A silly point, but one that always pops up when someone says time travel is impossible.
Not only is time travel possible, but we all do it all the time. Literally.
Every one of us is traveling forward through time, into the future, at a uniform rate of 60 seconds per minute. See that thing on your wall with the numbers on it (or your wrist, or the corner of this screen)? That machine is a device that measures our progress as we travel through time.
[Note: this weird thought reminds me of another post last year–that one was loopy, too.]
Gently Hew Stone 