Travelling back, yes. Mr Einstein said so. Travelling forward, no. You cannot connect to an energy that does not yet exist.
Of course, why, only this morning I bumped into someone visiting from the future. Sounds a bit crap though, Charlton had just won the World Soccer League for the 35th time in a row and they still hadn't found flight MH370.
I can time travel without even meaning to. Dammit, it just happened again. And again. And again. And again. And again...
Did you know there is no such thing as now. It already went past. Dammit, it just went past again. And again. And again. And again. And again...
Time travel would be possible if you could exceed the speed of light, and that is deemed impossible so there's your answer.