In order to detect a certain kind of neutrino, the detector must be something like the size of the moon. Using such a detector, if one fired neutrinos through the core of the earth, you could cause time travel. I'm obviously missing something out, but I can't remember it. Thanks to some fiddly bit of physics, the people at the south pole might find the particles turn up before the people at the north pole have sent them. It might have to do with the earths magnetic field. Also, in order to make a wormhole and make it stable, and large enough for a spaceship to go through, you'd need electromagnets each the size of saturn. =/