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My question was put on hold and closed:

https://physics.stackexchange.com/q/140955/

Reason given was: "We deal with mainstream physics here. Questions about the general correctness of unpublished personal theories are off topic, although specific questions evaluating new theories in the context of established science are usually allowed."

Kyle Kanos agrees with me that the elements I use in my question are mainstream physics but he thinks the combination of them is not. Sure, it won't be possible in the near or even quite distant future, but IMO it's a valid question and I've seen equally theoretical questions, even one about black hole power plants.

Please review my question and reopen it if it's on topic here. Please also read the comments of Alan Rominger and Hypnosifl.

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  • $\begingroup$ I have now removed the offending context as someone has downvoted my question. $\endgroup$ – darsie Oct 19 '14 at 18:53
  • $\begingroup$ How to feed the black hole to remain at a stable mass is a interesting question, but you lost me long before that with the electronic beings. $\endgroup$ – Olin Lathrop Oct 21 '14 at 15:10
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It's hard to take seriously any question that starts with:

I believe some life will evolve into electronic beings which can repair their bodies and potentially live as long as they have an energy source.

Having said that, I think it's an interesting question to ask whether a small black hole in some specified pressure of gas would come to an equilibrium where the outgoing Hawking radiation would balance the rate of infalling gas. The problem is that at the moment the serious physics in your question is overwhelmed by the science fiction fluff and that makes me reluctant to vote to reopen.

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  • $\begingroup$ The question is not about en.wikipedia.org/wiki/Mind_uploading#Serial_sectioning or whole brain emulation or AI. This is merely the context of my question which may also help in answering the question in this context. If it's necessary to get my question answered, I will remove this context, but I'd rather like to keep it there. $\endgroup$ – darsie Oct 19 '14 at 16:59
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    $\begingroup$ @darsie: before editing and/or reposting some research and clarification would be worth while. For example the heat from the accretion disk is likely to massively outweigh any Hawking radiation. If the black hole is spinning, and it's likely to have a very high spin, there will also be energy generated by the Penrose process. In practice I would guess Hawking radiation pressure wouldn't be an obstacle to using the black hole as a power source. $\endgroup$ – John Rennie Oct 19 '14 at 17:18
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    $\begingroup$ I did some research, that's how I calculated HR power levels of various mass BHs. I also looked up how to calculate light pressure, but I think my problem is more difficult than just assuming I'm pushing in a solar sail. OTOH, I'll calculate that. Maybe it's a useful approximation or upper limit. About the other methods, they are certainly considerable, but I can't imagine how anything can be more efficient than 100% matter>energy conversion. I'm running out of characters here. Also I think this should be in the comments of my original question. $\endgroup$ – darsie Oct 19 '14 at 17:48
  • $\begingroup$ I'm not sure what 'SF fluff' means, but I think you aren't taking mind uploading or AI serious enough. We (mankind, not me) have fully mapped the connectome (without synaptic weights) of caenorhabditis elegans and have already simulated the worm partially. I hope that vitrification of human brains/bodies will mature enough so mind uploading becomes possible in my life time so I can be on that BH. AI may advance slowly, but I have no doubt that in the near future (compared to possible life times of 10^27 years, say in much less than 1000 years) it will surpass humans. $\endgroup$ – darsie Oct 19 '14 at 18:09
  • $\begingroup$ It seems inappropriate to vote to close based on your opinion of the stated beliefs of the person asking it, if these stated beliefs have no bearing on answering the question. If someone prefaced a question with "I am a young-earth creationist and I believe in a literal global flood", and then proceeded to ask some questions about the hypothetical effect of a sudden huge influx of water on the Earth's surface that could be answered with mainstream physics, would you vote to close just because you think (as do I!) that creationism is dumb? That seems like ideological policing. $\endgroup$ – Hypnosifl Oct 19 '14 at 19:17
  • $\begingroup$ @Hypnosifl as I understand it, this is not about anyone's beliefs, this is about the post itself, and how any serious scientific question in it has been buried within too much pseudoscientific fluff. Your hypothetical example is different because the real scientific question is not obscured by a simple statement that the OP is a young earth creationist. $\endgroup$ – David Z Oct 20 '14 at 2:42
  • $\begingroup$ @David Z - what parts of the current version of the question would you call "pseudoscientific fluff"? The stuff about uploading our minds into computers has been removed (and lots of scientists take that seriously as an eventual technological possibility anyway, so I wouldn't call it 'pseudoscientific' any more than space elevators or interstellar travel). $\endgroup$ – Hypnosifl Oct 20 '14 at 2:47
  • $\begingroup$ @Hypnosifl Actually I haven't read the question. I'm explaining John's answer in different words, which I hoped would make it clear that (as I understand it) he was not objecting to the poster's beliefs, only to something in the content of the answer. $\endgroup$ – David Z Oct 20 '14 at 2:57
  • $\begingroup$ @David Z - John only referred to how the question "starts" though, not to anything else. And if you look at the original version of the question before it was edited, you can see that the starting sentence was the only one about mind uploading, there was never anything more. John never actually said the question was "buried" in pseudoscientific fluff, just "overwhelmed" by it, by which he apparently meant that the first sentence turned him off so much he couldn't take the rest seriously--just like in my hypothetical with the creationist. $\endgroup$ – Hypnosifl Oct 20 '14 at 3:18
  • $\begingroup$ @Hypnosifl it's not at all apparent that that's what he meant, and if you're claiming there's a difference between "buried" and "overwhelmed" in this context, I don't think there's any way we can have a productive discussion about this matter. $\endgroup$ – David Z Oct 20 '14 at 3:24
  • $\begingroup$ @David Z - Usually when people talk about "buried" in the context of texts they mean the part they're interested in is literally hard to find because so much of the text is made up of stuff they consider useless and irrelevant. But you were the first one to bring up the term "buried", so perhaps you didn't mean this. In any case, given that there was only a single sentence John noted his objections to, I think it's fair to infer he didn't mean "overwhelmed" in this sense of lots of text he considered pseudoscientific, but rather just that he found this single sentence overwhelming. $\endgroup$ – Hypnosifl Oct 20 '14 at 3:36
  • $\begingroup$ Also, I really would recommend reading the original version of the question, I think it's a necessary context for inferring John's likely meaning (without reading it one might speculate that he just brought up the first sentence as an example of 'pseudoscientific fluff' that was present throughout the question--I'm still not clear on whether this is the interpretation that you are advocating--but when you actually read it, this interpretation of John's comment becomes much less plausible). $\endgroup$ – Hypnosifl Oct 20 '14 at 3:43
  • $\begingroup$ @Hypnosifl (2 comments up) The interpretation in the first sentence of your comment is exactly what I meant, i.e. that the question is full of fluff of which its first sentence is just an example. Just as you consider it obvious that John did not mean "overwhelmed" in that sense, I consider it equally obvious that he did (and reading the original version of the question makes no change in my interpretation). Given this disagreement, again, I'd say it's useless to continue this exchange unless John clarifies what he meant. $\endgroup$ – David Z Oct 20 '14 at 4:53
  • $\begingroup$ @David Z - although I agree that there is no value in continuing to talk about our differing interpretation of John's meaning (hopefully he will comment himself), I think it would also be useful and relevant if you would clarify why reading the original question didn't change your mind--leaving aside the first paragraph, can you point to any specific sentences in the rest that you would consider pseudoscientific, not relevant to the question of what would be required physically to keep the size of the black hole constant? $\endgroup$ – Hypnosifl Oct 20 '14 at 5:10
  • $\begingroup$ Actually I think the question now looks fine, and in fact I've voted to reopen. $\endgroup$ – John Rennie Oct 20 '14 at 6:04
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As I said in the comments, this topic in meta seems to indicate that questions asking what mainstream theories would predict about a science-fictional scenario are on-topic (assuming the premises of the scenario don't themselves violate any physical laws, of course). And certainly mainstream physicists write papers analyzing physical solutions in general relativity that are unlikely to occur naturally and have science-fictional associations, like traversable wormholes and the Alcubierre warp bubble, discussions about these ideas are not typically closed. Likewise the theoretical possibility of an advanced civilization extracting rotational energy from a rotating black hole is sometimes discussed in textbooks, see the page here discussing two theoretical processes that have been discussed in the literature.

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