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I'm not quite sure how do we start with a "probability to survive trip to the event horizon" and end up with a possibility to travel faster than light? What is

I'm not quite sure how do we start with a "probability to survive trip to the event horizon" and end up with a possibility to travel faster than light? What is that hyperspace the article talks about? How falling down the black hole would transport the object anywhere spatially? The only thing such a trip could be used for is to see the end of the universe. As every object getting near the event horizon experiences the time slowing down compared with the outside a person on board a ship could probably see stars going out etc as billions of years passed. The time slows down so much one could never "pass through" a black hole as reaching the singularity would require the time to stop. So as the ship approaches the singularity the black hole would get smaller and smaller as it evaporated during those billions of years until it eventually disappeared. However, a ship wouldn't survive the disappearance as when the black hole is getting smaller the tidal forces increase eventually ripping the ship to shreds.

mirimir 8y ago
Yes, TFA says nothing about what happens after surviving the fall. But from Burko and Khanna (2019) I get this: > The fate of an astronaut who falls into a black hole depends not just on the latter’s properties (such as the intrinsic parameters, i.e., the mass and spin angular momentum, and the external perturbation fields) but also on the former’s worldline. ... However, astronauts with positive energy and low angular momentum (including counterrotating ones) arrive at the outgoing leg of the black hole’s inner horizon ("outgoing inner horizon", henceforth, OIH). > The properties of spacetime at the OIH have been proposed to be those of an effective shock wave singularity. Specifically, it was proposed in [2] that daughters of a family of free-falling astronauts whose geodesics intersect with the OIH, and who are separated only by time translations (and labeled by the advanced time values at which they cross the event horizon (EH) [symbols]) experience a change of order unity in typical metric perturbations, and that these changes occur over a lapse of proper time that drops like [symbols] with increasing [symbols], where [symbols] is the surface gravity of the OIH. Sufficiently late-falling daughters therefore experience an effective shock wave singularity, the Marolf-Ori singularity ("outflying singularity"). I have no clue what that means. Anyone? 0) Burko and Khanna (2019) The Marolf-Ori singularity inside fast spinning black holes, https://arxiv.org/pdf/1901.03413.pdf https://arxiv.org/pdf/1901.03413.pdf
Balgair 8y ago
So, there's a lot of work that has been done on this. Generally there is a difference between large and small black holes. With the smaller ones, tidal forces rip you apart down to quarks and you die. With larger ones, tidal forces aren't as crazy (they are still totally crazy though) and you sail right into the event horizon. It may be survivable. As for the time distortion: Yes, you see the end of the universe regardless of the black hole size. Yet, your clock continues to tick along just fine and you still fall in. Per our current understanding of physics, you get to see everything in the universe blue shift to infinity. In smaller black holes, since the Lorenz transform is so curved, all of space gets warped to directly in front of you, all the incoming radiation gets blue shifted to infinity. Essentially, every quark and electron gets blasted by pure radiation of infinitely small frequency. Think standing in front of a train in a dark tunnel with a bright light on the front. For larger black holes the Lorenz transform is less curved, so the cosmic Train Collision happens closer to the event horizon; but you still get blasted. (Note: I don't actually know if this is due to the Lorenz transform, but the best way to get a right answer on the internet is to give out the wrong answer :) ) If you are thinking that none of this makes sense and are saying "yes, but what about..." then you are thinking correctly. Black holes are very poorly understood and we're just at the beginning of trying to figure them out. One very important ratio to remember is: 5 : 20 : 75 . In the universe, everything that you are made of, all the matter, is only 5% of our known universe and most of that matter is locked up in stars. We're actually only a very small fraction of the universe. Dark matter is ~20% of the stuff in the universe. About all we currently know about dark matter is that it falls down. Does it have a temperature? No clue. Does it interact with matter? More data is needed. Does it interact with itself? We haven't any idea, would you like more tea? Dark matter is ~4x the amount of stuff we are, and we haven't a clue what it does. That said, Dark Energy is ~75% of the stuff in the universe and it ... falls up? Honestly, we're completely lost. We have no idea how it works, we just know the universe is flying away from itself and it's gas pedal is firmly glued to the floor. We haven't any remotely serious idea how to probe it outside of looking at galaxies and hoping we get lucky and see something funny. So, before we get all high and mighty and try to think we have any idea what is going on in a black hole, we've got to figure out what the other 95% of the universe is doing, as it's very likely to have really important things going on. Hyperspace? I mean, sure, why not? It's just about as strange a thing as Dark Energy is. So, I think the consensus is that: More research funding is needed.

mirimir 8y ago

Yes, TFA says nothing about what happens after surviving the fall. But from Burko and Khanna (2019) I get this: > The fate of an astronaut who falls into a black hole depends not just on the latter’s properties (such as the intrinsic parameters, i.e., the mass and spin angular momentum, and the external perturbation fields) but also on the former’s worldline. ... However, astronauts with positive energy and low angular momentum (including counterrotating ones) arrive at the outgoing leg of the black hole’s inner horizon ("outgoing inner horizon", henceforth, OIH). > The properties of spacetime at the OIH have been proposed to be those of an effective shock wave singularity. Specifically, it was proposed in [2] that daughters of a family of free-falling astronauts whose geodesics intersect with the OIH, and who are separated only by time translations (and labeled by the advanced time values at which they cross the event horizon (EH) [symbols]) experience a change of order unity in typical metric perturbations, and that these changes occur over a lapse of proper time that drops like [symbols] with increasing [symbols], where [symbols] is the surface gravity of the OIH. Sufficiently late-falling daughters therefore experience an effective shock wave singularity, the Marolf-Ori singularity ("outflying singularity"). I have no clue what that means. Anyone? 0) Burko and Khanna (2019) The Marolf-Ori singularity inside fast spinning black holes, https://arxiv.org/pdf/1901.03413.pdf https://arxiv.org/pdf/1901.03413.pdf

Balgair 8y ago

So, there's a lot of work that has been done on this. Generally there is a difference between large and small black holes. With the smaller ones, tidal forces rip you apart down to quarks and you die. With larger ones, tidal forces aren't as crazy (they are still totally crazy though) and you sail right into the event horizon. It may be survivable. As for the time distortion: Yes, you see the end of the universe regardless of the black hole size. Yet, your clock continues to tick along just fine and you still fall in. Per our current understanding of physics, you get to see everything in the universe blue shift to infinity. In smaller black holes, since the Lorenz transform is so curved, all of space gets warped to directly in front of you, all the incoming radiation gets blue shifted to infinity. Essentially, every quark and electron gets blasted by pure radiation of infinitely small frequency. Think standing in front of a train in a dark tunnel with a bright light on the front. For larger black holes the Lorenz transform is less curved, so the cosmic Train Collision happens closer to the event horizon; but you still get blasted. (Note: I don't actually know if this is due to the Lorenz transform, but the best way to get a right answer on the internet is to give out the wrong answer :) ) If you are thinking that none of this makes sense and are saying "yes, but what about..." then you are thinking correctly. Black holes are very poorly understood and we're just at the beginning of trying to figure them out. One very important ratio to remember is: 5 : 20 : 75 . In the universe, everything that you are made of, all the matter, is only 5% of our known universe and most of that matter is locked up in stars. We're actually only a very small fraction of the universe. Dark matter is ~20% of the stuff in the universe. About all we currently know about dark matter is that it falls down. Does it have a temperature? No clue. Does it interact with matter? More data is needed. Does it interact with itself? We haven't any idea, would you like more tea? Dark matter is ~4x the amount of stuff we are, and we haven't a clue what it does. That said, Dark Energy is ~75% of the stuff in the universe and it ... falls up? Honestly, we're completely lost. We have no idea how it works, we just know the universe is flying away from itself and it's gas pedal is firmly glued to the floor. We haven't any remotely serious idea how to probe it outside of looking at galaxies and hoping we get lucky and see something funny. So, before we get all high and mighty and try to think we have any idea what is going on in a black hole, we've got to figure out what the other 95% of the universe is doing, as it's very likely to have really important things going on. Hyperspace? I mean, sure, why not? It's just about as strange a thing as Dark Energy is. So, I think the consensus is that: More research funding is needed.