Wednesday, November 01, 2006

Elephant into a black hole

I guess there will be two kinds of posts in this blog - Paradoxes and Solutions. One type of post will show you two facts that are both true, yet state opposite things. The other will look at these paradox and provide apparent solutions.

To be honest, I like paradoxes more, because (ironically) they're alot easier to understand.

Here's a story that was posted recently on Digg - The elephant and the event horizon. Don't try to read the article unless you want your brain to explode or melt down. But there are some shiny pictures.

The idea here is simple - what happens when you throw an elephant into a black hole?

For one, you'll probably get a bunch of animal rights activist on your tail. And maybe some Thai warrior/protector will try to run after it to take it back. But aside from the social repercussions, what happens...physically?

I'm going to introduce a pair of characters that I'll be using a lot in this blog. One day, two friends named Steve and Anna got bored and decide to throw an elephant into a black hole. Anna will watch the elephant entering the black hole from a safe distance, and Steve the daredevil will ride the elephant into the black hole.

So what winds up happening? (Note - if at any time you get lost, just scroll down to the bolded "quick summary")

Anna watches as the black hole pulls the elephant towards it at super-fast speeds. But then something strange happens when the elephant reaches the Event Horizon (the point of no return) -- it vaporizes.
That's right...Steve and Mr. Elephant are just sailing through space when BAM, they get vaporized when they hit the event horizon. Anna detects some radiation coming out from the black hole, and thinks that the elephant smashed into a brick wall and shattered into pieces that is contained in the radiation.

That's all nice and well...but what about poor Steve? Can we travel with him during his last moments?

Steve, on the elephant, flies through space towards the black hole. Having heard about the vaporization thingy, he braces himself before he hits the event horizon. But when he finally hits it...nothing happens. Instead it's just business as usual. He and the elephant continue flying towards the black hole. Eventually the immense gravity shreds them, but overall, nothing happens at the event horizon.

Wait...what just happened?

Anna just saw the elephant get vaporized at the event horizon, its remains coming off as radiation.
Steve just went through the event horizon, and nothing special happened.

So where is the elephant, or its remains? Is it flying through space like normal, or is it no longer even tangible, existing as radiation?
From what we see, it must be at both places at once! Steve sees that it's normal, Anna sees that it's vaporized. And according to relativity, they're both right in thinking so. So the exact same elephant is in two places at once?
Wait...what if...going through the event horizon cloned the elephant? So it's not the same elephant...it's just two different elephants that have the same matter!
...but that can't be. Even the most basic laws (the first laws of thermodynamics, for example, which states that matter, energy, and information cannot be created or destroyed, only rearranged) forbid it. Quantum laws state that it isn't so, either.

So...there's the paradox, isn't it?

A quick summary - From someone looking on the outside, the elephant is vaporized when it hits the event horizon. From someone looking from the inside, the elephant goes through as normal. And science says they're both right.

What the heck is happening?

Don't try to make sense of it. Just take it all in, just as it is, piece by piece.

This, my friends, is what makes this stuff amazing, elegant, and beautiful.

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Please leave a comment if you have questions or something to say. This is mny first post, and I'd appreciate feedback :)

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