Is it possible to make a Time Machine?
Building a time machine and time travelling are unsolved scientific problems. Some theories claim that it is possible and some deny.
In Wikipedia there is an article on time travelling http://en.wikipedia.org/wiki/Time_travel. In the end of article there are many links to relevant websites.
Here are few books about time machines and time travelling:
Davies, Paul: How to build a time machine. London : Penguin, 2002.
Le Poidevin, Robin: Travels in four dimensions : the enigmas of space and time. Oxford : Oxford University Press, 2003
Gott, J. Richard: Time travel in Einstein’s universe : the physical possibilities of travel through time. London : Phoenix, cop. 2002