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Mokele

Sci-fi black hole questions

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Ok, so without too much background, my sister and I were discussing our various writing projects and how much "sci" should be in "sci-fi", and we got onto a question I have about a particular villain I'm writing.

 

Basically, the villain has the power to warp spacetime into a small massless singularity (warping space without having any mass in there to do it - 'how' is never explained or known), in effect creating a black hole, and has the rather unfortunate tendency of doing this on inhabited worlds, leading to predictable results. I want to check several things about this scenario:

 

1) Assuming someone *is* able to do this, and the 'pseudo-black-hole' begins sucking in mass, will it eventually reach a point where sufficient mass has been sucked in to make the hole self-sustaining (the mass generates the singularity and not the villain's space-bending powers)?

 

2) If one of these 'pseudo-black-holes' is stopped before consuming enough mass, what happens? Will the already-compacted mass explode now that nothing is compressing it? Or will it just sit there like a super-dense lump?

 

3) What would this even look like? Would there be enough material in sea-level air to produce a noticable ecretion disk? Would it be an ecretion disk or sphere, and would the 'black hole' be visible as a black sphere?

 

4) Not specifically black-hole related, but assuming the villain did something like "warp" spacetime in a highly concentrated area (such as within some poor bastard's chest), this would kill them, right? Probably in an exceptionally gruesome manner?

 

Mokele

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first of all, im not an expert, but ill give it a go.

 

1) Assuming someone *is* able to do this, and the 'pseudo-black-hole' begins sucking in mass, will it eventually reach a point where sufficient mass has been sucked in to make the hole self-sustaining (the mass generates the singularity and not the villain's space-bending powers)?

 

ya, i think so. once theres a singularity at all i think that it would collapse and be a black hole. just of small size at first.

 

2) If one of these 'pseudo-black-holes' is stopped before consuming enough mass, what happens? Will the already-compacted mass explode now that nothing is compressing it? Or will it just sit there like a super-dense lump?

 

hmm. i think what happens in a black hole is that something doesnt get sucked into a singularity within another, i think it gets transfered to energy. like an abomb. just alot more atoms.

 

What would this even look like? Would there be enough material in sea-level air to produce a noticable ecretion disk? Would it be an ecretion disk or sphere, and would the 'black hole' be visible as a black sphere?

 

you cant see a black hole. as for an ecration disk, i think it depends on what worlds your chucking in there and how much mass they have.

 

) Not specifically black-hole related, but assuming the villain did something like "warp" spacetime in a highly concentrated area (such as within some poor bastard's chest), this would kill them, right? Probably in an exceptionally gruesome manner?

 

ya, i think thatd just about do it.

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Thanks. Anyone else with more expertise in the subject?

 

Anyone? Bueller? Bueller?

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If the singularity is massless, would it not be an extreme "pinch point" in spacetime but without the gravity well associated with a black hole? I don't see how it would suck anything in - things would have to intersect with it due to their own movement into that region of space, surely? And they would not be gravitationally prevented from leaving again. Right? :confused:

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I have no idea, hence why I'm asking. I was under the impression that the distortion in space-time actually is what causes things to move into gravity wells and, in effect, causes gravity. Is that not the case?

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Now that it comes up, I am actually not sure. I thought that the sheer gravitational mass of a black hole was what caused that mass to collapse in on itself, and that in turn caused the spacial distortion. I am thinking of it like a vacuum cleaner - the tubes and bag are the spacial distortions, and the pressure differential is gravity. Turn the vac off (i.e. magically suspend gravity) and stuff nearby and in the tubes is no longer attracted to the dust bag. That could be profound ignorance of the mechanics of black holes on my part though.

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My sister didn't bat an eye at it, but she's in optics, and freely admits she's forgotten a lot of her astrophysics.

 

I did find something saying curved spacetime causes gravity, but it's in the introduction of the Wikipedia article on gravity, so in about 10 minutes it'll say that peanuts cause gravity.

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10 minutes after that there will be a picture of Tom Cruise causing gravity.

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I've only scanned this (sorry! will read it more carefully when I've some more time)

 

But, if it's just a singularity it would be indistinguishable from a blackhole, and any amount of mass would turn it into a true blackhole, as for self sustaining, you'd need to calculate the evaporation time compared to the rate at which stuff is being sucked in which is situation dependent...

 

Also most of what I've written requires singualrities to exist and they don't so we'd really need a quantum theory of gravity to answer this in any great detail...

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So, anyone else?

 

What would happen in a black hole's gravitational field were "turned off"? Would the accumulated mass explode?

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"Turned off" completely, or just turned off the villain's artificial gravity? If the latter, then if it's already a black hole I don't see why it would behave differently than any other black hole, i.e. it would either evaporate or grow, depending on its size and the rate at which matter is being added. If the former, isn't that pretty much impossible to say? I thought the idea of a singularity is that the conventional rules of "what would happen" break down?

 

As for your question #4, though, I think "not necessarily." It would really depend on the mass of the singularity, I'm thinking. A black hole with the mass of only a few tons, say, is still only going to have the gravity of a few tons, which is to say very little. It's radius of destruction (a field strong enough to rip stuff to shreds) would surely be microscopic, maybe even on the atomic scale. You'd have to do the math yourself, but I'm guessing unless it's really massive (or an "artificial distortion" equivalent to a really massive black hole), it's just going to fall right through a person, leaving just a tiny, tiny hole behind.

 

Actually, it would fall straight through to the center of the Earth, and keep going most of the way up the other side. And back and forth again, through the Earth, leaving tiny but widening (and widening at an increasing rate) tunnels behind as it absorbs everything in its path, until eventually it's massive enough to cut a decent swath, at which point I'm thinking we start getting more and more earthquakes. And eventually, of course, it will swallow the whole planet. But we'd all be dead by that time anyway...

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or it gets trapped in the center of the inner core and regardless of its radius of destruction wouldnt matter much. Due to earths pressure inward, matter will be forced inside black hole and over long long long x10 time it grows, more it grow the faster the rate of matter swallowed increases :D so soo nwe have black hole instead of earth :D

 

Or if ur lucky enough you get a black hole with 0 momentum, very low mass would let it just float and its going to evaporate :D

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Ok, so without too much background, my sister and I were discussing our various writing projects and how much "sci" should be in "sci-fi", and we got onto a question I have about a particular villain I'm writing.

 

Basically, the villain has the power to warp spacetime into a small massless singularity (warping space without having any mass in there to do it - 'how' is never explained or known), in effect creating a black hole, and has the rather unfortunate tendency of doing this on inhabited worlds, leading to predictable results. I want to check several things about this scenario:

 

Mokele

 

Well.. This would be a so-called naked singularity and would be violating the cosmic censorship (which has been reopened for debate), but yet, doubt this could happen. A singularity in GR space-time typically is a function of mass so I can't really see this being a feasible thought experiment.

 

1) Assuming someone *is* able to do this, and the 'pseudo-black-hole' begins sucking in mass, will it eventually reach a point where sufficient mass has been sucked in to make the hole self-sustaining (the mass generates the singularity and not the villain's space-bending powers)?

 

Ok, so now we assume the associated mass is there (like a mini created black hole from the LHC let's say).

 

In reality , any small black hole of these scales would most likely be so unstable , they would break down.. but more interestingly, most likely they would be so minute, they would interact less with atoms than even neutrinos (earth herself would be a 4 mm black hole .. [ok, an artificial black hole is the only time I will accept a S.R. hold, so ok maybe 8 mm then]). Any larger black hole which in fact interacted with mass, would probably be sustained yes, and would create such an enormous gravitational force, earth would just be ZWIP, sucked in.

 

2) If one of these 'pseudo-black-holes' is stopped before consuming enough mass, what happens? Will the already-compacted mass explode now that nothing is compressing it? Or will it just sit there like a super-dense lump?

 

 

BHs as we know them, are stable bar Hawking radiation. There are no compressing factors in an already established BH. It generates it's own existence, so additional mass only makes it 'grow'. Stopping mass would not make it explode.

 

3) What would this even look like? Would there be enough material in sea-level air to produce a noticable ecretion disk? Would it be an ecretion disk or sphere, and would the 'black hole' be visible as a black sphere?

 

Again, any BH of any size which is large enough to start interacting with baryons and leptons anywhere in the area of earth would most likely destroy Earth exponentially.. The time it would take to suck us in, would be according to initial size and placement. Earth would probably become an accretion disk but we are talking this happening on anything from t = 0 (interaction with baryons/leptons) till lol no, this would be pure guesswork from my side as we have no statistical data to play with in such a scenario (but it would nonetheless be exponential). {snowball effect}.

 

 

4) Not specifically black-hole related, but assuming the villain did something like "warp" spacetime in a highly concentrated area (such as within some poor bastard's chest), this would kill them, right? Probably in an exceptionally gruesome manner?

 

Mokele

 

Again, if that BH woulds first be large enough to interact with baryons/leptons, when it would first be large enough to start affecting the molecules, it would not take long before any larger constructs would all get sucked in. (If that guy would get sucked in, so would Earth pretty quickly thereafter).

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Ok, so without too much background, my sister and I were discussing our various writing projects and how much "sci" should be in "sci-fi", and we got onto a question I have about a particular villain I'm writing.

 

"Sci" is what separates scifi from straight fantasy. Individual preferences vary. I like lots of sci in my fi.

 

Basically, the villain has the power to warp spacetime into a small massless singularity (warping space without having any mass in there to do it - 'how' is never explained or known), in effect creating a black hole, and has the rather unfortunate tendency of doing this on inhabited worlds, leading to predictable results. I want to check several things about this scenario:

 

1) Assuming someone *is* able to do this, and the 'pseudo-black-hole' begins sucking in mass, will it eventually reach a point where sufficient mass has been sucked in to make the hole self-sustaining (the mass generates the singularity and not the villain's space-bending powers)?

 

Yes. Black holes evaporate by pair production (Hawking radiation), the rate increasing asymptotically as the mass decreases. Above a certain mass (planetary?), the rate is slow enough that you don't notice the evaporation. I'm sure you can find the equation for this, probably in Wikipedia, and play with the mass/time parameters to your heart's content.

 

2) If one of these 'pseudo-black-holes' is stopped before consuming enough mass, what happens? Will the already-compacted mass explode now that nothing is compressing it? Or will it just sit there like a super-dense lump?

 

Small black holes evaporate quickly; the evaporation looks like hard radiation, increasing exponentially in intensity. Big bang at the end...

 

3) What would this even look like? Would there be enough material in sea-level air to produce a noticable ecretion disk? Would it be an ecretion disk or sphere, and would the 'black hole' be visible as a black sphere?

 

I don't think you get an accretion disk unless the thing is spinning. You would probably see a very bright, hot sphere, as air heated to plasma temperatures while compressing and falling in. That sphere, of course, would be immediately plunging into the ground, and probably sending a geyser of superheated plasma out the bore hole. You'd only see a black sphere if you managed to float it in a vacuum.

 

4) Not specifically black-hole related, but assuming the villain did something like "warp" spacetime in a highly concentrated area (such as within some poor bastard's chest), this would kill them, right? Probably in an exceptionally gruesome manner?

 

Mokele

 

Yep, most likely. A pinch hard enough to simulate a small black hole would suck mass into the warp, and when released would essentially explode.

 

Enjoy!

 

Grant

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Thanks, very helpful! Now, time to write some death, destruction, and the horrendously inappropriate suggestion of stashing a mini-black-hole under the sink so nobody has to take the garbage out anymore.

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Thanks, very helpful! Now, time to write some death, destruction, and the horrendously inappropriate suggestion of stashing a mini-black-hole under the sink so nobody has to take the garbage out anymore.

 

I have this vision of a box emblazoned with the warning: DO NOT OPEN - NO USER SERVICABLE PARTS INSIDE.

 

Black holes would be ... hard to handle. Obviously, you can't just pick one up, even with tongs :rolleyes: Most proposed BH wranglers would use electrical charge as a handle: pump the BH full of electrons, and keep the charged BH in a strong electrical field. I'll leave it to you to calculate how strong the field has to be in order to support the weight of a small BH, not to mention keeping it centered in its enclosure. Wouldn't do to have the BH bumping up against the walls... :eek: Well, not so much walls as radiation shielding.

 

You'd probably want to have the box anchored very solidly to the foundation, and even then you'd have to worry about earthquakes. Between the gravitational gradient and the ultra-powerful electromagnetic fields, I'm not sure you could keep silverware in your kitchen. You could put the box in a Faraday cage for the EM fields, but every time you opened the top to drop in your garbage, it would snatch the watch off your wrist.

 

Frankly, I wouldn't go anywhere near the house...

 

Now I'm imagining a funny scene in which the apoplectic OSHA inspector goes ballistic :D

 

Enjoy,

 

Grant

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I have this vision of a box emblazoned with the warning: DO NOT OPEN - NO USER SERVICABLE PARTS INSIDE.

 

Opening case will void warranty and minor planetary systems.

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Opening case will void warranty and minor planetary systems.

 

LOL, that line is classic!

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Honestly, it would be pretty standard, given the irresponsibility and outright stupidity of pretty much all of the characters. The 12th spoken line is "I wonder what this button does?" and it gets worse from there.

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