I suppose it requires a stretch of the understanding of what it would mean to go "back in time". If you were to literally travel backwards in time, but not reta

I suppose it requires a stretch of the understanding of what it would mean to go "back in time". If you were to literally travel backwards in time, but not retain knowledge of the future, that would be useless. What is desired is to be in a state where you are at time T with knowledge from time T+1. So, by traveling through the wormhole, you would arrive there with knowledge that could not have reached it from the direct path until some time later. You might even travel through the wormhole, observe your own past, and return back again. But yes, generally speaking, there is no known means to travel back in time before the moment of creation of the time machine itself.