Is time travel really possible? I believe almost everyone at one point or another in their lifetime have thought about this question. There are instances when you wish you could go back in time to prevent something or maybe you dream to travel to the distant future to see how life would look like then.
While the idea of traveling in time is very exciting, we’re yet to see any practical evidence of such act. Not only that, but it seems like scientist almost unanimously agree that traveling to the past is probably impossible. However, as crazy as it may sound, Einstein’s math suggests that traveling to the future is actually possible. Moreover, his claim has been tested and validated over and over again by modern means.
Going Back In Time
You may have heard about the Grandfather paradox. It basically argues that if someone goes back in time and kills their own grandfather, it prevents the existence of their father or mother and therefore their own existence. Hence, they couldn’t have existed to travel in time, but they do. This paradox has solutions in quantum physics but they are within the assumptions of a multi-verse.
There have been a lot of claims and legends, videos and pictures of seemingly time travelers that went back in time. For example, here is a picture of the re-opening ceremony of the South Fork Bridge in Gold Bridge, British Columbia back in 1941. Notice the hipster guy in a printed t-shirt and sunglasses? He’s even holding something in his hands that seems to be a DSLR camera. And no, this is not photoshopped.
It turns out that those sunglasses were invented back in 1920s and his shirt is also a sewn-on emblem, the kind of clothing often worn by sports teams of the period. What he is holding is a camera but it is a Kodak Folding Pocket model.
You can see a list of alleged time travelers here on this Wiki page. I hate to break it to you, but these all have been debunked at one point.
Going Forward in Time
Albert Einstein explains his 4th dimension, the concept of time in special relativity with a famous example. Imagine a man named Jack standing in a train carriage traveling in a steady speed. Jack holds a ball and he starts bouncing it up and down. (A.) There is also Jill who stands in the platform watching the train pass through. What would be she seeing by looking at Jack? Between the time Jack drops the ball and catches it again, Jill would see the ball moving slightly down the track because the train is moving forward. (B.)
This means that Jill sees the ball travel longer than Jack does in the same time period. Because speed = distance / time, Jill actually sees the ball move faster. For the same speed, we have a different distance and the only way the equation would balance is by taking a different rate for the time factor.
Thus time must take different rates for people moving relative to each other. This idea may sound crazy but it has been tested and validated back in 1970s. Scientists boarded a jet plane with a super accurate atomic clocks that were synchronized with some others left on the ground. After the plane had flown around the world, the clocks onboard showed a different time from those left behind! This is the theory of time dilation, which is a difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from a gravitational masses.
You may ask, what does this has to do with time travel?
At the speed of trains and planes, the time difference is not a lot meaning that you would need an atomic clock to record it. However, if you travel faster you would start to notice the time dilation add up. In fact, if you could travel close to the speed of light around our galaxy and come back, what could seem a year to you, would be close to a thousand years passed on Earth.
Yes, you can travel to the future … technically.
Although all of this is theoretically possible, we are far from actualization of such technology. We had to build the LHC with 27km in circumference just to accelerate the subatomic particles close to the speed of light. Moving large masses like human body or spaceships in such speed requires enormous amount of energy. Who knows, maybe one day when we finally became a Type III civilization (measured in Kardashev scale) this would be a reality.
In the end, for the sake of trivia or to feed the curiosity of one’s mind, you can watch Matthew Santoro’s entertainment video on “10 Pieces of Evidence Time Travel May Exist!”. Again, these have no scientific basis and they have mainly been disproved.
Originally published at medium.com on November 23, 2016.