A black hole in orbit: what would it be like?

[Sociotard]

Re: A black hole in orbit: what would it be like?

 

This is some awesome stuff guys. Here's a thought I had while wondering how you could contain a black hole in order to use it as a matter-to-energy device:

 

Can a black hole have an electric charge? What if we just started bombarding the thing with a load of charged particles? Well, they'd all get sucked in, but would their lines of force still leave the hole? If so, you could maybe use some big magnets to contain the thing, much as they're used to contain antimatter today. That still leaves the gravity problem, but whatever.

[Agemegos]

Re: A black hole in orbit: what would it be like?

 

Can a black hole have an electric charge?

 

Yes. Mass, charge, and angular momentum are the classical properties of a black hole. In addition to which quantum properties mean that it has entropy and temperature directly dependent on the surface area and curvature of its event horizon.

 

But when you are talking about an object with teh mass of the Moon, you will need to give it an enormous charge and use mindbogglingly srong fields to manipulate it. Remember, even though it is tiny, it still has all the inertia of an enormous moon. It still masses tens of quintillions of tonnes.

[Captain Obvious]

Re: A black hole in orbit: what would it be like?

 

I guess I skipped over the actual calculated size of this thing. Yeah, I could see a black hole that small as being too small for most of the effects I was thinking of...

 

It could still really suck as a nav hazard, though. Especially for someone exploring the planetary system for the first time. They probably wouldn't be checking too closely for anomalous gravity effects. And I would guess (with my non-physics background, once again) that it would do some nasty damage to a typical starship if they hit it, or even got a little too close.

[Agemegos]

Re: A black hole in orbit: what would it be like?

 

Yeah, if you hit it it would punch straight through your ship: it is far too massive to be deflected or diverted, and no material the ship might be made of (even GP hull) is strong enough to withstand a ship-stopping impact over an area a fraction of a millimetre across.

 

Besides which, the gradient in gravitational force is -2Gm/r^3. This obect has a mass of 7*10^22 kg, so its tidal strain at distance r is 1.86 * 10^13/r^3 Newtons per kilogram per metre. That's approximately one gravity per metre at a distance of six kilometres. One gravity per metre won't pull crew members apart, but it will be a severe strain on any sizeable spaceship.

 

Note that tidal strain falls of inversely as the cube of distance: at sixty kilometres you have only a thousandth of a gravity per metre, which shouldn't worry any ship smaller than a Death Star. But at sixty millimetres you have a tidal strain that will pull molecules apart.

 

Now, six kilometres is a tiny distance on the astronomical scale. Compare it with, for instance, the 400,000 km distance from the Earth ot the Moon. As astrogation counts things you would have to come very, very close to this thing for it to do any damage.

[keithcurtis]

Re: A black hole in orbit: what would it be like?

 

Yeah' date=' if you hit it it would punch straight through your ship: it is far too massive to be deflected or diverted, and no material the ship might be made of (even GP hull) is strong enough to withstand a ship-stopping impact over an area a fraction of a millimetre across.[/quote']

 

Ahh, but what if the GP hull was in a slaver stasis field? And you threw your warp drive into full reverse, just before tossing some piping hot tea (and cake) into your Infinite Improbability Drive? In the Negative Zone? Would your Subspace Radio even work? Answer me that, Mr. Science!!!

 

Keith ";)" Curtis

[Agemegos]

Re: A black hole in orbit: what would it be like?

 

Ahh' date=' but what if the GP hull was in a slaver stasis field? And you threw your warp drive into full reverse, just before tossing some piping hot tea (and cake) into your Infinite Improbability Drive? In the Negative Zone? Would your Subspace Radio even work? Answer me that, Mr. Science!!![/quote']

 

Well, okay, you did ask.

 

1. The GP hull in slaver stasis can safely go within an infinitesimal distance of the even horizon, but once it touches, everyone is toast.

 

2. Warp drive in full reverse is enough to get you away from anywhere except within, or in contact with the event horizon, but it won't stop the tides from pulling the ship to bits.

 

3. You can't get hot tea on the Heart of Gold: Arthur Dent tried, but the drinks machine had never heard of it. Hot tea was used to make the infinite improbability drive, not to run it. But anyway, the infinite improbability drive can get you out from inside the event horizon, but only infinitely far off in the future.

 

4. Sorry, but relativistic time dilation will throw off the tuning of your subspace radio, and you will only be able to receive provincial horse-racing stations on AM.

 

5. We are talking about an object in the orbit of Earths moon. The Negative Zone doesn't come into it. But the Twilight Zone does.

 

6. Why do you need to ask me this stuff? Don't they teach you whippersnappers anything in school these days? Show your working, and do not attempt to write on both sides of the paper at once.

[keithcurtis]

Re: A black hole in orbit: what would it be like?

 

You got you got you got REP!

 

Keith ":hail:" Curtis

[AlHazred]

Re: A black hole in orbit: what would it be like?

 

This turns out not to be the case. See http://www.physics.hmc.edu/student_projects/astro62/hawking_radiation/gammaray.html

Cool site! Rep to you!

 

See, I completely forgot about the background radiation. Just shows what happens when you assume; I should have checked my facts before opening my trap.

 

a black hole the mass of the Moon would take about 3*10^43 years to evaporate.

Actually, it's closer to 5*10^43 years, but still way shorter than the time the Universe has existed.