (so that proton current be ~11x times smaller than electron beam, like 11e+1p -> 10\mu)? Is it possible to "exhaust" most of BH Hawking power to muon emission (which may be preferred to be emitted) or at least significantly reduce intensity of accompanying Hawking photon radiation?
I reiterate what is clearly stated in [1], that is - to have this issue clear, we will have to wait for precises calculation within frame of Quantum Gravity or serious calculations in semi-classical approximation to determine orders-of-magnitude on the story. Also, I understand that potential naivety of this idea, stemming from the fact that I'm waaay off my area of expertize here, may render any serious response impossible, but still - while we wait for the TOE, I don't think it's harmful for us, sci-fi junkies, to speculate on the interstellar travel. Anyone care to join?
[1] Crane, Westmoreland "ARE BLACK HOLE STARSHIPS POSSIBLE?" arxiv 0908.1803
[2] J.D. Jackson (1957). "Catalysis of Nuclear Reactions between hydrogen isotopes by μ−-Mesons". Physical Review 106 (2): 330
[3] Alvarez L.W. et al. (1957). "Catalysis of Nuclear Reactions by μ Mesons". Physical Review 105: 1127
[4] Rogers et al. The Astrophysical Journal, 630
I'm redesigning my never-to-be-finish sci-fi novel, yet another futile to come up with scientifically based interstellar travel propulsion. My latest consideration is based on article[1] and possible extensions of those ideas. Anyway, I'm looking for an independent opinions on the subject (preferably this extension, but basic theme is a fair game) and, if possible, any insight in any law that would, practically or in principle, make this concept absolutely infeasible. I hope for some flexibility on the account of moderators, not to shut this post down as misplaced original research, because, even if it may contain some original components, in it's essence, it is elaboration on existing ideas lying beyond SM.
Article [1] offers an optimal and imaginative introduction to the speculative subject of usage of black holes (BH) for energy production and spaceship propulsion and I would like to supplement their proposition with this Comment. In short, authors of [1] provide us with an assessment of possibility to manufacture a small mass black hole (~million tons, few order-of-magnitude up or down:) and it's usage in energy production and propulsion of interstellar ship. Propulsion would be established by heating collected interstellar gas via Hawking emission of black hole right to the point where thermal fusion would go underway.
Proposition considered in this Comment assumes an additional assumption of [1] that it is possible not only to feed mass to BH therefore keeping it's temperature stable, but also to feed it with charged particles to maintain a non-zero total charge of a BH. For the reasons that will become clear soon, I suggest that the total negative charge of BH is maintained by feeding it with electrons. If this is done at a certain mass range of BH, it may relax it's electric charge predominately via Hawking emission of charged muons and pions. Boltzmann factor suppresses the creation of particles with mass larger than temperature of BH, so there is a range of temperature of 100MeV - 1GeV to find a sweetspot for this. That rationale of this procedure is to have a tanker mass black hole that abundantly produces negatively charged muons via decay of emitted negative pions or through direct muon emission. The produced muon current then may be used to induce muonic fusion of hydrogen.
Muon induced fusion is a theoretically[2] and experimentally[3] well established process. This process includes formation of a muonic molecule, where proton and deuteron are binded via muon. Muon, being ~200 times more heavy than electron, forces nuclei to be much closer thus enabling nuclear reaction where He3 nucleus if formed, along with 5,5 ~MeV photon. After this reaction, muon is released, repeating this process with another proton and deuteron pair. Although muon have short time of half-life, one muon can induce up to 150 fusion reaction before it finally decays into electron, neutrino and photon.
Known drawbacks of this process today are a bottleneck of so-called alpha poisoning and the fact that the production of muons is a fairly expensive procedure. Alpha poisoning refers to a possibility for muon to remain binded to nuclear product of He3, removing it from further nuclear reactions. Production of muon is possible only on particle accelerators and are quite energetically inefficient.
Possession of a BH may solve both of these problems effectively. If proposition of the Comment and [1] turn out to be viable, it may be possible to build a spaceship propulsion system that uses BH muonic emission to burn hydrogen collected along the way via Bussard-type collectors. Unlike Bussard ramjets, it may be able to produce thrust at any speed removing know objections of Bussard's ramjet that it produces more drag than thrust at relevant speeds. Obviously, there is serious limitation to this design is scarce amount of deuterium in interstellar gas (~2.3 10^(-5) D/H ratio[4])) and that P-\mu-P fusion process is weak process, probably too slow for the purpose. Even if fusion rate would be insufficient to deliver any notable thrust on object of mass comparable to that one of BH, it feels that muon captured by proton or free muons within plasma would still deliver significant part of it's rest energy to heat up plasma. I looked at Michel parameters and expecting energy of electron from muon decay is 1/2 of maximum energy and those don't go far in thick plasma. But this is only a feeling, no detailed numbers were done.
So, if there is anyone who has done work on Hawking emission of black holes, could you comment on possible process in this setup? Are there any blunt factual or reasoning errors in this post? If I can effectively "trade" an electron for a muon, does that mean that is impossible to maintain constant charge AND mass of BH? Would it be possible to feed the BH with additional proton beam to maintain mass AND charge (so that proton current be ~11x times smaller than electron beam, like 11e+1p -> 10\mu)? Is it possible to "exhaust" most of BH Hawking power to muon emission (which may be preferred to be emitted) or at least significantly reduce intensity of accompanying Hawking photon radiation?
I reiterate what is clearly stated in [1], that is - to have this issue clear, we will have to wait for precises calculation within frame of Quantum Gravity or serious calculations in semi-classical approximation to determine orders-of-magnitude on the story. Also, I understand that potential naivety of this idea, stemming from the fact that I'm waaay off my area of expertize here, may render any serious response impossible, but still - while we wait for the TOE, I don't think it's harmful for us, sci-fi junkies, to speculate on the interstellar travel. Anyone care to join?
[1] Crane, Westmoreland "ARE BLACK HOLE STARSHIPS POSSIBLE?" arxiv 0908.1803
[2] J.D. Jackson (1957). "Catalysis of Nuclear Reactions between hydrogen isotopes by μ−-Mesons". Physical Review 106 (2): 330
[3] Alvarez L.W. et al. (1957). "Catalysis of Nuclear Reactions by μ Mesons". Physical Review 105: 1127
[4] Rogers et al. The Astrophysical Journal, 630