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(Live Science)   Elusive dark energy is still real to scientists, guy in bleachers   (livescience.com) divider line 1
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1445 clicks; posted to Geek » on 12 Sep 2012 at 6:46 PM (2 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2012-09-13 09:37:14 AM  
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LoneWolf343: Considering that time also started at the beginning of the univers


I'm a programmer, and as a result, I like to think of spacetime as an addressing system. From a given event in the universe, every other event that ever occurred or will occur can be given an address relative to that event. The address takes 4 components- three to establish its location in space, one to establish its location in time.

Each address is unique- no two events can share the same 4-d address in spacetime. There are also unaddressable events, like for example, the inside of a black hole. There are no spacetime coordinates that we can use out here to address an event in there. The event horizon creates a barrier that limits our ability to meaningfully discuss what occurs inside of a black hole. There is some information that leaks out, certainly, but we still can't address a space-time coordinate inside the black hole. At the event horizon, time inside the black hole stops relative to an observer outside the black hole. It takes an infinite number of seconds outside for one second to pass inside. Now, that's absurd, since we know black holes spin, and spinning takes time. Spacetime cannot accurately describe what happens inside of a black hole.

The birth of the universe has its own event horizon. At some point, the universe was so dense that it would have resembled a black hole to an outside observer. At our point in time, we are outside of that event horizon. Just like a black hole, there's a point where our ability to address points in spacetime fails when we try and address a point on the other side of that event horizon. Once again, spacetime cannot accurately describe what was happening when the Universe was that dense.

Will we one day be able to? I actually think it's possible, but to do so we have to abandon our common-sense ideas of how events relate to each other. Things like multi-dimensional super-strings are one approach to doing that- events can be specified with a larger coordinate system. But even as we build workable, mathematical descriptions of what happens on the other side of an event horizon, terms like "before" and "time" still won't make sense. We'll need highly abstract mathematical concepts to talk about them.

And unfortunately, our ability to experimentally confirm these models will always be bounded by the fact that the speed of light prevents us from peeking beyond an event horizon. Information can leak out of a black hole, but only the information that goes into it. Information about the black hole itself can't be seen, ever.
 
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