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).
i know that godel's metric cant work becuase the universe does not rotate,what does kerr's metric need to obtain a ctc?
tipler's time machine have ctc's,but only if it's infinintly long?, also a ctc would be in the singulartiy?
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.
ya it says tippler's time machine would only go back in time if it were infinintly long,on the wiki page.
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.
Black Holes evidence, is indirect. Anything goes, at the moment. (Yeh, i read it.) Please Register or Log in to view the hidden image!
You're tired! Please Register or Log in to view the hidden image! 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.
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. Please Register or Log in to view the hidden image!
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.