Time Travel
In a classic Star Trek episode, “The Naked Time”, the Enterprise is thrown back in time about 71 hours. Is time travel really possible? The answer is ‘yes’. Many experiments have all ready been performed verifying its validity.
Suppose you and your friend just happen to have two highly accurate atomic clocks. One is with you in San Francisco and the other is with your friend in New York. Just before taking off from the airport in route back to New York you sneak a call to your friend and synchronize your clocks. When the jet lands in New York, your friend greets you at the airport. After exchanging your hugs and hellos you check the atomic clocks to see if they’re still synchronized. To your amazement your clock is twenty-two nanoseconds behind your friend’s, just as Einstein would have predicted! Similar experiments have been performed using the fastest jets available traveling non stop around the world. Two atomic clocks were synchronized, one placed on the jet the other left at the airport. After the jet circled the world and landed, the two clocks where compared and the times differed exactly by the amount predicted by theory.
The speeds that star ships would have to travel at are many times greater then that of a jet on Earth. Therefore the time dilation effects would be much greater. How much time difference would there be for someone traveling to the nearest star and back? This is a well known example called “The Twin Paradox”. In this situation two twins Anton (twin A) stays at home on Earth, while Bertram (twin B) cruises about the universe at nearly the speed of light. Since Bertram’s rapid speed has slowed down his clocks and biological processes he returns home to find himself much younger then Anton. But from Bertram’s point of view he was stationary and Anton was traveling at nearly the speed of light. In this case shouldn’t Anton be younger? What’s going on here?
Up until now we have only considered inertial reference frames (reference frames at constant speed). In the case of the twin paradox acceleration is involved. One of the two twins must undergo acceleration to match the other’s reference frame. Therefore this problem has to be looked at from the point of view of the person who’s reference frame remains unchanged. For the twin paradox it is Anton’s reference frame that remains unchanged hence Bertram’s clock tics more slowly.
In conclusion time travel is possible due to legitimate time dilation effects. The rate of change of time for one person can be different then for another person. For instance, we all experience time elapsing at the rate of one hour per hour. In the twin paradox both Anton and Bertram also experienced time ticking off at a rate of one hour per hour. However, Anton measured Bertram’s clock (assuming he could see it) at a rate of less then one hour per hour. As a consequence Bertram wound up traveling into the future. But can he get back?