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Spaghettification electromagnetism

  1. Mar 30, 2012 #1
    I posted this question on another forum, and, the answers, thus far, have not really helped me out very much. So, I figured physics questions are best directed toward the 'physics guys'. Here is the text of my two posts. I feel like the problem probably lies with my extremely limited understanding of the subject, so, do not be concerned at all with the idea of hurting my feelings. If I am an idiot, I need to know that. :)


    In my own strange version of counting sheep the other night, a question occurred to me about what would happen if a person fell into a black hole. To picture the curvature of space/time, I imagine the universe as being sort of like a great big block of wood, and everything that moves in it has to follow the grain, with that ‘grain’ being caused by mass imbedded in the wood. I assume space to be quantized, and, each strip of grain in the wood being one unit in diameter. Everything moving through this goes to the next unit of space/time that is directly in front of it, so, in that sense, it is moving in a straight line, even though it appears to dip and curve from a different point of view. The curvature would be at it’s most extreme at the black hole. If my understanding is approximately correct, then, something with mass would be pretty much as close to the speed of light as it’s mass allows after it crosses the event horizon. After that, the ‘grain’ of space/time has sort of circled into a closed loop from which there is no escape. I don’t understand how the acceleration process could continue after having crossed the event horizon, since you are already traveling, literally, as fast as possible. I guess that the spaghettification thing would have to happen before one actually reached the event horizon? So, it would then be possible to actually observe this from a safe distance?



    "ibanezerscrooge - 29 March 2012 06:45 AM

    I love black holes (that does not sound right, lol)! Check out this video. I really like the way it is explained and the graphics are very good. I think this might help you think about it as it does me. Forgive me if you’ve seen it before."


    I did watch the video just to make sure that I hadn’t missed something important, which, sadly, is always a possibility. What he said was essentially what I thought he would say. And, he did say that the spaghettification thing would happen after crossing the event horizon, not before, which, to me, makes no sense at all. If an object is released at the outer edge of the earth’s gravitational well and falls to the surface, it will hit the surface at about 11 km/s, the escape velocity from the surface of the earth, assuming that it is sufficiently aerodynamic to reach that speed. Whatever the escape velocity is at a given distance from a center of gravity, that is how fast an object will be going that free falls in to that point. If an object free falls into a black hole, it would have to be traveling at near the speed of light right after crossing the event horizon, because that is the escape velocity at the event horizon. It would speed up very little, if any, from that point on. If one accepts that gravity isn’t really a force in the same sense as kinetic energy or electromagnetism, but rather, a curvature in space/time, more of a geometrical property, and, that there is a maximum speed at which something can travel through space/time, then, it follows that any additional ‘pull’ on an object would not express itself as more speed, but, rather, more mass, since mass and energy are the same thing. You would get a lot heavier, not stretched out because of your feet being closer to the center of gravity than your head. You’ve already hit the speed limit. I understand that the math for calculating escape velocities and other gravitational phenomena allow for infinitely higher escape velocities, but, in practise nothing can go faster than light to escape, and, nothing can fall in faster than the speed of light because of gravitational acceleration. This, to me, would suggest the possibility of a maximum possible amount of curvature in space/time, which would make sense, since, if there is no limit to how much space can be curved, that would have the possibility of violations of the uncertainty principle. If a particle is on a trajectory that curves in on itself more and more, and there is no limit to this inward spiral, eventually the both particle’s location and momentum could be known with very high precision. It is sitting right there, spinning in a very specific location. All of it’s momentum is now angular.

    And, that is when I fell asleep. I could be just as wrong as can be because of some information that I am totally unaware of, but, I just don’t see how that spaghettification thing could happen on the inboard side of the event horizon.
     
  2. jcsd
  3. Mar 30, 2012 #2
    Re: spaghettification

    Hi VeronicaS, welcome to Physics Forums!

    You're definitely on the right track on most of your thoughts / metaphors; but there is a good deal of confusion and misconception (as would be expected). Lets look at some details

    And kudos on an excellent, scientific attitude ;)

    This is an interesting and very non-conventional view of space-time, as your understanding develops it might start to fall apart... but maybe not. Note that we don't know if space is quantized or not---all accepted models assume it to be continuous.

    1) In general, things can enter the event horizon at an arbitrary velocity (between zero a c), but they do tend to enter very very quickly (i.e. close to c)
    2) There is no such thing as 'as-close to c as possible'. Reaching the speed of light is an asymptotic process (which never actually reaches c), but you can always go arbitrarily closer. Even though you may be traveling 1 MPH slower than the speed of light, you're still infinitely far from reaching the speed of light (i.e. it would require infinitely more energy, acceleration, etc etc).

    For the most part, spaghettification isn't anything inherently special about black-holes or general relativity. Its just an example of a 'tidal-force' which is actually the difference in force between one side of something and the other----just like the earth's tides. This effect can become very significant near black-holes. For example, near a stellar-mass black-hole, the force on one part of your body would be tremendously larger than on the other---stretching you out. The magnitude of this effect depends on your distance from the center of the black-hole. For a very massive BH (e.g. a super-massive BH), the tidal forces would only be significant once you were inside the event horizon. For a solar mass black-hole, it would be important well-outside the EH.

    There are some additional effects from general relativity specifically, which are always important near (but outside) the event horizon. These are much more subtle.





    This is only true for newtonian gravity. In GR it becomes more complicated, but as I said above, you keep accelerating until you reach the singularity, but you never pass the speed of light---even though the speed of light is the classical (i.e. newtonian) escape velocity at the event horizon.

    Unrelated note.... kinetic energy is not a force :P

    I don't understand your reasoning here.... but the end answer would probably be that we have no idea how to mix general relativity with quantum mechanics. We don't have an excepted theory of 'quantum gravity' (which would be that mix), and until we do - we don't really know whats up.

    Hope that helps!

    P.S. Being wrong about stuff doesn't make you an idiot---in fact, just thinking about these things, and having the chance to be wrong, proves the opposite.
     
  4. Mar 30, 2012 #3
    Re: spaghettification

    Thanks for the welcome. :) That 'block of wood' thing is just how I visualize what would otherwise be a pretty abstract concept. I'm pretty confident that, if I actually tried to develop some idea based on that as a legitimate model, I would soon be in trouble.

    I understand that it is not yet known whether space is quantized or not, and that pretty much every model that I've been able to get my mind around assumes that it is not. Since I haven't darkened the door of a classroom since I graduated from high school nearly twenty years ago, there are many things that I have trouble getting my mind around. But, this also gives me the freedom to imagine without consequence. I don't have to worry about doing 'important' work in the field. All that I have to do is figure out a way to have the universe make sense, and have my understanding of how things do what they do agree with the experiments that people do. I understand that relativity and quantum mechanics don't play well together, almost as if the universe has a different set of rules for little bitty stuff than it does for great big stuff. The idea that there are two different sets of rules is not one that I can easily get onboard with, though. There has to be a single set of rules, it's just that the actual, fundamental rules that everything operates by are not yet known. If space is, in fact, quantized, the universe makes a lot more sense to me. If space is not nothing, but, rather, something, then I don't see how there could not be a minimum unit of this 'something'. So, I start my mental ramblings from there.

    As far as this goes
    "This, to me, would suggest the possibility of a maximum possible amount of curvature in space/time...that would have the possibility of violations of the uncertainty principle.... eventually the both particle’s location and momentum could be known with very high precision.

    I don't understand your reasoning here.... but the end answer would probably be that we have no idea how to mix general relativity with quantum mechanics. We don't have an excepted theory of 'quantum gravity' (which would be that mix), and until we do - we don't really know whats up."

    My thinking on this is that, if space is continuous, and, if it is always possible to warp space a little more, no matter how much it is already warped, then it would be possible to twist space into an inward spiral which terminates in a single point. If a particle followed that inward spiral, it would end up at a point with no way out without reversing it's direction. It would therefore be possible to know both it's location and it's momentum with a high degree of accuracy. If space is quantized, it could be that the limit on how much space could be warped is something like an array of three of these units, each adjacent to the other two, so that the uncertainty principle would not be violated. Or, maybe some other value, but, a definite limit of some sort.

    The idea that I am bouncing around in my head is that things seem to make a lot more sense with limits placed on how small things can get and how warped space can become. These limits would have to be 'really small' and 'warped a whole bunch', but, there should be limits. It seems to me that this might also open a window to an explanation of inertia. What we have now appears to be merely a description. In continuous space, I would have no idea of where to even begin trying to develop an explanation of why things that are moving want to keep moving in a straight line. In quantized space there could possibly be some super-conductive characteristic to the individual units which causes them to eject matter with the same force they got hit with, or maybe some kind of wave characteristic or something. I could think of avenues of possibilities that might or might not pan out, but, it would be research moving towards an explanation rather than merely a description. By no stretch of the imagination am I a scientist, but, I am really, really curious about how stuff does the stuff that it does, and I thoroughly enjoy trying to figure things out. Questions are a lot more fun than answers.

    And, again, thanks for the welcome and the explanation. That did help clarify some things for me, and clarity is critical when you don't know much and are doing everything in your head. :)
     
  5. Mar 31, 2012 #4
    Re: spaghettification

    The classical analogy, while cliché, can certainly be useful. Consider balls rested on a taught sheet (or trampoline, or whatever). The sheet is a 2D representation of 3D space, while the fourth dimension that the sheet bends in (i.e. up an down) represents time. The sheet is flat in the absence of mass, but becomes distorted in and towards its presence. Locally, the sheet seems flat---even around objects---and things move (or think they move) in straight lines. The only hint that the surface is curved in a higher dimensional space is through detailed measures of straight lines in different places.

    Ah, I follow. That's exactly the concept underlying the 'singularity' at the center of a black-hole. The problem you mention is certainly one of them, and there are many (infinite density, infinite-or-zero temperature... etc etc), and the quantized solution is certainly a possibility.

    Unfortunately post-standard model theories are way out of my league, so I can't comment on what the hip things that people are thinking about are. I know quantized space(-time) is definitely something lots of people are interested in, and certainly make some sort of sense, based on quantum mechanics.
    Don't forget that physics can't really offer 'explanations' as apposed to descriptions---one can keep asking 'why?' indefinitely, and science inevitably runs out of answers, leaving eventually 'thats just the way the universe works'. Your inertia example is a good one, it would motivate why things tend to maintain their motion---but it begs the question of "why are those quantizations `super-conducting'?", and so on.
     
  6. Mar 31, 2012 #5
    Re: spaghettification

    The trampoline thing is kind of how I ended up at the block of wood thing. I thought about that, and had a bit of trouble translating it into a three dimensional image, so I thought of a trampoline with a bowling bowl on it and then layers of material following that configuration, added more and more layers to have multiple possible paths, some which hit the bowling ball, and the higher layers missing it. I realized that what I had constructed looked a lot like the grain in a board, so I just expanded my board to the size of the universe.

    I heard a series of lectures by Richard Feynman, and he went into an explanation of why modern physicists stick to descriptions rather than explanations, ( kind of ironic :) ) but, the sort of 'explanation' he was talking about was more the philosophical type, like 'nature abhors a vacuum', etc... That sort of explanation is pretty useless because it answers no questions and does nothing to help predict what should come next. This reasoning is something that I happily agree with, but, it is also obvious that explanations of a different sort do answer questions and are extremely useful for predicting 'next'. Newton gave us a description of what gravity does, and Einstein gave us an explanation of why gravity does what it does, and his explanation answered the questions about Mercury's orbit, and predicted that the apparent position of stars would shift by a specific amount during a solar eclipse. It also answered a whole bunch of other questions, and predicted a whole bunch of other stuff, but, those examples should be sufficient to make the point that physicists do indeed look for explanations instead of settling for descriptions, and I am pretty comfortable with the idea that Dr. Feynman would agree with that. It is true that one could get caught in that 'perpetual why' trap, but, on exploring questions like inertia, or black holes, that would be an extremely useful and interesting venture. A person would have to figure out a lot of other stuff before offering a plausible explanation of inertia that could be demonstrated and independently verified.

    I love this stuff. :)
     
  7. Apr 1, 2012 #6
    Re: spaghettification

    I agree ;)
     
  8. Apr 5, 2012 #7
    Re: spaghettification

    I think spaghettification is a perfect way to describe a black hole. A black hole is a dipolar noodle. As the galaxy goes around the noodle (it will never actually enter the black hole) it will slide (spiral) along the noodle pole until one the following: 1) Galaxy crashes into another galaxy and they wipe each other out (maybe merge) OR 2) Galaxy does not hit anything else and eventually it will reach the event horizon and the galaxy's polarity switches (as do all planets in that galaxy) and so the galaxy then moves away from the black hole noodle (as would polarity). So in other words, light nor matter will ever enter the black hole noodle. It will bounce away or slide along the polarity until it flips. Then race away relative to the size of the flip and mass. This effect makes distances between galaxies appear to be accelerating away.

    The dipolar black hole noodle determines the size of the galaxy.

    All these dipolar black hole noodles are innertwined. When the black hole noodles merge is when they have aligned their polar opposites.

    This explains everything.

    I hope this helps!
    -Manvegas
     
  9. Apr 5, 2012 #8
    Re: spaghettification

    Welcome to PhysicsForums Manvegas.
    Please consult the Physics Forums Rules, especially the section concerning overly speculative posts.

    But congrats on one of the craziest responses I've seen here.
     
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