Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Creating black holes through relative motion

  1. Aug 18, 2009 #1
    My question is threefold, the second is based on the premise that the first is true, and the third is based on the other two.

    1. As relative velocity increases, mass also increases, correct? In this case, could you accelerate away from an object to a velocity fast enough to make its schwartzchild radius larger than the object, creating a black hole?

    2. Would this object then collapse in upon itself so that if you slowed down to zero speed relative to the object, it would still be a black hole?

    3. Will the outward acceleration of the universe ultimately result in the formation of black holes due to the very high velocity of objects relative to one another?

    EDIT: one factor I did not account for, in retrospect, is the deformation of an object at high speeds-- I read a little bit about this, but I don't know exactly where to go with it. Black holes have no hair, right?
  2. jcsd
  3. Aug 18, 2009 #2
    If the energy used to accelerate the object was already stored in the system to begin with, then that system was already a black hole to begin with. If the energy used to accelerate the object was added from some external source, then the system would become a black hole simply because you poured a massive amount of energy into it.

    Kinetic energy is not "in" the moving object. Its "in" the relative motion of two or more objects. Consider that you cannot extract kinetic energy from an object that happens to be moving relative to you unless you use some machine to extract it, and that machine must connect to the object AND connect to a massive object stationary to you.

    No, because of the previous answers.
  4. Aug 18, 2009 #3
    What if the energy was from a rocket, stored in chemical potential energy? Then the kinetic energy to generate the motion would be coming from an internal source, so the total energy of the system would be constant, wouldn't it?

    And then if you sustained that velocity, wouldn't the black hole collapse into a singularity or something?

    I think you may have answered my question-- but I guess I don't exactly understand.
  5. Aug 21, 2009 #4
    A black hole is a singularity, we just call it a black hole because we can't see it with the naked eye.

    From Schwartzild's theory, yes, you can in theory create a black hole, however you would need immense mass and go close to/faster than the speed of light to make it able to collapse into a singularity.

    If an object turns into a singularity, then it would remain a singularity, no matter what speed the observer holds; when you see a tree, even if you run around the tree as fast as you can, you will still see a tree, however you get very dizzy.

    Unless all objects in space could accelerate faster than the speed of light, then yes, everything in the universe would be able to collapse into a singularity, however, this is so unlikely to happen as if Bill Gates were to die right now and pick me out of a random line of 6 billion people to recieve all his money and all of his corperations.
  6. Aug 21, 2009 #5
    1. Black hole IS NOT a singularity
    2. Relative motion DOES NOT create black holes
    For more info, check the difference between the invariant and the relativistic mass
  7. Aug 21, 2009 #6
    Ah right I mis-spoke, I meant to say wouldn't the object collapse into a black hole, not wouldn't the black hole collapse into a singularity. WHoops

    Anyway, I refined my question and did a google search for "relativistic mass and schwartzchild radius" and came away with a few pieces of literature.
    I guess you can't take relativistic mass and use it in newtonian physics :P I think that's where I went wrong.
    Anyway thank you all for your help.
  8. Aug 21, 2009 #7


    User Avatar
    Science Advisor

    Here's what I get:
  9. Aug 21, 2009 #8
    That's because I mis-spelled schwarzschild in my post.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook