Comments on: Squeezing a few nanoseconds of life out of a black hole trip http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/ I am an astronomer, writer, and skeptic. I likes reality the way it is, and I aims to keep it that way. My real name is Phil Plait, and I run the Bad Astronomy blog. Mon, 09 Nov 2009 12:14:14 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: nate http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-152930 nate Sat, 31 Jan 2009 01:54:42 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-152930 no one is ever going to know unless we go to one. this is all speculation and theory. no equation will give us the answer or prove anything. what we think we know is all a guess from what little man knows about the universe. mankind will never truly know what happens when he ventures to close to a black hole because it will never happen. i really dont think we would see the back of our own heads if we were that lucky. i dont buy that theory or many others no one is ever going to know unless we go to one. this is all speculation and theory. no equation will give us the answer or prove anything. what we think we know is all a guess from what little man knows about the universe. mankind will never truly know what happens when he ventures to close to a black hole because it will never happen. i really dont think we would see the back of our own heads if we were that lucky. i dont buy that theory or many others

]]> By: icemith http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-36122 icemith Mon, 21 May 2007 19:18:19 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-36122 The problem relating to "spagettification", (mentioned in BA's link), where the closer part of your body is actually accellerated faster, because it is marginally closer to the singularity, can be partially solved by laying "flat", ie. - as if floating as sky-divers do. Similarly, the spacecraft would present its flattest surface (probably upside-down so the center-of -interest, the Black Hole itself, could be seen thru the Observation windows), and this would cause less stretch for those happy little nano-seconds of extra time again. Every little bit helps. (Anyone for bungy-jumping?) Ivan. The problem relating to “spagettification”, (mentioned in BA’s link), where the closer part of your body is actually accellerated faster, because it is marginally closer to the singularity, can be partially solved by laying “flat”, ie. – as if floating as sky-divers do.

Similarly, the spacecraft would present its flattest surface (probably upside-down so the center-of -interest, the Black Hole itself, could be seen thru the Observation windows), and this would cause less stretch for those happy little nano-seconds of extra time again.

Every little bit helps. (Anyone for bungy-jumping?)

Ivan.

]]> By: Irishman http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-36121 Irishman Mon, 14 May 2007 20:07:42 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-36121 A typical rocket works more like your tether than an escape velocity condition. That is because the rocket produces thrust over time, while the "escape velocity" assumes the velocity is instantaneously applied and then no more thrust is added. If you assume constant thrust over time greater than the downward pull, then the escape velocity is irrelevant. However, the black hole situation is a bit different. Acceleration requires thrust, which is an expenditure of energy. Dangling on a tether over the event horizon would require a substantial amount of energy to thrust you back over the horizon. I believe the requirement is on the order of infinity. It would also require an exceptionally strong tether. I suspect as soon as you crossed the event horizon your tether would sever due to internal stresses (assuming it lasted that long). If somehow the tether were infinitely strong (and stronger than the tension), then your space ship would have a very difficult time maintaining stationkeeping while being pulled in by your infinite mass. Or maybe there'd be a rift in the space-time continuum and you'd pop back safely into "real space" some billion light years away in another quadrant and have to proceed back home. ;-) A typical rocket works more like your tether than an escape velocity condition. That is because the rocket produces thrust over time, while the “escape velocity” assumes the velocity is instantaneously applied and then no more thrust is added. If you assume constant thrust over time greater than the downward pull, then the escape velocity is irrelevant.

However, the black hole situation is a bit different. Acceleration requires thrust, which is an expenditure of energy. Dangling on a tether over the event horizon would require a substantial amount of energy to thrust you back over the horizon. I believe the requirement is on the order of infinity. It would also require an exceptionally strong tether. I suspect as soon as you crossed the event horizon your tether would sever due to internal stresses (assuming it lasted that long). If somehow the tether were infinitely strong (and stronger than the tension), then your space ship would have a very difficult time maintaining stationkeeping while being pulled in by your infinite mass.

Or maybe there’d be a rift in the space-time continuum and you’d pop back safely into “real space” some billion light years away in another quadrant and have to proceed back home. ;-)

]]> By: james http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-36120 james Mon, 14 May 2007 07:01:59 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-36120 Can I heartily recomend Gregory Benford's 'Galactic Center Saga'? High jinks in an overpopulated galaxy where the human empire has colapsed, the dominant AI species regard us as an annoyance, and the supermassive black hole in the centre of the galaxy has entered a 'feeding' phase. It has been years but I think that 'Furious Gulf' is the one where they enter the event horizon (the black hole being so big that the tidal effects are acceptable) Can I heartily recomend Gregory Benford’s ‘Galactic Center Saga’?

High jinks in an overpopulated galaxy where the human empire has colapsed, the dominant AI species regard us as an annoyance, and the supermassive black hole in the centre of the galaxy has entered a ‘feeding’ phase.

It has been years but I think that ‘Furious Gulf’ is the one where they enter the event horizon (the black hole being so big that the tidal effects are acceptable)

]]> By: Gary Ansorge http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-36104 Gary Ansorge Sun, 13 May 2007 02:28:48 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-36104 If you take an elevator to geo-sync orbit, it's true your velocity need never approach 11 km/sec however,,,heh,here it comes,,,your potential energy and kinetic energy will be identical at 24,000 km and a rotational velocity of about 1500 km/hr as it would have been if you had been given an instantenous velocity at earths surface of 11 km/sec. It's really not about velocity, though that's what's usually used when describing how rockets/space drives/etc get us off the planet. It's just easier to talk about the instaneous velocity rather than K.E.= 1/2 MV^2 and Potential energy of Mass x Acceleration x Height. It's really all about the total energy of the craft. That ties into the energy required to escape a black hole, where the potential energy at the event horizen approachs infinity, so the kinetic enery to escape must be greater than that, and unless you're into transfinite numbers, that ain't possible,,,in this space /time, anyway,,,unless you're a tachyon,,, Gary 7 If you take an elevator to geo-sync orbit, it’s true your velocity need never approach 11 km/sec however,,,heh,here it comes,,,your potential energy and kinetic energy will be identical at 24,000 km and a rotational velocity of about 1500 km/hr as it would have been if you had been given an instantenous velocity at earths surface of 11 km/sec. It’s really not about velocity, though that’s what’s usually used when describing how rockets/space drives/etc get us off the planet. It’s just easier to talk about the instaneous velocity rather than K.E.= 1/2 MV^2 and Potential energy of Mass x Acceleration x Height.

It’s really all about the total energy of the craft. That ties into the energy required to escape a black hole, where the potential energy at the event horizen approachs infinity, so the kinetic enery to escape must be greater than that, and unless you’re into transfinite numbers, that ain’t possible,,,in this space /time, anyway,,,unless you’re a tachyon,,,

Gary 7

]]> By: The Web Pen Blog » Blog Archive » Roundup - Week Of May 5 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-36119 The Web Pen Blog » Blog Archive » Roundup - Week Of May 5 Sat, 12 May 2007 15:24:51 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-36119 [...] have an expert here today who is going to give up tips on surviving a freefall into a black hole… for a few nanoseconds longer anyway. He will also teach you a new word: [...] [...] have an expert here today who is going to give up tips on surviving a freefall into a black hole… for a few nanoseconds longer anyway. He will also teach you a new word: [...]

]]> By: Max Fagin http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/comment-page-1/#comment-36118 Max Fagin Sat, 12 May 2007 14:59:09 +0000 http://blogs.discovermagazine.com/badastronomy/2007/05/11/squeezing-a-few-nanoseconds-of-life-out-of-a-black-hole-trip/#comment-36118 "anyway, what i wanted to say: you don’t fire a rocket to 11km/s in one big blast (not if anything goes according to plan) but in a rather more slow and ‘gentle’ way… but you would reach this speed to escape earth!" Not if you start from a higher altitude. I see now where the idea went wrong, but I'm still confident that escape velocity gets smaller with altitude. Getting away from Earth if you're already at the distance of the moon doesn't require accelerating past 11 km/sec. “anyway, what i wanted to say: you don’t fire a rocket to 11km/s in one big blast (not if anything goes according to plan) but in a rather more slow and ‘gentle’ way… but you would reach this speed to escape earth!”

Not if you start from a higher altitude. I see now where the idea went wrong, but I’m still confident that escape velocity gets smaller with altitude. Getting away from Earth if you’re already at the distance of the moon doesn’t require accelerating past 11 km/sec.

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