Wolv1's questions about causality and particles

Discussion in 'Physics & Math' started by Wolv1, Aug 25, 2008.

  1. Reiku Banned Banned

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    For a better set of words, some scientists believe you can enter a black hole that is large enough, and entered very carefully. Hawking now believes you can't enter a black hole, because your particles would be mangled, and then quantum tunneled out of the black hole, and back into spacetime. Some scientists don't even believe black holes exist. So you see, it is very difficult to have an absolute model, that we can say (is the correct one).
     
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  3. Wolv1 Banned Banned

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    i know that godel's metric cant work becuase the universe does not rotate,what does kerr's metric need to obtain a ctc?
     
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  5. Reiku Banned Banned

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    Not sure.
     
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  7. Wolv1 Banned Banned

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    tipler's time machine have ctc's,but only if it's infinintly long?, also a ctc would be in the singulartiy?
     
  8. Reiku Banned Banned

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    I had never heard of the ''infinite long'' part of the machine. I also was curious of this.

    A singularity, can be thought of a curve in spacetime: An infinite curvature to be correct.
     
  9. Wolv1 Banned Banned

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    ya it says tippler's time machine would only go back in time if it were infinintly long,on the wiki page.
     
  10. Reiku Banned Banned

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    Ok. It's just i had never heard of this. I never doubted Oli though.
     
  11. Reiku Banned Banned

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    I'm not sure how Tipler would ever get a time machine to extend into infinity. It's a bit of a cop-out in that respect, nothing but waisted mathematics.
     
  12. Reiku Banned Banned

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    Very dissappointed

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  13. Wolv1 Banned Banned

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    ya did you read about it?
     
  14. Wolv1 Banned Banned

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    but black hole's have evidence and ctc's dont?
     
  15. Reiku Banned Banned

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    Black Holes evidence, is indirect. Anything goes, at the moment.

    (Yeh, i read it.)

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  16. Wolv1 Banned Banned

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    so i read it right? that it has to be infinite? sorry a little tired.
     
  17. Wolv1 Banned Banned

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    that it has to be infinite?
     
  18. Reiku Banned Banned

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    You're tired!

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    I've been up practically all night worrying about a test today at collage :bawl:

    Yes, i am a bit dissappointed the machine he proposed, isn't exactly constructable. Not within our capabilities anyway, to make an infinitely extending time machine.
     
  19. Wolv1 Banned Banned

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    ya,it sucks it has to be infinite.you don't mind me asking what are you studying?
     
  20. Reiku Banned Banned

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    Physics, Chemistry, Biology and (now) Math.
     
  21. Guest254 Valued Senior Member

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    Any compact spacetime admits closed, timelike curves.

    Sketch proof: let \(I^+ (p)\) denote interior of the future lightcone of the point \(p\in M\). Use \(\tau = \{I^+(p)\, :\, p\in M\}\) as an open cover of \(M\), and since \(M\) is compact we may assume wlog that this cover is finite so \( \tau = \{ I^+(p_1), I^+ (p_2) , \ldots, I^+ (p_n)\}\). Also wlog assume that no \(I^+(p_i)\) is contained in some \(I^+ (p_j)\) (since we could just make a finer cover removing the unwanted open set). But because of this, it follows that \(p_1\) is not in \(I^+(p_i)\) for \( 2\leq i \leq n\), and so \(p_1\) is in \(I^+(p_1)\), hence there exists a closed timelike curve in \(M\).

    Awesome.

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  22. Wolv1 Banned Banned

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    but closed timelike curves arent real know to exist?
     
  23. Wolv1 Banned Banned

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    Wolv's questions about causality

    im doing research for my class and decided to do it on ctc's for my class in advanced physics and would like to know if they exist in the universe? i ask this because i get that closed timelike curves are real and other's that say they don't and would really like some help for my class.
     
    Last edited: Aug 27, 2008

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