Time Travel

Traveling forward in time is simple. You can travel close to light speed, fall asleep locked in a closet, or just sit there (if you're satisfied with your current rate of travel which is one second per second). Backward is another story. The logical problems can be solved if the state of the universe is "saved off" at periodic intervals like a hardDrive backup. Then, when you go to a previous state, all of the states after the destination state are blown away and, if you travel forward again, it's just like locking yourself in a closet. So, the future world you arrive at will only be the same as the one you left if every single coin flip and other random event turns out *exactly* the same as they had in the world you remembered.

This leaves the physical problem of conservation of mass. If you go back in time, the destination universe suddenly has more mass (you are added). This can be fixed by relativity, but the amount of energy to account for something big (like a person) is far too much for any conceivable device to generate. You also need to absorb the energy released by your disappearance in the present. However, something tiny, like a subatomic particle, could be managed this way. Information, for example, in the form of one spinning quark per bit (spin direction = bit value) could be sent. Say, 32 (enough to win the lottery) would be perfectly reasonable for a modern device.

Of course, the problem of random events reoccurring still exists, but if you minimize the amount of time it has to travel backward and the influence of those who know the result, you could probably still win it (though it may take a few tries).