Could a black hole be used as an artificial gravity generator for a spaceship?

[Deleted member 690984]

It's one of those staples of sci-fi. Unless you're going for a hard sci-fi that uses rotation or linear acceleration to achieve simulated gravity, your starship will likely use "gravity plating". As we all know, gravity plating is just a plot device, usually for shows with more limited budgets where they can't simulate artificial gravity all of the time. Unless the hypothetical graviton actually exists and we can somehow use it to manipulate gravity, there's no way we're going to create gravity plating.

This got me thinking. I was reading about hypothetical forms of propulsion, and one was the black hole drive. The concept goes that you create a small black hole at just the right size and mass whereby it will emit a steady flow of energy via radiation (rather than evaporating too quickly or too slowly) which you can then harvest to power your ship. Black holes are also dense objects with a high gravitational pull, which gave me an idea - could an artificially generated black hole be used as a gravity generator?

The black hole would likely have to go at the base of the ship, where the ship is designed like a building in space, similar to the concept of a starship using linear acceleration. The only problem is the closer you go to the black hole, the stronger its gravitational effects.

What do you think? Could this concept be viable?

 

[Ibix]

Where did the energy to create your black hole come from? The total Hawking radiation emitted won't exceed the energy used to do so, and any significant radiation temperature will mean a very short lifetime.

Close to small black holes the gravitational gradient tends to be rather extreme, so you'd probably find that the gravity near the middle of the bottom deck was crazy strong while it was much weaker at the edge of the deck and likely negligible a few decks up.

Quite a lot of hand-waving needed, I think.

 

[Deleted member 690984]

Where did the energy to create your black hole come from? The total Hawking radiation emitted won't exceed the energy used to do so, and any significant radiation temperature will mean a very short lifetime.

Close to small black holes the gravitational gradient tends to be rather extreme, so you'd probably find that the gravity near the middle of the bottom deck was crazy strong while it was much weaker at the edge of the deck and likely negligible a few decks up.

Quite a lot of hand-waving needed, I think.

The gravitational gradient is the one big problem I'm having. The energy isn't too much of a problem - it's science-fiction, there has to be some suspension of disbelief involved.

 

[Ibix]

The energy isn't too much of a problem - it's science-fiction, there has to be some suspension of disbelief involved.

The problem is that you need a small black hole for a high radiation temperature in order to power anything (and to be able to carry it round), but that means a very short lifetime. So you need to keep topping up your black hole to prevent it evaporating - at which point one wonders why you don't just use whatever is topping it up as an energy source. Not to mention that the radiation comes out in all directions, so you need your hole enclosed to collect all of it.

Basically, the hole is working as a (probably rather inefficient) battery.

The gravitational gradient is the one big problem I'm having.

And it's a worse problem with a smaller hole.

 

[stevendaryl]

Here’s my idea for artificial gravity: Powerful fans in the ceiling blowing everything towards th floor. I’m afraid it wouldn’t satisfy the equivalence principle, though.

 

[DaveC426913]

Something you'll have to figure out is how massive does the BH have to be to provide tolerable gravity at some arbitrary distance, and then derive how much energy it would take to move a ship that masses that much? I think you'll find it untenable.

 

[Ibix]

Here’s my idea for artificial gravity: Powerful fans in the ceiling blowing everything towards th floor. I’m afraid it wouldn’t satisfy the equivalence principle, though.

Cool idea though!

...I'll get my coat.

 

[stefan r]

The problem is that you need a small black hole for a high radiation temperature in order to power anything (and to be able to carry it round), but that means a very short lifetime. So you need to keep topping up your black hole to prevent it evaporating - at which point one wonders why you don't just use whatever is topping it up as an energy source. Not to mention that the radiation comes out in all directions, so you need your hole enclosed to collect all of it.

Basically, the hole is working as a (probably rather inefficient) battery.

And it's a worse problem with a smaller hole.

Converting mass into energy is most of the point. Your are "using whatever is topping it up as an energy source".

The radius of the event horizon is determined by gravity. The Hawking temperature is effected by the radius. If the kugelblitz is suspended inside of a sphere made of gravity plating then the power output can be adjusted. Uses the same type of dial the captain uses to adjust the artificial gravity on cruisers. With the artificial gravity on full power you can feed garbage into the black hole, spin it up, and increase its mass.

The gravity plates give us a way of producing the kugelblitzen. Drop an array of gravity plates onto a neutron star. That creates a cluster of black holes. Some of the microblack holes will be ejected by 3-body dynamics. This project will also eject vast quantities of neutron-rich heavy elements.

If you have anti-gravity plates you can harvest material/energy from black holes. Anti-gravity would be useful for extracting energy from a wide variety of astronomical objects. While it is in a low or no gravity field the pressure in the core would cause rapid expansion. That allows the core to transfer more heat into the surrounding envelope. Restoring (or enhancing?) gravity allows the core to collapse back to a higher density and pressure. The shock wave from the expanding core could blow off the out layers of a star (object).

 

[White Hole]

This is the exact principle that my AGG (Anti-Gravity Generators) use. They use the warp drive's gravitational pull. Granted, this would create some worrying tidal forces, but hey, it's Sci-fi. I can bend the rules whenever it's impossible not too.

 

[Melbourne Guy]

What do you think? Could this concept be viable?

It's sci-fi, so sure

Alastair Reynolds used black holes to produce the gravity for worldlets in Revenger, though not for the drives of the ship as far as I recall, and he touched on tidal effects, though it was not a main component of the story.

I've written two novels with artificial gravity. In one, it was elaborated as it drove the plot (the character who created it successfully reconciled QM and GR and AG just fell out!) but in the other it was incidental and entirely presumptive. I don't even think I touched on how it might have been done, merely that it had been. I did dwell on it for a few scenes, though, tunable AG on a spaceship can lead to some interesting combat sequences.

Which is really my answer to pretty much any question about tech in science fiction. Use it however you need for the plot. Describe it if required...don't bother describing if that works, but be consistent either way. Deus ex machina is hardly ever satisfying to readers, and ultimately, you're writing a story for them. Engaging characters and interesting plots matter more than whether a black hole drive might actually work in real life.