How can i get back to the 8o's?

Thus far, time travel has not been invented. If time is linear, then time travel would not be possible. If past, present and future are parrallel, then some scientist must decide how to reach from one to another without causing another big bang or something similar. In short, no way is known at this point how one can time travel.

There is one exception, however; if a space craft leaves Earth and is gone for say, five light years, when it returns to Earth, the people on the ship will be couple years younger than when they left, while the people on Earth will be the same age, thus making the travelers younger than the Earthlings.