Re: A black hole life preserver

LOL - Never new science could be so much fun!!!

On Mon, 2003-09-15 at 17:33, Kevin Balentine wrote:
> The link for this story is:
>
http://www.dallasnews.com/health/columnists/tsiegfried/stories/091503dnl
ivtomco
> l.33516.html
> 
> I think you have to register to view these stories so I thought I
would just 
> post it for everyone to read (I work at The Dallas Morning News so I'm
not 
> going to feel guilty for posting the whole thing :-)
> 
> I have to give Tom kudos for the Highlander reference.
> 
> Doughnut can delay death for black hole tourist 
> 
> By TOM SIEGFRIED / The Dallas Morning News 
> 
> When you toss an endangered swimmer a life preserver, you should
really call it 
> a death delayer. 
> 
> After all, nobody lives forever, except the Highlander, and even he'd
be in 
> trouble if he fell into a black hole. 
> 
> Today's question is, when the Highlander dives into a black hole, is
there any 
> point in providing him with a death-delaying life preserver? And the
answer, 
> actually, is yes, say J. Richard Gott III and Deborah Freedman. 
> 
> Dr. Gott, of Princeton University, and Ms. Freedman, of Harvard, have 
> calculated a way to prolong your life, or at least reduce your agony,
as a 
> black hole's gravity sucks you in and rips you to shreds. You just
need to 
> surround yourself with a gigantic electrically charged doughnut. 
> 
> If you fall into a black hole unprotected, gravity draws all parts of
your body 
> toward the center of the black hole. So your left side will be pulled
to the 
> right and your right side to the left. If you go in feet first, the 
> gravitational pull will be much stronger on your shoes than your head,
tending 
> to make you instantly thinner and taller. 
> 
> "It is like being stretched on a rack and simultaneously crushed in an
iron 
> maiden," the two researchers write in a new paper submitted to the
journal 
> Physical Review D. 
> 
> Such gravitational (or "tidal acceleration") forces don't hurt, up to
a point. 
> Fighter pilots can withstand forces up to 9 G's or so  nine times the
normal 
> pull of gravity. 
> 
> "But beyond 10 G's, the tidal acceleration will cause pain and
dismemberment," 
> the scientists write in their paper, available on the World Wide Web
at 
> xxx.lanl.gov/abs/astro-ph/0308325. 
> 
> So at some point, your journey to the black hole's center will turn
into 
> painful torture. 
> 
> (Actually, the torture can begin even before you reach the black
hole's outer 
> boundary, the event horizon. For large black holes  greater than
13,800 times 
> the mass of the sun  crossing the event horizon remains within the
acceptable 
> range of G-forces. But small black holes have masses of only a few
suns. For 
> those, you'll start stretching before you cross the border.) 
> 
> Anyway, the good news is that the time of torture passes pretty
quickly. In 
> fact, from the start of the pain to getting crunched out of existence 
> altogether comes to less than a 10th of a second, the scientists
calculate. 
> 
> But a life preserver	er, death delayer  can prolong your pain-free
travel 
> time and make the torture time even shorter. 
> 
> It has to be big  about the size of one of Saturn's rings and the mass
of a 
> large asteroid. But when diving into a black hole with this huge ring 
> surrounding you, the pull of the ring on you will cancel the pull of
the black 
> hole. 
> 
> As you fall closer to the black hole's center, its pull on you
increases. But 
> the black hole tugs on the ring, too, compressing it so that more of
its mass 
> is closer to you. So the ring's pull on you increases, counteracting
the black 
> hole's efforts to crush you. 
> 
> "Your head is being pulled downward by that ring, and your feet are
being 
> pulled upward, so it just counters the tidal force that the black hole
is 
> giving," Dr. Gott said in a telephone interview. 
> 
> To keep the ring from collapsing under its own weight, it must be
electrically 
> charged (electrical repulsion counters the ring's self-gravity).
Unfortunately, 
> the electrical fields would fry you, so you need to encase yourself in
a 
> protective container known as a Faraday cage. But that's pretty simple
compared 
> to making the giant doughnut to begin with. 
> 
> If all works well till then, the ring can keep you comfortable up to
6,760 G's. 
> After that you'd be tortured for a mere three one-thousandths of a
second. 
> 
> "You really wouldn't know what hit you," Dr. Gott and Ms. Freedman
write. 
> 
> If that still bothers you, you can reduce the torture time even more.
Instead 
> of falling in feet first, assume the fetal position. Then align the
line 
> connecting your shoulders so it points toward the black hole's center.
With a 
> ring suitably adjusted for your new size, you can reduce the torture
time to 
> less than two one-thousandths of a second. 
> 
> Of course, another approach to avoiding such torture is simply staying
away 
> from black holes. But that's not very much fun. And having fun with
black holes 
> is what such exercises are all about. 
> 
> "This business that you're ripped apart when going into a black hole
is 
> something that's said in every astronomy book," Dr. Gott said. "We
just 
> wondered if there was something you could actually do about it." 
> 
> The calculations in the Gott-Freedman paper can be grasped by a bright
high 
> school student; these death-delaying scenarios offer insights into the
basics 
> of Einstein's general relativity and fundamental principles of
physics. 
> Analyzing such seemingly silly situations can give students  and
scientists  
> a more tangible grasp of what nature is really like in realms outside 
> earthbound experience. 
> 
> Besides, there really could be practical applications someday, when 
> interstellar travelers want to explore black holes or perhaps neutron
stars. 
> Maybe some sort of doughnutlike death delayer would help keep you
alive when 
> encountering such objects. 
> 
> "An adjustable-radius, actively oriented life preserver might enable
you to 
> venture closer than would otherwise have been the case," the
scientists write, 
> "and still return safely home from the adventure." 
> 
-- 
With kind regards
Claus Paludan