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What could be learned? There are so many things you could study by looking at a black hole. There are lots of open or partially unsolved problems that surround them: Does Hawking radiation exist? While it has been predicted theoretically, direct evidence is lacking - well, nonexistent. Stellar-mass black holes aren't the best targets - primordial black ...


55

You have bombs you can drop anywhere, there's no defense, and they're infinitely powerful. Not too different from reality. Just as in reality, you don't fight overwhelming military force with military force. You conduct asymmetric warfare. Hide. You can't hit what you can't see. Make the environmental cost too high (it eats planets). Make the collateral ...


52

You need to understand better how the event horizon works. It is a point of no return. Your implicit idea of it being a shell that destroys anything that passes is simply wrong. From physicist Matt Strassler’s blog: A horizon is not an object, but a place beyond which escape is impossible. A famous analogy is to a boat approaching a waterfall, in an ...


48

would it triggers extinction level event? Since they'd evaporate more or less instantaneously (known as Hawking radiation), releasing energy according to the famous equation beginning E=, the spaceship would last a few microseconds at best, Earth would be fine. Yes, the aliens in the ship would become extinct.


44

As mentioned, anti-gravity and or gravity generators will let you pull magic out of thin air, but let's try it without magic. I can't imagine why anyone would bother doing it, but I decided to see what happens and ended up with a totally insane project that uses a lot of carbon nanotube (CNT) and crazy amounts of energy. But, you don't need unproven ...


40

Welcome to How to destroy a black hole for dummies So, are you looking for a way to eliminate the right black hole, arent' you? Well, you're reading the right guide. But before beginning, it could be useful to make some clarifications on the nature of these galactic monsters. As Sun Tzu says, to defeat your enemy, you must first know him. Let's know what a ...


38

There is no point in sending a manned mission! As @HDE22686 noted, there are many interesting phenomena associated with black holes. Given the opportunity to study one up close, it is likely that missions will be sent. However, describing all the cool phenomena associated with black holes only means they will be studied - not that humans will be there to ...


37

Black holes are actually more like gravitational point-sources than anything. Unlike their depictions in movies, black holes emit only as much gravity as the object that they are made from. For example, if the sun were to suddenly turn into a black hole, the earth would keep orbiting it just like it normally would. That aside, the two major dangers of ...


37

This scenario is quite problematic for two main reasons: evaporation and peak wavelength. The black hole's lifetime is too short We can make a rough estimate of the properties of the Hawking radiation coming from the black hole. First, let's start with the luminosity. Since $L\propto M^{-2}$, where $L$ is luminosity and $M$ is the mass of the black hole, ...


33

A black hole with a Schwarzschild radius of 4 feet would have a mass of 137.5 x Earth and the gravity to go along with it. Such a black hole would instantly liquefy the earth as it shreds it into an accretion disk and shoots gamma rays straight through the earth's poles. There would be approximately 0 seconds for a committee to consider the problem before ...


29

Not all that much Sagittarius A* is big, but not that big. Its mass is estimated to be around 400,000 solar masses. That's a lot of gravity! But consider the Milky way is estimated to be around 1,000,000,000,000 solar masses! In all, the total gravitational effects would be minimal. The largest effect would be on stars near the center (for whom most of ...


26

Time dilation comes from gravity and/or velocity. Since the planet is not orbiting a black hole it would either have to orbit another super heavy mass or fly through space with a lorentz factor of 0.5 (when seen from earth) as that would equal time dilation of a factor 2. $t_{planet} = \gamma * t_{earth};$ with $\gamma$ being the lorentz factor of $\...


26

Start with an 0.1% of Everest-mass black hole. Stuff it into a 0.001 meter radius (1 mm) containment device. At the edge of the containment device, gravity is 0.01 m/s^2 from the black hole. This is microgravity. It emits 1.358944e+10 watts, or 3 times that of a typical nuclear reactor, and it will last 10^10 years before evaporating (slowly increasing ...


26

Black holes evaporate by emitting Hawking radiation a 1-second-life black hole has a mass of $2.28 \cdot 10^5 \ \mathrm{kg}$ A grape has far less mass than that, thus the black hole would evaporate way faster than that. An intelligent life form dropping micro black holes on Earth would thus quickly annihilate its own bombing squad in a shower of gamma ...


25

That's some extreme time dilation. It is possible, but the black hole needs to be insanely massive for your ship to orbit it without falling into the event horizon and have the proper amount of time pass. Gravitational time dilation goes like this: $$t_0 = t_f \sqrt{1-{{r_0}\over{r}}}$$ Where, $t_0$ is the proper time between events A and B for a slow-...


25

You invented it, you decide Sorry for coming off as boring but this question is of the sort: I have invented Big Magic™ for my setting. Now please tell me how this little aspect of Big Magic™ works. Well... no-one knows that except you. Especially so since you have taken a figurative hole and somehow made usable energy come out of it, energy that ...


24

Yes. You can take binary or trinary star systems and swap one of the stars for a black hole and nothing changes in the orbital dynamics. Depending on the layout of the solar system planets can orbit the stars, the black hole, or some mixture of the above. Some of those planets could be in the habitable zone (liquid water). And some of those planets could ...


23

X-ray radiation at the orbit of HDE226868 Cygnus X-1 is famous as one of the most powerful X-ray sources in the sky. According to the US Naval Observatory, the max flux of Cygnus X-1 (near the bottom of the last page on the link) is 1.2672 Crabs in the 2-10 keV range. 1.2672 Crabs is equal to $3.04\times10^{-11} \text{ W/m}^2$. I have the distance to ...


21

The answer is simple, although a bit of a cop-out: Exactly as big as if it were around a star. It's a common misconception that black holes have stronger gravity than anything else. But (ignoring general relativity) gravity is always $$F_{grav} = G\frac{m_1m_2}{r^2}$$ where $G$ is a constant, $m_1$ and $m_2$ are the masses of the objects, and $r$ is the ...


21

At that size of black hole (1% the size of the moon), the presence of the black hole in the sun wouldn't significantly change the life span of the sun. Using this calculator, we can see that the radius of such a black hole would be 10 micrometers. Not a whole lot of matter would be falling into a black hole that size compared to the rate at which the sun ...


21

Your issue is right here It seems pretty straightforward to just deposit the waste heat into the black hole Unfortunately this isn't true. The problem is that heat isn't something you can just dump into a black hole. To be clear, heat is just the random motions of atoms and molecules inside substances. There isn't a way to just "move" that into ...


21

In practice, you may not need to feed it at all - as long as you can deal with a sufficiently hefty mini black-hole. According to wiki a black hole with mass $M$ measured in kg will have: Power output $P = 3.56\times 10^{32} M^{-2}$ Watts. Evaporation time $T = 2.67\times 10^{-24} M^3$ years. So a tidy little black hole of mass $10^{11}$ kg will ...


20

Blackhole Defense by Reclaiming the offending Blackhole The OP makes it sound like arbitrarily sized black holes can be created at arbitrary locations whenever someone with sufficient authority says to do so. Presumably, these black holes can be removed when they are no longer necessary. If this removal capability exists then defense of the planet is ...


19

Good analysis by the others, but I want to add in some math here, because I'm really that nerdy. We can model the growth of a black hole by the matter it accretes. Normally, a black hole accretes matter via a (surprise, surprise) accretion disk. Analysis of this type of object is nice because it's two-dimensional, for most practical purposes. Here, though, ...


19

A black hole does not have any magic properties, it does not "radiate" time dilation or any other nonsense like that. Noticable time dilation happens when one observer moves at relativistic speeds with reference to another, or when one observer is under much higher gravitational acceleration than another. In the movie "Interstellar", the crew of a ...


19

You should watch this video about black holes. Your premise is so nonsensical for General Relativity that you might as well be asking "why is the moon made of cheese?" Um... its not. Planets cannot orbit inside the event horizon, the only direction inside the EH is towards the singularity at the center. Everything inside will not retain a form ...


19

Using your black hole from the actual size would be much smaller than a proton so it would have difficulty accreting mass because its effective cross section is very small. It may even only be able to absorb neutrinos, electrons, and gamma rays. Also, its overall gravity would still be very weak. It weighs as much as a building and you don't see people being ...


19

We cannot say what will happen because one of your assumptions is typically considered to be invalid: Physics works, except for the bit about the event horizon being gone. You can't add energy to make the event horizon go away. Paradoxically, more energy means more gravity. You can, however, add charge. The Reissner–Nordström metric defines the ...


19

From Hawking radiation? No. The Hawking radiation emitted is inversely proportional to the black hole's size. To make the black hole glow with enough light to be as bright as a star from Hawking radiation alone, it would need to be very small. The problem with very small black holes is they also have very short lifetimes due to the Hawking radiation ...


18

I recommend the Hawking radiation calculator linked by Philipp: http://xaonon.dyndns.org/hawking/ The general point is that black holes convert themselves to energy: the lifetime of a black hole is proportional to the cube of its mass, and in that time all its mass will be converted to energy per Einstein's formula $E = mc^2$ You can use this and a few ...


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