New type of black holes – Non interacting low-mass black hole
science.sciencemag.org
science.sciencemag.org
I really hope we never learn of the existence of black holes in the kiloton range. If you think intelligences can annihilate themselves with nukes... how about sucking your planet away from the inside out?
Toss something over that either hoovers up your planet, or bakes it if a near miss. Tricky to store, though.
Working backwards, 1 megaton per second (4x10^9 megawatts) gives us a black hole of 3x10^8 kg.
In actual fact, moving mount Everest To The Moon is trivial in comparison with the task of creating a black hole. It's a feat only accessible to Kardashev type 2, at the very least 1.5, civilisations. We are talking about civilisations that can move small planets at will.
The most credible approach is to build giant gamma-ray lasers, and focus so much energy into a spot to small, that the weight of light itself will collapse the spot into a tiny black hole made of pure energy, Kugelblitz.
Once you would have a black hole formed that way, you could continue force-feeding it with lasers or particle beams to weigh whatever amount you desire. It would be a very energy-inefficient process.
At some point the black hole reaches a mass where it's Eddington limit allows it to feed by 'normal' means faster than it evaporates by hawking radiation. At that point it could server to convert matter to energy.
... Ignoring the HUGE gap between smashing together a few atoms so a small fraction of their bits evaporate and smashing them so hard they pretty much disappear.
I asked "so if I want to use a black hole to replace a 60 watt light bulb, how much mass do I need?" And the answer is, roughly that of Phobos. It would also last over 10^22 years, so it might even be cost effective!
If such a thing existed, there would likely be more than 1. How long would it take such an object to consume a star like our sun if it grazed or hit the star, vs a harmless hyperbolic flyby?
Using this calculator, we find that a black hole with the mass of 433 Eros, 6.687E15 kg, would be quite hot, some 18 million kelvin, but emitting just 8 watts of power, and be 0.009 nanometres in radius. Pretty hard to find.
Let's try something smaller. 162173 Ryugu, the rock that Hayabusa2 landed on, is only 4.5E11 kg. This gives you a much brighter hole: 1758 megawatts at 2.72657E11 kelvin.
Interestingly, this may make it harder to detect! Its blackbody emission peak is at 9,211 KeV, and the Chandra X-Ray observatory only goes up to 10 KeV. (Focusing very-high-energy photons is not easy) You'd have to detect it from the fraction of total power it emits lower down in the spectrum.
Answer: About 350 earth masses.
Question: After thinking about it, living on a black hole is clearly impractical, but what if I want to replace my heating system with one? What size black hole will produce a comfortable temperature of 70 F?
Answer: Roughly the mass of Ceres.
Question: I want to go see what an event horizon looks like up close, so what size black hole is needed for the gravity to be 1G at its "surface" for optimal sightseeing?
Answer: About a trillion solar masses. It might be a little tricky finding or making one that large, as the largest known in galaxy centers are on the order of 10^10, not 10^12.
This doesn't make any sense to me. By definition at the event horizon gravity is enough to keep light from escaping. Light can easily escape from 1G.
But the event horizon of such a black hole would be far larger than that of the Earth. Move 6400 km away, and you'll still have a gravity of ~1G.
Rinse and repeat, and you'll find that even light won't be able to escape.
That's a hell of a lot of energy. (If I'm doing the math right, the potential energy difference is on the order of ~20% of the rest mass at the event horizon)
Without thinking too deeply, I suspect the issue is that you could never be stopped at that location in the first place, unlike Earth's surface.
Answer: The appropriate mass is roughly the size of a WWII destroyer, or somewhat more than the largest dump truck in the world. There might be a drawback in that the energy release will be about 50,000 megatons per second. That might affect how fast your egg cooks.
Since 50,000 megatons/sec is the starting value, and it'll get bigger as those three minutes count down.
People dismiss that as astronomically unlikely, but it must have happened many times somewhere in the universe. The average person doesn't win the lottery once in their life, but someone does.
I believe we're beginning to appreciate that just like there are more small objects in the solar system than large ones, and there are more small stars than large ones, there are significantly more solitary planets than stars or even brown dwarfs, and they would be almost as hard to see coming as a black hole until they got close.
There are many disasters that at least microbes could recover from, but anything the size of Mars that wandered in would, I presume liquefy and sterilize the entire planet. It would be so unexotic and yet humans would be completely impotent to do anything.
It's hypothesised that a Mars-sized planet once collided with Earth in the early history of the solar system (about 4.5 billion years ago), creating our moon today:
Do you have any links with more info on this?
Charles Stross' book Incandescence is about (amongst other things) a race of sentient insects that hide inside a small asteroid orbiting a quasar that had had an encounter with a black hole sometime in the distant past, and had been ripped apart... but was now orbiting close enough to the star to be mostly safe. Maybe.
Ergo, the number of planet-destroying black holes running around is likely to be small.
The much bigger risk is having Earth's orbit disrupted slightly by a passing solar-mass scale black hole. We wouldn't get much warning that such a thing was coming, but it could alter our orbit enough to get us into thermal trouble.
This article is about a binary system, which I would argue meets your criteria.
If the black hole were manufactured, and/or being used as a weapon, there's no reason it should hit the sun, and every reason it would hit a planet.
Now I think some of the other responses illustrated why this is not a problem if our current model of black holes is valid. The "what if" in one of those books I mentioned is "what if there was more exotic physics that allowed small black holes to be stable?"
https://www.goodreads.com/book/show/513160.The_Ring_of_Charo...
Doesn’t this fit the general criteria of a Dyson Sphere or Swarm?
Not to be all tin foil hat, just neat to think about.
Physics. Entropy.
If it absorbed energy that touched it, it would heat up. You could then use the difference between it and its cooler surroundings to run an engine. Waste heat from the engine could then be absorbed to keep the engine running. You'd have created a perpetual motion machine, which is considered impossible.
In a closed system of a star, the sphere, and the outer space eventually energy will flow from the star to the outer space region.
There's no perfect insulation. (See also Maxwell's demon.)
Of course detection is a different matter altogether. Hiding better and better is possible. But if you really want to hide a Dyson swarm is not the best way :)
It is theoretically possible to direct it to some extent (at the cost of raising entropy elsewhere) but it would require massive effort for no good reason.
Once you do direct it, someone will still see you if they are in the path of the beam. It appears to be an exercise in futility.
No, but you could direct enough of it that anything left is too dim to see unless you've got really good eyes ("eyes" in this case being whatever sensors we're using to detect black-body radiation).
> someone will still see you if they are in the path of the beam.
Space is big. What's the chance that we'd actually cross paths with that beam?
On the other hand, space is big. That beam would probably hit something eventually, and I suspect in that case we might pick up a reflection.
> It appears to be an exercise in futility.
Assuming the point is actually to hide. Maybe instead it's an attempt to recapture some of that energy otherwise lost as heat?
[s-b] https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
I find the name interesting since, mini black holes are one hypothesis concerning Dark Matter, and also Weakly Interacting Massive Particles. Google also doesn't seem like Non-interacting black holes are common nomenclature. How do these names get created?
> Constraints on the giant’s mass and radius imply that the unseen companion is 3.3+2.8−0.7 solar masses, indicating that it is a noninteracting low-mass black hole or an unexpectedly massive neutron star.
Presumably, further observations will help determine what it is.
But we know it is non interacting because it Doppler shifts a nearby object in the binary systems these scientists are observing.
Being a binary system, unless the objects are at beyond perfect equilibrium with respect to their accelerations, the objects will eventually collide (in a true binary system). In other words, the Doppler shifting object must be actually falling, however slowly, into the black hole.
My question is this: Can we assume that the object is heating up and emiting additional x rays