I think that the only thing that is possible is to discuss what you might possibly mean by "traveling back in time". If you were to travel back in time, such travel would take place in your future. Therefore, you would be traveling into the future. If you were to travel into the past, you would be there. However, you were not there the previous time. Therefore, this would not be the past that was. Lastly, the entire universe has moved through time since the past. To travel into the past would require the entire universe to roll back to a previous stage, which I consider impossible under any circumstances, but certainly given that part of the entire universe, namely you, would not roll back to the past but would roll forward to the past, a contradiction in terms.