Can a beam entering a black hole be used to communicate with the outside world?

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Discussion Overview

The discussion revolves around the feasibility of using a beam entering a black hole to communicate with the outside world. Participants explore theoretical scenarios involving the manipulation of the beam and the implications of black hole physics, including the nature of event horizons and quantum entanglement.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions the behavior of a steel beam as it enters a black hole, specifically regarding its ability to communicate with the outside world while manipulating the beam after crossing the event horizon.
  • Another participant argues that the beam cannot be considered a truly rigid object, suggesting that it is made of point particles that would interact through fundamental forces, complicating any communication attempts.
  • A different viewpoint explains that while the beam may be twisted, the event horizon will approach the observer at the speed of light, making it impossible for any signal from the manipulation of the beam to reach the outside world due to the event horizon outpacing the signal.
  • A participant introduces the idea of using entangled particles, questioning the implications of measuring one particle inside the black hole on its entangled counterpart outside.
  • Another participant asserts that even in flat space-time, entanglement cannot be used to transmit information, implying limitations on the proposed communication method.

Areas of Agreement / Disagreement

Participants express differing views on the possibility of communication through the beam and the implications of quantum entanglement, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

The discussion involves complex concepts such as the nature of rigidity in materials, the behavior of signals in the context of black holes, and the principles of quantum entanglement, which may depend on specific definitions and assumptions not fully explored in the thread.

cragar
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I'm not sure if this the right place to post this . But suppose I have a long steel beam entering a black hole and I am at the leading end entering the black hole and we just past the event horizon. Now I try to rotate the beam, What will happen to the beam outside the event horizon. Or suppose I strap a rocket to it and fire it towards the center of the black hole increasing the beams acceleration towards the event horizon . And could I use this to communicate with the outside world. And let's assume that the black hole is pretty big and tidal forces are minimal so it doesn't rip me apart. Electrical interactions may prevent me from interacting with the beam outside of the black hole. Any input will be much appreciated.
 
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The beam cannot be a truly rigid object and therefore must be composed of point particles. These particles will interact via normal fundamental forces that hold the beam as a whole together. Imagine your beam is a 1 particle-wide string. The event horizon, in some frame of reference, dissects the beam. Because the particles are points and have 0 dimension, the event horizon line must be between two points in the beam; one is below the horizon, one is above. Any interaction between them will require interaction mechanics that transmit faster than light.

Extrapolate to beams with larger widths.
 
What will basically happen is this. You'll be in apparent free fall, and the event horizion will be approaching you at the speed of light, because it's a "null surface". You can consider the event horizon to be marked by "trapped light" if that makes it easier to understand, so you can think of this trapped light as approaching you at 'c', just as any other light does.

So, you'll twist the beam, and the twist will propagate outwards at some velocity less than the speed of light - for any realistic material known, much less than the speed of light.

Because the speed of sound is less than 'c', the event horizon will outrace any such signal you try to send by twisting or pulling, or otherwise manipulating the beam.
 
Ok thanks for your answers, What if I have two entangled particles one inside the BH and one outside, and I measure the spin on the one inside what will happen to the particle outside.
 
Even in flat space-time you can't use entanglement to send information.
 

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