Falling into a black hole
Tags: Universe, Space, Space Exploration, Physics, Blackhole

Falling into a black hole

So what happens if you accidentally fall into one of these cosmic aberrations? Let's start by asking your space companion — we'll call her Anne — who watches in horror as you plunge toward the black hole, while she remains safely outside. From where she's floating, things are about to get weird.

As you accelerate toward the event horizon, Anne sees you stretch and contort, as if she were viewing you through a giant magnifying glass. What's more, the closer you get to the horizon the more you appear to move in slow motion.

When you reach the horizon, Anne sees you freeze, like someone has hit the pause button. You remain plastered there, motionless, stretched across the surface of the horizon as a growing heat begins to engulf you.

According to Anne, you are slowly obliterated by the stretching of space, the stopping of time and the fires of Hawking radiation. Before you ever cross over into the black hole's darkness, you're reduced to ash.

let's forget about Anne and view this gruesome scene from your point of view.

You sail straight into nature's most ominous destination without so much as a bump or a jiggle – and certainly no stretching, slowing or scalding radiation. That's because you're in freefall, and therefore you feel no gravity: something Einstein called his "happiest thought".

After all, the event horizon is not like a brick wall floating in space. It's an artefact of perspective. An observer who remains outside the black hole can't see through it, but that's not your problem. As far as you're concerned there is no horizon.

Sure, if the black hole were smaller you'd have a problem. The force of gravity would be much stronger at your feet than at your head, stretching you out like a piece of spaghetti. But lucky for you this is a big one, millions of times more massive than our Sun, so the forces that might spaghettify you are feeble enough to be ignored.

In fact, in a big enough black hole, you could live out the rest of your life pretty normally before dying at the singularity.

How normal could it really be, you might wonder, given that you're being sucked toward a rupture in the space-time continuum, pulled along against your will, unable to head back the other way?

But when you think about it, we all know that feeling, not from our experience with space but with time. Time only goes forwards, never backwards, and it pulls us along against our will, preventing us from turning around.

This isn't just an analogy. Black holes warp space and time to such an extreme that inside the black hole's horizon, space and time actually swap roles. In a sense, it really is time that pulls you in toward the singularity. You can't turn around and escape the black hole, any more than you can turn around and travel back to the past.

At this point you might want to stop and ask yourself a pressing question: What the hell is wrong with Anne? If you're chilling inside the black hole, surrounded by nothing weirder than empty space, why is she insisting that you've been burned to a crisp by radiation outside the horizon? Is she hallucinating?

Actually, Anne is being perfectly reasonable. From her point of view, you really have been burned to a crisp at the horizon. It's not an illusion. She could even collect your ashes and send them back to your loved ones.

In fact, the laws of nature require that you remain outside the black hole as seen from Anne's perspective. That's because quantum physics demands that information can never be lost. Every bit of information that accounts for your existence has to stay on the outside of the horizon, lest Anne's laws of physics be broken.

On the other hand, the laws of physics also require that you sail through the horizon without encountering hot particles or anything out of the ordinary. Otherwise you'd be in violation of Einstein's happiest thought, and his theory of general relativity.

So the laws of physics require that you be both outside the black hole in a pile of ashes and inside the black hole alive and well. Last but not least, there's a third law of physics that says information can't be cloned. You have to be in two places, but there can only be one copy of you.

Somehow, the laws of physics point us towards a conclusion that seems rather nonsensical. Physicists call this infuriating conundrum the black hole information paradox but that's a story for another time.

References-

http://www.bbc.com/earth/story/20150525-a-black-hole-would-clone-you