threeright Posted March 28, 2017 Share Posted March 28, 2017 (edited) Okay, most sources say that once you get past the event horizon, you will be ripped apart by the gravity and die. Yet, they also say that once you pass event horizon, every direction leads to the singularity. This doesn't make sense. If every direction leads to the singularity and you get pulled toward the singularity then you are getting pulled towards the singularity in every direction... Wouldn't the forces cancel out? Also, since the singularity is infinitesimally small, wouldn't it take you forever to actually get to the singularity as every part of you is approaching that which is infinite? Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
Phi for All Posted March 28, 2017 Share Posted March 28, 2017 Does it help if you picture gravity warping spacetime so drastically that there simply are no paths for anything to escape? There's just a single force, gravity, so there's nothing to cancel out. Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) Yes, there is no path to escape, because all path leads to the singularity. Thus, every direction leads towards singularity. So, you are getting pulled towards singularity in every direction. But, if you get pulled towards the singularity in every direction, they should cancel out. Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
swansont Posted March 28, 2017 Share Posted March 28, 2017 What rips you apart is the tidal force, i.e. the difference in gravity acting on different parts of your body. Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) What do you mean? If all paths lead you towards the singularity, then any direction you face should also lead you towards the singularity. The singularity should be the same distance away from you in every direction because every direction leads towards it. If that's the case, then the pull towards the singularity should be in every direction by exactly the same amount Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
zztop Posted March 28, 2017 Share Posted March 28, 2017 Yes, there is no path to escape, because all path leads to the singularity. Thus, every direction leads towards singularity. So, you are getting pulled towards singularity in every direction. But, if you get pulled towards the singularity in every direction, they should cancel out. The "ripping apart" happens BEFORE the object crosses the event horizon. A picture will help. Link to comment Share on other sites More sharing options...
Strange Posted March 28, 2017 Share Posted March 28, 2017 Interesting question. A couple of thoughts... Although all paths lead to the singularity, they may not all have the same length - and therefore not the same gravitational force. Inside the singularity, space-time is so curved that the singularity is in your future rather than ahead of you. Which is why it can't be avoided. Maybe tidal forces are only present outside the event horizon. I don't know. Link to comment Share on other sites More sharing options...
zztop Posted March 28, 2017 Share Posted March 28, 2017 Maybe tidal forces are only present outside the event horizon. I don't know. yes Link to comment Share on other sites More sharing options...
Strange Posted March 28, 2017 Share Posted March 28, 2017 yes Lucky guess! (Based on the second point I made.) Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) Interesting question. A couple of thoughts... Although all paths lead to the singularity, they may not all have the same length - and therefore not the same gravitational force. Distance from your head to the singularity should be different from the distance from your foot to the singularity. However... if all direction leads to the singularity then singularity will pull your head in every direction towards it. It will also pull your feet in every direction towards it. So the net force on your head should equal net force on your feet. You should be able to generalize this so that it applies to every point on your body. It seems like the tidal force should only be felt before you enter the event horizon, but not after... Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
MigL Posted March 28, 2017 Share Posted March 28, 2017 There is no difference in the way a BH acts gravitationally from an equivalent mass which is not a BH. Tidal forces exist within the event horizon. As a matter of fact, for a galactic center BH ( millions of solar masses ), the density required for gravitational collapse is equivalent to that of water, and you would not feel any tidal effect until you've passed through the event horizon and are well on your way to the ( possible ) singularity. What 'all possible paths lead to the singularity' means is that most paths are impossible once having passed the event horizon. The only available ( possible ) path left, leads to the singularity, and is usually stated as the only destination in your future is the singularity. 1 Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) There is no difference in the way a BH acts gravitationally from an equivalent mass which is not a BH. Tidal forces exist within the event horizon. As a matter of fact, for a galactic center BH ( millions of solar masses ), the density required for gravitational collapse is equivalent to that of water, and you would not feel any tidal effect until you've passed through the event horizon and are well on your way to the ( possible ) singularity. What 'all possible paths lead to the singularity' means is that most paths are impossible once having passed the event horizon. The only available ( possible ) path left, leads to the singularity, and is usually stated as the only destination in your future is the singularity. Yeah, I got that within event horizon, the only possible path is towards the singularity. As the space has been warped so much that traveling in any direction, forward, backwards, left, right, up or down, will get you closer to the singularity. If that is true, singularity should be pulling you towards it in every direction. So, I am having a hard time grasping how tidal forces will still exist Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
Strange Posted March 28, 2017 Share Posted March 28, 2017 Another curious thing is that if you free fall towards the singularity you will get there very quickly. If you try and avoid that, for example, by using your rocket engines to go in a different direction, you will actually get to the singularity sooner. (Don't ask me to explain why that is, but I was told it is the case by someone who can do the math.) 1 Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) Another curious thing is that if you free fall towards the singularity you will get there very quickly. If you try and avoid that, for example, by using your rocket engines to go in a different direction, you will actually get to the singularity sooner. (Don't ask me to explain why that is, but I was told it is the case by someone who can do the math.) By definition, within the event horizon, there is no "different direction". Every direction leads to the Singularity xD Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
MigL Posted March 28, 2017 Share Posted March 28, 2017 Again, there are NO other directions. The only POSSIBLE direction leads to the 'future', which is the singularity. And it is possible to have tidal forces in one direction. A simple way to look at it is when the gravitational differential across 6 ft is large enough to give a measurable difference, you will feel a 'tearing' force between your head and feet. Link to comment Share on other sites More sharing options...
Strange Posted March 28, 2017 Share Posted March 28, 2017 By definition, within the event horizon, there is no "different direction". Every direction leads to the Singularity xD You are still in three-dimensional space, so there are still three orthogonal directions. Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) You are still in three-dimensional space, so there are still three orthogonal directions. I know, they all lead to the Singularity MigL, the problem isn't that there's only one direction, problem is that EVERY direction leads to the Singularity. Edit: mistyped xP Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
Strange Posted March 28, 2017 Share Posted March 28, 2017 (edited) I know, they all lead to the event horizon None of them lead to the event horizon! They all lead to the singularity. (Actually, maybe not orthogonal but ...) Edited March 28, 2017 by Strange Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 None of them lead to the event horizon! They all lead to the singularity. (Actually, maybe not orthogonal but ...) Mistyped xP Link to comment Share on other sites More sharing options...
Delta1212 Posted March 28, 2017 Share Posted March 28, 2017 Another curious thing is that if you free fall towards the singularity you will get there very quickly. If you try and avoid that, for example, by using your rocket engines to go in a different direction, you will actually get to the singularity sooner. (Don't ask me to explain why that is, but I was told it is the case by someone who can do the math.) On which side of the event horizon? Link to comment Share on other sites More sharing options...
Strange Posted March 28, 2017 Share Posted March 28, 2017 (edited) On which side of the event horizon? Once within the event horizon. Edited March 28, 2017 by Strange Link to comment Share on other sites More sharing options...
Delta1212 Posted March 28, 2017 Share Posted March 28, 2017 Once within the eH. In which case, yes, all directions lead to the singularity, so if you speed up, no matter what direction you accelerate in, you are accelerating towards the singularity and will reach it sooner. Link to comment Share on other sites More sharing options...
threeright Posted March 28, 2017 Author Share Posted March 28, 2017 (edited) In which case, yes, all directions lead to the singularity, so if you speed up, no matter what direction you accelerate in, you are accelerating towards the singularity and will reach it sooner. The point of the thread is the question of whether or not the force of the Singularity will cancel itself out once past the event horizon. Because if every direction leads to Singularity, then Singularity will pull you from every direction. Edited March 28, 2017 by threeright Link to comment Share on other sites More sharing options...
zztop Posted March 28, 2017 Share Posted March 28, 2017 (edited) The point of the thread is the question of whether or not the force of the Singularity will cancel itself out once past the event horizon. There is no such thing as "the force of the Singularity", so your questions are ill-posed. Because if every direction leads to Singularity, then Singularity will pull you from every direction. Did you get the part where the "spaghettification" due to tidal forces happens OUTSIDE the event horizon? Edited March 28, 2017 by zztop Link to comment Share on other sites More sharing options...
Phi for All Posted March 28, 2017 Share Posted March 28, 2017 The point of the thread is the question of whether or not the force of the Singularity will cancel itself out once past the event horizon. Because if every direction leads to Singularity, then Singularity will pull you from every direction. This is the part that's hanging you up. There's no canceling effect if the pull from every direction is towards a single direction, and if it is a singularity at the center, it's dimensionless. Maybe tidal forces are only present outside the event horizon. I don't know. yes Tidal forces exist within the event horizon. Can someone clear up this conflict? Link to comment Share on other sites More sharing options...
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