Time travel is surely possible, just not into the past.
Whoops! Davidbw1 already said that.
Silo and DavidBw1, if you’re referring to the Einstein theory, isn’t it true according to that theory, travelling forward in Time requires moving faster than the speed of light? (Which is also impossible the last time I checked.)
Also, I can’t buy into the notion that there could be unnoticed or incognito Time Travelers amongst us. SOMEBODY, would be making MONEY off it, if it were possible.
Actually, a recent issue of Popular Science (or Popular Mechanics) explained how some physicists now believe there is a way (theoretically) to travel back in time; this method also appeared in Discovery magazine a few years ago. First, create a wormhole (this is where we encounter our first problem). Second, start the wormhole spinning (at this point, they haven’t quite worked out the math, it may be that to spin a wormhole requires an infinite amount of energy). Now you can enter the wormhole and exit in the past, but only as far back as the point in time when the wormhole was originally created. Even so, it opens up some intiguing possibilities. For example, if the exit is close enough to the entrance, and your spacecraft is fast enough, you could enter the hole on the first testflight and arrrive at the entrance before you left, thus negating the need of making a testflight. Another example they presented was firing a billiard ball into the wormhole, and having it emerge in the past to strike itself before it entered, thus preventing it from entering. More work and research is required!!!