This may not be that new a question, but it's something I don't know. I undrstand the good Doctor is the last of his kind. The Time Lords all perished in the Time War. My question is if they're time travelers, why can't he go back to before they were all killed, or why hasn't he encountered any other time traveling Time Lords?
I'm sure there's probably an answer to this, but I'm not sure what it is. Thanks.