Conundrum thinking about crossing an Event Horizon

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  • #26
Ibix
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Well your saying that light coming towards a black hole is blue shifted. If this is the case then some of it would escape and appear at the edge of a black hole in an actual observation?
For an observer hovering near the hole, light is blueshifted. But it would be redshifted by the same amount as it climbs back out of the hole's gravitational field. So stars observed past a (non-rotating) black hole are neither red nor blue shifted if you are far from the hole. If you are near the hole they may be blueshifted if you are hovering or redshifted if you are moving fast enough.
I am rusty but if you let v exceed c:
1/((1-(v^2/c^2))^(1/2))
The result is imaginary.
But as already noted, nothing is exceeding c.
 
  • #27
Ibix
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If there were a pinging beacon outside the EH (say in some stable orbit around the black hole) that the traveler was monitoring, will the ping frequency combined with knowledge of the beacon orbit and the mass of the black hole tell the traveler when they have crossed the EH? I am thinking, perhaps incorrectly, that the traveler will observe the ping frequency increasing as they go deeper into the gravity well.
The frequency will decrease, as per my correction in #24 to my claim in #12, and discussion with PeterDonis.
 
  • #28
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You don't know if the rules apply inside a black hole. And what about tachyons? Some people think they exist. Quantum entanglement?
 
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  • #29
256bits
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"My calculations suggest stars are blueshifted for an infalling observer." - Ibex

Consider two free falling objects, one after the other. As they fall, the distance between them constantly increases due to the first object always falling faster than the second. To the first object, the second is receding from it, so it would appear to be red shifted. To a stationary observer, yes, the stars would appear blueshifted, but not to an infalling observer.
Please clarify.
If the object is released from infinity, and the light is released from a source at infinity, would not both be in free fall, so no red shift nor blue shift would be noted in this case.
 
  • #30
Ibix
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You don't know if the rules apply inside a black hole. And what about tachyons? Some people think they exist.
Note that this site is for discussion of mainstream science only. If you want to discuss alternate models of black hole interiors, please provide a peer-reviewed reference for the model you wish to discuss, as per site rules. I'm afraid that "the rules don't apply" and applying the Lorentz gamma factor (one of those very rules) seem contradictory to me, so I need to see such a reference before I can comment meaningfully.
 
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  • #31
PeterDonis
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You don't know if the rules apply inside a black hole.
If the rules don't apply, we can't say anything at all, which makes discussion pointless. So as a basis for discussion here, we're assuming the same rules apply inside a black hole that apply outside. No other basis for discussion is practical.

And what about tachyons? Some people think they exist. Quantum entanglement?
All of these are irrelevant to this discussion. Please stick to the topic of the thread.
 
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  • #32
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Close mindedness makes discussion pointless also.
 
  • #33
berkeman
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Close mindedness makes discussion pointless also.
Agreed. (yours, not ours). Thread is closed.
 
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