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Author Topic: Communicate through the event horizon of a black hole by push/pulling on space time?  (Read 3058 times)

Offline rvt

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let's say you drop over the event horizon of a black hole. You cannot communicate back anymore using 'conventional' techniques because space is traveling faster then the speed of light (as how I currently understand the event horizon).

Now, let's say you bring some sort of device, perhaps be a gravitational wave generator that allows you to 'push/pull' on space-time, so you bring out your good old morse code book and operate the device based on morse code.. pull pull pull push push push pull pull pull.

Would you then be able to communicate through the event horizon of a black hole if on the other site somebody sit's with a detector that can detect disturbances in space/time and decode your morse code message?



 

Offline jeffreyH

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Offline Bill S

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Quote
Would you then be able to communicate through the event horizon of a black hole if on the other site somebody sit's with a detector that can detect disturbances in space/time and decode your morse code message?

Hi rvt, are you talking about communicating from outside in, inside out or in both directions?
 

Offline JohnDuffield

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let's say you drop over the event horizon of a black hole. You cannot communicate back anymore using 'conventional' techniques because space is traveling faster then the speed of light (as how I currently understand the event horizon)...
It isn't travelling faster than light. A gravitational field alters the motion of light and matter through space, it doesn't suck space in. Unfortunately there are some cosmologists who talk about the black hole "waterfall analogy". I'm afraid it's totally wrong and it's badly misleading.
 

Offline rvt

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Bill,

inside out. But I guess that would be the same as outside in...

John,
thank's for that information, I need to update my understanding :)
 

Offline PmbPhy

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No.

re - "because space is traveling faster then the speed of light (as how I currently understand the event horizon).
"

Is wrong. You can't speak of space as moving. That's what relativity is all about.
 

Offline evan_au

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Quote from: rvt
communication... inside -> out.
Gravitational waves only travel at the speed of light. But the escape velocity of a black hole exceeds the speed of light, so gravitational waves can't escape either.

Quote from: rvt
But I guess that would be the same as outside -> in
Information & matter can easily travel from outside the event horizon to inside the event horizon (it's unknown how garbled they would be after they cross the event horizon).
Neither matter or information can go from the inside of the black hole to the outside (as far as we know), so it is quite asymmetric.
 

Offline jeffreyH

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Quote from: rvt
communication... inside -> out.
Gravitational waves only travel at the speed of light. But the escape velocity of a black hole exceeds the speed of light, so gravitational waves can't escape either.

Quote from: rvt
But I guess that would be the same as outside -> in
Information & matter can easily travel from outside the event horizon to inside the event horizon (it's unknown how garbled they would be after they cross the event horizon).
Neither matter or information can go from the inside of the black hole to the outside (as far as we know), so it is quite asymmetric.

It has not been established how fast gravitational waves travel.
 

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