We can’t time travel backwards but only forwards. I think by thinking of a past you were in or shared with someone, I think it is like time traveling, but we can’t go back in time. We can only go ahead because sometimes time is our friend or our enemy. It all depends on how you want to view it and no one else. It’s a tricky subject, because your mind thinks of the past while it’s playing in your mind. It’s actually happening while it already happened. Math is mostly included in time traveling back to the past, but it is impossible to do so.