## Friday, October 1, 2010

### Maximizing Your Survival Time Inside the Event Horizon of a Black Hole and What to do if you have no Parachute

From Universe Today:
Here’s a scenario that will face many of us in the far future. You’re hurtling through the cosmos at nearly the speed of light in your spaceship when you take a wrong turn and pass into the event horizon of a black hole. Uh oh, you’re dead – not yet, but it’s inevitable. Since nothing, not even light can escape the pull from a black hole once it passes into the event horizon, what can you do to maximize your existence before you join the singularity as a smear of particles?

Physicists used to think that blackholes were sort of like quicksand in this situation. Once you cross the event horizon, or Schwarzschild radius, your date with the singularity is certain. It will occur at some point in the future, in a finite amount of proper time. The more you try to struggle, the faster your demise will come. It was thought that your best strategy was to do nothing at all and just freefall to your doom.

Fortunately, Geraint F. Lewis and Juliana Kwan from the School of Physics at the University of Sydney, have got some suggestions that fly in the face of this stuggle = quick death hypothesis. Their paper is called No Way Back: Maximizing survival time below the Schwarzschild event horizon, and it was recently accepted for publication in the Proceedings of the Astronomical Society of Australia.
When an unlucky victim falls into the event horizon of a black hole, they will survive for a finite amount of time. If you fall straight down into a stellar black hole, you’ll last a fraction of a second. For a supermassive black hole, you might last a few hours.

Due to the tremendous tidal forces, an unlucky victim will suffer spaghettification, where differences in gravity from your head to your feet stretch you out. But let’s not worry about that for now. You’re trying to maximize survival time.

Since you’ve got a spaceship capable of zipping around from star to star, you’ve got a powerful engine, capable of affecting your rate of descent. Point down towards the singularity and you’ll fall faster, point away and you’ll fall more slowly. Keep in mind that you’re inside a black hole, flying a spaceship capable of traveling near the speed of light, so Einstein’s theories of relativity come into play.
And it’s how you use your acceleration that defines how much personal time you’ll have left.

In a moment of panic, you may point your rocket outwards and fire it at full thrust, keeping the engine running until you arrive at the central singularity. However, Lewis and Kwan have demonstrated that in the convoluted space-time within the event horizon, such a strategy actually hastens your demise, and you’ll actually end up experiencing less time overall. So, what are you to do? Lewis and Kwan have the solution, identifying an acceleration “sweet-spot” that gives you the maximal survival time. All you have to do, once across the event horizon, is fire your rocket for a fixed amount of time, and then turn it off and enjoy the rest of the fall.

But how long should you fire your rocket for? Lewis and Kwan show this is a simple calculation involving the mass of the black hole, how powerful your rocket is, and how fast you crossed the event horizon, easily doable on a desktop computer....MORE
Previously (June 7, 2008):

Okay, the Dow Jones Industrials are Down 428 Points in the First Five Days of June. Now What?
Well, the retail guys have their lips on autopilot: "And Mr. Big, if you annualize that...", but I suppose that sounds better on the upside.

Grandmother would say something like "If the initial condition given is 'The sky is falling', your course of action would be to short sky, try the eggplant"

kottke.org guides us to:

# Free Fall

The Free Fall Research Page

 Admit it: You want to be the sole survivor of an airline disaster. You aren't looking for a disaster to happen, but if it does, you see yourself coming through it. I'm here to tell you that you're not out of touch with reality—you can do it. Sure, you'll take a few hits, and I'm not saying there won't be some sweaty flashbacks later on, but you'll make it. You'll sit up in your hospital bed and meet the press. Refreshingly, you will keep God out of your public comments, knowing that it's unfair to sing His praises when all of your dead fellow-passengers have no platform from which to offer an alternative view. Let's say your jet blows apart at 35,000 feet. You exit the aircraft, and you begin to descend independently. Now what?
 First of all, you're starting off a full mile higher than Everest, so after a few gulps of disappointing air you're going to black out. This is not a bad thing. If you have ever tried to keep your head when all about you are losing theirs, you know what I mean....MORE

Kottke's snippet:

Some survival tips for you next unplanned freefall.
...Snow is good -- soft, deep, drifted snow. Snow is lovely. Remember that you are the pilot and your body is the aircraft. By tilting forward and putting your hands at your side, you can modify your pitch and make progress not just vertically but horizontally as well. As you go down 15,000 feet, you can also go sideways two-thirds of that distance -- that's two miles! Choose your landing zone. You be the boss.
If your search discloses no trees or snow, the parachutist's "five-point landing" is useful to remember even in the absence of a parachute. Meet the ground with your feet together, and fall sideways in such a way that five parts of your body successively absorb the shock, equally and in this order: feet, calf, thigh, buttock, and shoulder. 120 divided by 5 = 24. Not bad! 24 mph is only a bit faster than the speed at which experienced parachutists land. There will be some bruising and breakage but no loss of consciousness to delay your press conference. Just be sure to apportion the 120-mph blow in equal fifths. Concentrate!