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<blockquote data-quote="freyar" data-source="post: 5313191" data-attributes="member: 40227">It seems like maybe some people are confusing the time measured by the person falling into the black hole and the time measured by the observers who manage to stay outside.&nbsp; You might find the <a href="http://en.wikipedia.org/wiki/Penrose_diagram" target="_blank">Penrose diagrams</a> to be helpful.&nbsp; The idea of a Penrose diagram is that light rays make 45-degree lines (so massive objects follow trajectories that are always more vertical than 45 degrees), and the ones we'll look at have the angular directions suppressed, just showing radius from some center and time.&nbsp; As an example, look at the diagram for Minkowski spacetime -- the normal flat spacetime of special relativity with trivial gravity -- it's at the top of the page. You'll notice that the sides of the diamond are &quot;lightlike infinity&quot; (all light rays end up on these lines), &quot;spacelike infinity&quot; at the two left-right points of the diamond (where you are if you are an infinite distance away from the center at a fixed finite time), and &quot;timelike infinity&quot; at the top-bottom points (where you are when you're infinitely far into the future or past but at a finite distance from the &quot;center&quot;).Now look at the second diagram and check out the example for the basic black hole (labeled Static &quot;Grey&quot; Wormhole in the diagram) in the second diagram.&nbsp; The person falling into the black hole passes the event horizon and hits the timelike singularity in a finite amount of time according to their watch.&nbsp; However, if they're sending out light pulses as they fall in, you can trace out those 45-degree lines.&nbsp; You'll see that no one can see the last pulse emitted along the horizon unless they're at timelike infinity -- one of the points at the corner of the timelike singularity adjoining the &quot;our universe&quot; diamond.&nbsp; The Real Black Hole is also relevant; the star is collapsing, and eventually it forms an event horizon -- we observers only actually see the event horizon swallowing the star at an infinite time in the future.A note on the Electrically Charged And/Or Rotating Wormhole: the wormhole tends to collapse if you put any actual mass through it, so you can't really get through to the other universes.</blockquote>

[QUOTE="freyar, post: 5313191, member: 40227"] It seems like maybe some people are confusing the time measured by the person falling into the black hole and the time measured by the observers who manage to stay outside. You might find the [url=http://en.wikipedia.org/wiki/Penrose_diagram]Penrose diagrams[/url] to be helpful. The idea of a Penrose diagram is that light rays make 45-degree lines (so massive objects follow trajectories that are always more vertical than 45 degrees), and the ones we'll look at have the angular directions suppressed, just showing radius from some center and time. As an example, look at the diagram for Minkowski spacetime -- the normal flat spacetime of special relativity with trivial gravity -- it's at the top of the page. You'll notice that the sides of the diamond are "lightlike infinity" (all light rays end up on these lines), "spacelike infinity" at the two left-right points of the diamond (where you are if you are an infinite distance away from the center at a fixed finite time), and "timelike infinity" at the top-bottom points (where you are when you're infinitely far into the future or past but at a finite distance from the "center"). Now look at the second diagram and check out the example for the basic black hole (labeled Static "Grey" Wormhole in the diagram) in the second diagram. The person falling into the black hole passes the event horizon and hits the timelike singularity in a finite amount of time according to their watch. However, if they're sending out light pulses as they fall in, you can trace out those 45-degree lines. You'll see that no one can see the last pulse emitted along the horizon unless they're at timelike infinity -- one of the points at the corner of the timelike singularity adjoining the "our universe" diamond. The Real Black Hole is also relevant; the star is collapsing, and eventually it forms an event horizon -- we observers only actually see the event horizon swallowing the star at an infinite time in the future. A note on the Electrically Charged And/Or Rotating Wormhole: the wormhole tends to collapse if you put any actual mass through it, so you can't really get through to the other universes. [/QUOTE]

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