By now you've probably seen the video of filmmaker George Clark dissecting a piece of footage from a Charlie Chaplain movie, in which it looks like a woman is talking on a cell phone . . . in 1928. Although there are many possible explanations which range from amplifying her hearing to adjusting her hat, curious folks are left wondering: is time travel really possible?

According to my favorite time travel flick of all, Back to the Future, of course! But in the real world, time travel could move from fictional films to real life with the right tools. Check out a clip from the Back to the Future 25th Anniversary trilogy extra, "The Physics of Time Travel," as Physicist Dr. Michio Kaku breaks down the truth behind moving forward and backward in time when you read more.