How is this question about a black hole passing through the solar system non-mainstream?

Question

A question of mine was closed on the grounds of being non-mainstream. Mainstream is defined below:

Mainstream physics is physics which has been accepted by a significant portion of the physics community. In the case of modern physics, if a theory has not been published in a reputable journal, it is not considered mainstream.

This definition having been written in a community answer (87 % Manishearth) to this meta question.

My question asks at what point a black hole would leave Earth uninhabitable in its approach. More specifically, I asked for an upper and lower limit, as the point it would leave Earth uninhabitable would depend on the characteristics of the black hole.

The only criticisms I got in the comments were about how a black hole wouldn't affect the solar system any differently than another object of the same mass. Now this may be true, and I posted a comment displaying willingness to edit my question to be more general if someone posted an answer showing how this is the case (though this was done after the question was closed). I get that an unnecessarily specific question is sub-par, but it is surely not grounds for closing, as it creates opportunity for more learning (they could dismantle any notion that black holes are any scarier than a passing, rogue star or something). Also, I was basing my assumptions that a black hole would decimate us differently than other massive objects on a comment made on an answer (by Fraxinus) to a question of mine on the Astronomy.SE site.

However, I may have misunderstood something, but I don't see how the criticism I received in the comments is of the type you question isn't mainstream. If this is the case, if my question was closed on different grounds than the criticisms in the comments, then I'd like to receive an explanation for this. Basically, more core question is this: How is my question not mainstream? Is it not a fact approved by the mainstream in physics, that a black hole passing through the solar system could leave earth uninhabitable? Or is this idea a crackpot hypothesis? Or is it a component of my question that is non-mainstream, like the part about x-ray radiation?

EDIT: As user rob mentioned in the comments, some users chose "Needs details or clarity" as their close-vote reason. Again though, I don't see how my question is unclear. Given how this wasn't the main reason for their close, it shouldn't be the main question here either, but if anyone wants to answer how my question was unclear as well, that'd be great.

Answer 1

I for one think the question is unclear or too broad.

“Inhabitable” is not really defined, and actually hard to define. One can imagine the surface of the Earth is cold but that doesn’t make it uninhabitable: some animals may thrive.

The physics side is also vague. You do not specify anything about the black hole or its orbital parameter, so there is probably a continuous range of solutions.

Finally, it seems to me this question is a poor fit to the site: a reasonable answer would probably take pages of computation and a non-trivial simulation on which you give no guidance whatsoever.

Asking for an estimate of the distance at which tidal forces due to a black hole of given mass would break up the Earth is a better defined problem, although I would not know how to answer this myself. At least this removes the issue of estimating timescales over which ecological factors would change enough to make the Earth inhabitable.

Answer 2

I agree in full with @ZeroTheHero. Some additional points here. There are only a few canned options to choose when voting to close, so a person closing sometimes has to choose the best fit of several that could apply. I don't remember which of the choices I selected, but there are a couple of problems with this question:

• There's no compelling evidence that I know for the idea that there are rogue black holes flying through the universe that are likely to pass through a solar system. (Not mainstream - there are some realistic arguments for BHs moving around, but the dynamics of that depends on the size and what formed them while none that I know suggest any sort of serious probability of hitting a distant solar system.)
• If one did, then the comments that you referenced apply where, gravitationally, this wouldn't be different than any other massive object passing nearby unless you got especially close. (Just a fallacy of the original question.)
• The other effects (X-rays, Hawking radiation, etc.) that you mentioned may or may not occur for a given black hole but the amount, directionality, etc. would depend a lot on the history and size of the specific black hole that happened to come through your solar system. (Not enough detail to answer, but probably also a case where if you give it enough detail you run further afoul of the first bullet.)
• Even if we make assumptions for you on all of those, then you still want someone answering to get into how those factors would or would not combine to make Earth uninhabitable. (Not physics)

For what it's worth, I also think you misunderstood the answer on Astronomy.SE that you say prompted your question here, but taking that on too is too big of a scope for me now and in this forum. Even assuming that you did understand it, note that the answer that you've identified did exactly what we've mentioned here in order to formulate an answer at all: It locked in on a specific type of black hole, made assumptions about its accretion disk, ...