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To travel INTO the future is comparatively easy vs going back in time. All one needs to do to travel ahead is gather enough energy to accelerate themselves to great speeds. The faster you go, the more you will have moved ahead in time when you ultimately come to a stop. This actually happens all the time, every time you're using some means of transportation, most noticeable (although in mere fractions of a second) is when you travel in an airplane.

Here's an explanation of time dilation that I wrote myself a few years ago. Hope it makes sense. The graphic I found on the Web.

First, from Wikipedia: "One second is defined as 'the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom'..."
http://en.wikipedia.org/wiki/Second

Now imagine, instead of a vibrating 'caesium 133 atom', we have a beam of light bouncing back and forth between two mirrors within a vertical tube. Now let's say, for the sake of argument, that it takes precisely 'one second' for the light beam to reach the top mirror (tick), reflect off it, reverse and reach the bottom mirror (tock).

Now let's say the light tube, or 'light clock', is resting on a flatbed train car, and on the flatbed is an observer who we will call "Observer A". To Observer A, who is moving along with the train and is therefore 'at rest' with respect to it, the light beam simply travels from the bottom of the tube *vertically* to the top of the tube and then straight back down again. From the relationship, speed equals distance over time, we get time equals distance over speed. So this is then how Observer A defines time (t=distance/speed). Important to note here, is, according to theory and supported by experimental evidence, light travels at the SAME SPEED for ALL observers.

Now let's say there is an observer B standing on the embankment alongside the train watching it pass by. From this observer's point of view, or frame of reference, the light beam does not simply travel vertically up and down but rather in a slanted or diagonal path, since the train is in motion, let's say from left to right as Observer B sees it. Now since the light beam travels a diagonal path between tick and tock, again, from OB's stationary point of view, the light beam therefore is traveling a LONGER distance (from OB's perspective). Therefore, since the light beam is traveling a longer distance (from OB's perspective) AND since light travels at the same speed for all observers, the light beam MUST take a longer time to bounce between the two mirrors (tick-tock). Therefore, the two observers (A and B) do NOT agree on what a "second" is.

http://galileo.phys.virginia.edu/classes/252/srelwhat.html

The mathematical relationship between the two paths is based on the Pythagorean Theorem for right-triangles that many of us used in high school.

-ETL

Here is that mathematical relationship (between time as perceived by the two different observers) that is derived from the familiar Pythagorean Theorem (a squared + b squared = c squared, c being the longest leg of the 90 degree (right) triangle depicted in the above illustration):

$\Delta t' = \frac{\Delta t}{\sqrt{1-\frac{v^2}{c^2}}}$

the faster one goes, the slower time moves while a fixed observer will have normal time. Not really time travel in the since a person jumps from a moment of present time to the past or future.

And it takes a lot of energy to accelerate toward the speed of light, which is theoretically impossible in “normal” space.