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E is for Event Horizon
Jul. 4th, 2008 12:25 pmInfinite Space! Infinite Terror! The year is 2047 and... *shut yo mouth!* But I'm talkin' 'bout physics. *we can dig it!*
An event horizon is a spacetime boundary often associated with (but not limited to) black holes. Events happening within the boundary cannot reach the observer watching from beyond that boundary (on the outside, of course). Once an object crosses the event horizon, fuhgetaboutit. It will never be seen again.
So let's say Major Tom was approaching a black hole instead of just going for a spacewalk and getting lost. He's approaching the event horizon but hasn't crossed it yet.
GC: "Ground Control to Major Tom."
MT: "This is Major Tom to Ground Control. The event horizon looks really far away. And I think my spaceship knows which way to go."
GC: "Ground Control to Major Tom. No shit, sherlock. It's being sucked in by the black hole's groovitational pull. And, uhhh, the event horizon isn't that far away. We can all see it fine here and you're getting close, though it doesn't appear you've crossed it yet. How far out are you, man?"
MT: "I'm pretty far out."
GC: "That's pretty far out, man."
MT: "Tell my wife I love her very much."
GC: "She knows! Ground Control to Major Tom, your circuit's dead, there's something wrong. Can you hear me Major Tom?"
MT: "Here am I floating in my tin can. Far away from the event horizon."
GC: "We can't hear you. You didn't do something stupid like cross the event horizon, never to be heard again, did you? I mean seriously. You don't appear to have crossed the event horizon, but we can't see or hear you."
Mother: "Tommy?"
GC: "Who the hell said that?!"
Okay, okay... I got carried away. So anyhow... if Major Tom was entering the black hole slowly, say in a floating tin can of a spaceship insulated only by fancy tin foil, he would never observe himself crossing the event horizon. It would always seem far away to him. Ground Control, being the distant observer, would never actually really see Major Tom cross the event horizon, but they and several other distant observers at various unique positions could observe and verify what they perceive as a definite event horizon to be crossed.
It's pretty freaky, Bowie.
An event horizon is a spacetime boundary often associated with (but not limited to) black holes. Events happening within the boundary cannot reach the observer watching from beyond that boundary (on the outside, of course). Once an object crosses the event horizon, fuhgetaboutit. It will never be seen again.
So let's say Major Tom was approaching a black hole instead of just going for a spacewalk and getting lost. He's approaching the event horizon but hasn't crossed it yet.
GC: "Ground Control to Major Tom."
MT: "This is Major Tom to Ground Control. The event horizon looks really far away. And I think my spaceship knows which way to go."
GC: "Ground Control to Major Tom. No shit, sherlock. It's being sucked in by the black hole's groovitational pull. And, uhhh, the event horizon isn't that far away. We can all see it fine here and you're getting close, though it doesn't appear you've crossed it yet. How far out are you, man?"
MT: "I'm pretty far out."
GC: "That's pretty far out, man."
MT: "Tell my wife I love her very much."
GC: "She knows! Ground Control to Major Tom, your circuit's dead, there's something wrong. Can you hear me Major Tom?"
MT: "Here am I floating in my tin can. Far away from the event horizon."
GC: "We can't hear you. You didn't do something stupid like cross the event horizon, never to be heard again, did you? I mean seriously. You don't appear to have crossed the event horizon, but we can't see or hear you."
Mother: "Tommy?"
GC: "Who the hell said that?!"
Okay, okay... I got carried away. So anyhow... if Major Tom was entering the black hole slowly, say in a floating tin can of a spaceship insulated only by fancy tin foil, he would never observe himself crossing the event horizon. It would always seem far away to him. Ground Control, being the distant observer, would never actually really see Major Tom cross the event horizon, but they and several other distant observers at various unique positions could observe and verify what they perceive as a definite event horizon to be crossed.
It's pretty freaky, Bowie.
