Is it possible to travel in time?
There’s nothing in current physics that absolutely precludes it, however, the amount of energy it would take to do so would be enormous. Something on the order of the mass of the known universe to go back a few milliseconds, last I read.
We are traveling through time. It is just forward though time at a semi predictable way. As for backward through time, with our current knowledge no.
Also you can also search the message board and you will find hundreds of thread on this subject.
Cecil’s column on the subject: Is time travel possible?