117
votes
Accepted
Is it worth sending a manned mission to a black hole?
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? ...
- 102k
53
votes
Black hole as a storage device?
I wasn’t sure how the weapon could be pulled back out, and I was thinking perhaps magnets?
Nothing can get out of the event horizon of a black hole, not even light. And light is made of ...
- 301k
48
votes
Accepted
What would happen to a modern skyscraper if it rains micro blackholes?
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 ...
- 27.5k
40
votes
How to tell a blackhole from a neutron star covered entirely by Dyson sphere painted in vantablack?
I'm surprised no one has mentioned this.
Your ultra-black Dyson sphere is easily distinguishable from a quiescent black hole or unnaturally cold neutron star by one major thing, if you're close ...
- 47.3k
39
votes
Is it worth sending a manned mission to a black hole?
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 ...
- 20.6k
39
votes
Accepted
The Moon turns into a black hole of the same mass -- what happens next?
what practical differences would arise when compared to a normal moon (such as it affecting the atmosphere)
Almost none.
There'd be no moonlight under normal circumstances, which means that no life ...
- 78.5k
37
votes
Accepted
A planet illuminated by a black hole?
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 ...
- 102k
37
votes
How do you detect and defend against micro blackhole cannon?
We'd definitely notice.
A 365000 tonne black hole has a luminosity of $2.6*10^{15}$ watts. On the K-scale of civilizations this is about 0.95.
1.0 is roughly consuming all of the energy the Sun ...
- 16k
36
votes
Accepted
How to tell a blackhole from a neutron star covered entirely by Dyson sphere painted in vantablack?
When we “see” a black hole or neutron star, we don’t see the actual body itself — they’re much too small, as well as black holes being black. So there’s no point messing around with Dyson spheres and ...
- 20.3k
36
votes
Accepted
How do you detect and defend against micro blackhole cannon?
Dont do anything.
1: a BH of that size would evaporate in 129 years (which surprised me I thought it would be shorter). This makes my point of it evaporating in microseconds moot so ignore point 1.
2: ...
- 45.7k
34
votes
Accepted
Black hole at the center of the planet
Your planet needs to be about 722500 times more massive than Earth for its core to undergo collapse into a black hole.
Leaving aside the small detail that at this point your "planet" would ...
- 9,143
32
votes
How would someone destroy a black hole that’s at the centre of a planet?
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 ...
- 4,188
30
votes
Accepted
Is it safe to orbit HDE 226868?
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 ...
- 85.8k
30
votes
Black hole as a storage device?
Could this work in any scenario?
Unfortunately not.
If you are looking for a scientifically sound explanation, even in purely theoretical terms what you're asking just is not possible. As others have ...
- 6,322
30
votes
How to tell a blackhole from a neutron star covered entirely by Dyson sphere painted in vantablack?
Vantablack doesn't reflect light, but it'll still have black body radiation based on temperature. It may be far into the infrared, but the black body curve is a signature we can recognize from a ...
- 1,935
28
votes
How to annihilate an object completely?
I mean there’s a lot of ways to do this honestly. Humans are really good at destroying things. So there are a couple ways you can completely ”destroy” something. Let’s break it down.
Physical: ...
- 5,293
28
votes
Accepted
How would a space probe determine its distance from a black hole while orbiting around it?
I am neglecting the effect of tidal forces on the integrity of any object
Well, don't be doing that! Those forces can be used to answer your question.
Given a couple of bars of known length and mass, ...
- 78.5k
27
votes
Black hole at the center of the planet
No
A natural occurring black hole that comes into existence due to mass collapsing onto itself must have more mass than the Tolman–Oppenheimer–Volkoff limit, which has been estimated to be around 2.17 ...
- 142k
26
votes
Accepted
Reasons for time dilation to happen on a habitable planet with same g force and not orbiting a black hole
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....
- 6,839
26
votes
How to build a fail-safe system for an engine that can harness energy from a Black Hole?
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 ...
- 16k
26
votes
Accepted
What happens if I shot a blackhole pellet point blank at someone?
I am NOT (not, not not) fluent in celestial mechanics, so if I'm wrong, let me know and I'll delete this answer. But...
Our favorite supervillain, Gru, has asked his most trusted scientist, Dr. ...
- 132k
25
votes
How to build a fail-safe system for an engine that can harness energy from a Black Hole?
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.
...
- 44k
25
votes
What would happen to a modern skyscraper if it rains micro blackholes?
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 ...
- 301k
24
votes
Is a solar system around a black hole possible?
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 ...
- 77.3k
22
votes
How do I feed my black hole?
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 ...
- 7,566
21
votes
Accepted
What exactly would happen if a black hole was introduced into the sun?
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 ...
- 6,766
21
votes
Black holes as heat sinks
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 ...
- 3,422
20
votes
A planet illuminated by a black hole?
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 ...
- 5,928
20
votes
Do (supermassive) black holes rotate?
Yes, supermassive black holes can spin, but your proposal for using their rotation as a timekeeping system isn't ideal.
First, the rotation period is likely quite small. The angular speed of a ...
- 102k
19
votes
Accepted
What would happen if you could remove the event horizon from Sgr A*?
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 ...
- 133k
Only top scored, non community-wiki answers of a minimum length are eligible