The Physics of Building a Black Hole Powered Starship [pdf]

http://arxiv.org/pdf/0908.1803v1

by awwx • 17 years ago

44 25 17 years ago

arxiv.org

caffeine• 17 years ago

This is really, really cool. And this is obviously how they powered Rama.

bioweek2• 17 years ago

They don't seem to mention how to contain the black hole. What holds its position steady within the spaceship?

If we made a large enough one say 1/2 earth mass, we'd get free "artificial" gravity on the spaceship.

amix• 17 years ago

Their proposed blackholes are small - some of their calculations use 4 × 10^11 grams [440.924 tons ~ comparable to Empire State Building which weights about 300.000 tons].

randallsquared• 17 years ago

The radiation involved means that you probably couldn't shield a human well enough to be close enough to one of these black holes to feel gravity. Not to mention tidal forces.

bioweek2• 17 years ago

I meant, how do you stop the black hole from hitting the spaceship, moving around, falling out the back, etc?

awwx• 17 years ago

They touch on this briefly at the top of page 11: "The most optimistic approach is to solve requirements 2 [accelerate the black hole to keep it with the ship] and 3 [feeding the black hole with matter so that it doesn't evaporate] together by attaching particle beams to the body of the ship behind the BH and beaming in matter. This would both accelerate the SBH, since BHs “move when you push them” (see [3] p270), and add mass to the SBH, extending the lifetime."

The engineering details are left as an exercise for the reader :-)

nicara2• 17 years ago

"It is now known that any prolonged human presence deeper in space would need to be behind a shield of the effective strength of two feet of lead, which would weigh 400 tonnes for a small capsule."

Uhm, the first thing that comes to my mind - regardless of whether this black hole propulsion might actually work - is the amount of lead we have available. Just building the spaceship seems to be just as much a problem as accelerating it..

thaumaturgy• 17 years ago

Effective shielding against cosmic radiation is possibly an even greater problem in interplanetary travel than propulsion.

The solution will probably come from materials science, but at the moment I don't think there's enough effort being concentrated on this problem to solve it in my lifetime.

electromagnetic2• 17 years ago

Would placing the spaceships crew behind its black hole engine provide adequate shielding from cosmic radiation and blue-shifted photons/particles? Killing two birds with one black hole, so to speak.

Also, wouldn't being in such proximity to a black hole negate the need for time dilation effects of speed anyway? If you can build black holes, speed is meaningless as you essentially have a stasis machine. You could travel at .1c, reach Alpha Centauri in 40+ years and never even age a day if you can get close enough to the event horizon.

hegemonicon2• 17 years ago

The world is a big place - annual lead production is approximately 7 million metric tons.

Source: http://www.financialexpress.com/news/lead-uses-that-go-back-...

nicara2• 17 years ago

Sure, and I admit I have no idea how much lead building such a spaceship might take, but keep in mind 2 things:

1) "More than half of the lead currently used comes from recycling." (from your article) - Once the spaceship is built and has left Earth, the lead is essentially gone (for the time being), so the more of those we build, the fewer lead we will have to recycle, and it will get even more difficult to build additional ones.

2) 400 tons for a small capsule, and consider they're proposing a spaceship in which multiple people could live in autonomously, i.e. they need places to live in, but also room to grow food, process their waste, etc. So I'd guess it's much higher than you seem to have assumed.

Oh and btw, I'm fairly certain we also need much of that lead on earth - hence why we're producing so much of it in the first place, so it's not like we have some spare lead in the order of magnitude of, say, 10000s (I'm really just guessing here, though) of tons lying around collecting dust.

warfangle• 17 years ago

One thing the author doesn't address is why use lead at all? We know that Earth's magnetic field is what protects us here on the ground. If we could manufacture black holes, doesn't it seem possible that we could manufacture a magnetic field powerful enough to surround said ship and protect it?

fizx• 17 years ago

Earth is big, so all of that flux is pretty spread out. I wouldn't want to be close to a small portable magnet able to generate that size of magnetic field.

But hey, we're talking about highly hypothetical situations, so I'm sure we could make it work.

smhinsey2• 17 years ago

You don't actually need to use lead. The key phrase there is "effective strength" so if you have a massive supply of energy at your fingertips, it may be feasible to divert some of it towards the creation of an artificial magnetosphere similar to Earth's own.

Of course you could also use water (obviously in much greater volume), which is a good thing to have in large quantities anyway while you're in space, and is evidently not all that uncommon, at least throughout our solar system.

icodestuff• 17 years ago

How much water do you need? Are we talking a pond or the Caspian Sea in space?

bitwize• 17 years ago

I saw this headline and flashed back to the Gunbuster Science Lessons.

"Dimensional Wave Super String Excitation Degenerated Radius Jump Gravitational Field Super-light Speed Navigation. WARP for short."

The Physics of Building a Black Hole Powered Starship [pdf]

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