There are some cool "practical" consequences like building time machines. But you need some serious civil engineering equipment: First take a mass the size of

There are some cool "practical" consequences like building time machines. But you need some serious civil engineering equipment: First take a mass the size of a star. Squeeze it into a thin really really long cylinder, make it rotate very fast ... and boom! You can travel back to the day you created it. [0] http://adsabs.harvard.edu/abs/1976PhDT........61T http://adsabs.harvard.edu/abs/1976PhDT........61T [1] https://en.wikipedia.org/wiki/Tipler_cylinder https://en.wikipedia.org/wiki/Tipler_cylinder