Spaceship approaches black hole--what happens?

ehkzu · Feb 15, 2005

1. Say the ship is as shielded as we can manage today, but it goes over the singularity's polar X-ray jet. Everyone & everything gets fried? 2. Suppose the ship used dynamic radiation protection along the lines NASA speculatively discussed decades ago, such that the ship was wreathed in its own Van Allen belt. Would the X-ray jet still probably punch through that? My ideal plotting would have the ship's field generator increase power enough to protect the ship at least partially in the short time it spent in transit over the black hole's pole but burn out in doing so. I'll only use that if that's plausible though. 3. Then the ship would be captured by the BH's gravity well & start spiraling in. Then the tidal forces--gravity differential--would start affecting people, equipment, the ship's frame. I understand that ultimately this would shred everything. What I don't understand is what effect it would have at first. The ship would be in free fall, so why would people feel anything? Mightn't they just move faster? Also, I unerstand that the bigger the black hole the more gradual the onset of these effects. Right?

geetpurwar · Feb 16, 2005

GOOD IDEA

Saiph · Feb 16, 2005

Tidal forces: You'd still be in free fall. You'd just feel stretched as well (as eburacum45 says). X-rays would basically fry you, if they were there (not all BH's, indeed it's likely that most don't have them, as nothings going in to power it). If you get really close to the BH you would spiral in, but you've gotta be really close. It's a consequence of general relativity and gravity waves. Also, if you were going to go into a hyperbolic orbit, as eburacum45 says, while you should swing out and go into space, if you cross the event horizon on the way in....you're stuck. So don't cut it too close. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

vogon13 · Feb 16, 2005

That ssscrrrzzzzzzzzzing sound you hear is your a** turning into x-rays. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

nexium · Feb 16, 2005

Low mass black holes are much more dangerous just outside the event horizon. The billion solar mass black hole, may not give any clue of their presence until you are inside the event horizon, which means you won't ever return, but you may survive long term (in my opinion). Even half way between the singularity and the event horizon the tide effect may still be minor, and radiation levels and micro meteorites may be rare. 1 I think present technology even with probable near term improvements will not save you from the most intense polar jet, but moderate jets are likely, even negligible jets. My guess is a billion solar mass black hole can not produce a leathal jet. 3 The stuff in the accreation disk captured recently will be traveling fast in radom directions, so distructive collision is likely. Collisions produce Xrays, even very penetrating gamma rays. Your space craft could reach 0.999 c before life support failed if their is very little to collide with or it it is mostly going the same direction at the same speed. Please embellish, refute and/or comment. Neil

jschaef5 · Feb 16, 2005

Imagine going through the Event Horizon and not being able to see your feet for a breif period in time. That would be crazzzzzyyyyyy. <div class="Discussion_UserSignature"> </div>

ehkzu · Feb 17, 2005

Weeelll. First off, it would be a black hole without an accretion disk, hence, it seems, not much of a polar jet. My spaceship is a ball about half a mile in diameter with spin gravity and both active and passive radiation protection--passive from storing ship's water in layer just under hull surface. Active from generated Van Allen belt (using the NASA research I cited previously). I'm trying to cook up an accident that would ideally strain but not break the ship and make the active radiation barrier quit working--metaphorically speaking, blowing a fuse, frying something. I need no accretion disk to make the ship blunder upon the black hole by it being undetectable at a distance. Moreover, I plan to champion a school of scifi I call the "one black box per story" school--that is, to limit myself to only one truly improbable item. And my faster than light drive is just that, so I have to be faithful to what we know with everything else. And I count having characters do something they wouldn't really do as a black box, just as surely as an antigravity machine or a Star Trek transporter is. Ditto tossing in contrived events. So for this moment in my story it currently looks like I can have my black box (star drive) pop my ship into normal space near previously uncharted no-accretion-disk black hole with glancing blow from relatively weak polar jet sufficient to knock out or seriously degrade Van Allen belt, meanwhile the black hole whips the ship around the hole in a hot hyperbolic orbit that gives ship's occupants scary wrenching experience near event horizon but doensn't kill them. Ship hurtles away from the hole needing various repairs and lacking normal radiation shielding, forcing ship's complement to congregate in center of ship, using whole radial mass of ship for shielding but having to do without normal spin gravity of course. So is that plausible? Basically I want to stress my characters and produce the revel

henryhallam · Feb 17, 2005

That sounds pretty good. Just one comment: the artificial Van Allen belt won't protect from xrays and gamma radiation at all, because photons aren't affected by electric or magnetic fields (they have no charge). If I were you I'd have the van allen belt generator be destroyed by tides or by an overload while -trying- to protect against the intense xray burst (although it would have to be a pretty stupid machine to do that). Sounds like a good story!

nikshliker · Feb 17, 2005

would a large mass BH and a small mass (ie. singularity.. or maybe not :/) BH have the same density?

nexium · Feb 17, 2005

The density of massive black holes is low. Medium mass black holes are very dence and low mass black holes, if any, have extreme density/ perhaps trillions of times the density of water. We know little about the singularity as it is at the center of the event horizon, from which no information can escape. If your ship has enough power, and enough fuel, it may be able to escape after it enteres the event horizon, but mainstream opinion is escape is impossible. My guess is the fast items in the accretion disk are even faster and more dangerous inside the accretion disk. Neil

nexium · Feb 17, 2005

The artificial Van Allen belt will likely be powered by a very large super-conductior loop. Since it is very large, it is valnerable to even slight gravity gradient. It is also valnerable to a very strong magnetic field which is likely near a black hole. A damaged loop can be operated at reduced current = reduced protection. The entire loop could be vaporized, but a small portion is more likely. The loop repair will require one to several persons to EVA = extra vehicular activity. It may take weeks to get the loop up to maximum safe current after the repairs. A very large loop needs many gigawatt hours to reach full current after which losses are very close to zero. Xrays are photons which are little affected by strong magnetic fields, so dense shields are needed. I think the jet also has ions which the artificial Van Allen belt can deflect. The accretion disk definitely has ions and colisions which produce photons. Neil

ehkzu · Feb 17, 2005

I certainly agree with the "avoid! avoid!" thought. I'm positing my ship popping into normal space (again, I'm only using one true black box, and that's the star drive) near an uncharted black hole--which, once charted, will be studiously avoided. Interstellar equivalent of a drunk driver suddenly careening toward you across the median strip. So the close encounter with the black hole is purely unintentional on the ship's part. An accident.

ehkzu · Feb 17, 2005

Nothing we know can escape an event horizon, to be sure. That's my black box. But like I said, I promise that's the only one! Hence my peppering this forum with questions, so I can make sure that's the only one. And since it is my only black box it's a doozy. Can cross universe membranes (as string theory posits).

ehkzu · Feb 17, 2005

Tumbling, huh? I'd like to hear more about that. The ship's about 1/2 mile in diameter & spins just fast enough to produce ~1G at the equator under the water supply/radiation shield. So it zips around Mr. BH and starts tumbling? Seems like once it's going away from the hole the law of inertia would make it continue...only maybe something like violent gyroscopic precession? That would throw folks around, wouldn't it? They'd be seatbelted for the jump, but such protection wold only go so far of course. I'd never thought of tumbling. So cool.

Saiph · Feb 21, 2005

all good, except, why'd you put yourself at 3 trillion kilometers (a good fraction of a light year away, that's what, .2 ly?)? You're radius was 3 billion km........... Gotcha, 3 billion km is 3 trillion m. And you even have it bold! that silly error out of the way: Looks good to me, though I don't have a calculator on hand at the moment and I'm notoriously lazy. But it makes sense, since tidal forces are due to the difference in gravity between two points. Shifting the distance by 1 m in 10^12 isn't going to do much at all. Also, such a notion is born up under the weight of other references, as I believe Kip Thorne's book mentions the same thing. you'd get torn to bits after entering the black hole. I could do a little legwork and compare the analytical expressions for gravity and tidal forces to see if they show the expected trend (which I think they do, cause IIRC tidal forces drop off with an r^3 power). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Feb 21, 2005

nexium - What is a medium mass black hole? The smallest supermassive black hole is described in this link: http://www.space.com/scienceastronomy/050221_little_blackhole.html It is at the center of galaxy NGC 4395 and is about 300,000 solar masses. Would you consider that a medium mass black hole? There is an enormous gap between that mass and the mass of low-mass black holes which are typically just a few solar masses in mass. Supermassive black holes are incredibly more massive. For example, the estimated mass of the black hole at the center of the Milky Way has recently been upped from 2.6 million solar masses to between 3.2 million and 4 million solar masses. See this link: http://www.space.com/scienceastronomy/mystery_monday_031124.html

newtonian · Feb 21, 2005

Shilappadikaram - So, at that radius from a billion solar mass black hole, 3,000,000,000 km, what would be escape velocity? Can you post figures for a 3 or 4 million solar mass black holes such as lies at the center of the Milky Way? Thank you for your informative posts, btw.

ehkzu · Feb 22, 2005

Ship is spherical, partly to provide spin gravity, partly to facilitate Van Allen belt, partly because such a design is more resitant to just this sort of situation. Humans tend to visualize something like a water-based ship--bow, stern etc. when you say "space ship." Even the term we use invites thinking of it that way. My space ship has a pinnace that is rather shiplike, but that's because it's designed to work in atmospheres. The space ship itself stays in space always. Ship thrown into a big wobble sounds good to me. I've spent a lot of time on boats moving two ways at once (typically, oscillating at anchor in wavy water) & it has quite an effect on passengers! Without killing them, though. Though some have wished for surcease no doubt.

Saiph · Feb 22, 2005

escape velocity is always the speed of light at the event horizon. It is defined to be such. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

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