Wednesday 17 September 2003

Black Hole Life Preservers

From Tom Siegfried of the Dallas News :
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.

[...]

"... 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.

[...]

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.

[...]

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.

[...]

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."
All you need is a handy Faraday Cage and an electrically-charged doughnut the size of one of Saturn's rings. Don't leave home without one.

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