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  • Annika Santhanam

The Science Behind Time Travel

Time Travel has been, and is, a fascinating topic that has been explored through a multitude of movies like Back to the Future, Terminator, Interstellar etc., and in TV shows such as Timeless, The Flash, and Agents of Shield.


In The movie "A Sound of Thunder", a group of people travel back in time to the time of the dinosaurs, to hunt a T-Rex, and when a hunter accidentally steps on just one butterfly, the future is altered drastically. The movie explores how a minor change in the past could have a ripple effect altering the future. Another time travel movie popular amongst teens is Back to the Future, in which a teenager named Marty McFly gets accidentally thrown back into the 50’s by an experiment created by Doc Brown who owns a time-traveling DeLorean (a type of sports car). And, as almost every time travel movie depicts, Marty McFly has to make sure that his parents fall in love with each other to ensure his own existence in the future. Even in The Flash and Agents of S.H.I.E.L.D, the characters travel forward and back in time and end up changing the future. All of these scenarios push us to ask a vital question: is time travel possible?

According to Einstein’s theory of special relativity and the way wormholes work, yes.

According to the scientific and technological limitations of today, no.

Let me explain these two statements.

The Twins Paradox and Einstein’s Theory of Special Relativity

Einstein’s theory states that the faster you move through space, the slower time you experience. This leads to The Twins Paradox. This paradox states that if one twin stayed on Earth, while the other hopped in a spacecraft and traveled near the speed of light, when the traveling twin comes back to Earth, the stationary twin would have aged by a huge amount of time, possible 80 years, while the traveling twin wouldn’t have aged at all. This is essentially time travel, since the second twin was able to travel forward in time to when his other twin was very old while he himself stayed mostly the same age. The only limitation for this theory is that for the Twins Paradox to occur, one would need to travel near or at the speed of light. There are no spaceships today that could manage or travel at that kind of speed, and if it did try to travel at speeds like that, the ship and most likely the traveler would disintegrate.


Wormholes could also be used to travel forward and back in time. Wormholes are giant portals in space that are able to warp space-time. If one “mouth," or opening, of a wormhole stayed stationary while the other “mouth” moved relatively to the first, a traveler would be able to move through the bridge of the wormhole to a different point in time to which they came from. This would allow them to move forward in time. However, they wouldn’t be able to travel backwards in time any further than the time the wormhole was created. For example, if the wormhole was created in 2018, one could use the wormhole again in 2129 and go back to 2018, but couldn’t go back to 1989. Another problem with this theory is that a time travelling-capable wormhole would collapse as soon as it was created. There would be no way to enter or travel through a wormhole like that. Additionally, we do not have any technology today that would be capable of creating a wormhole in space, preventing us from using this theory to travel through time.

Time Travel Today

Believe it or not, forms of time travel have been experienced today. No, I’m not talking about that supposed time traveler from 6491. The Twins Paradox has actually been proven in real life.

The Kelly Twins

Scott Kelly and Mark Kelly are two identical twins working at NASA. Scott Kelly departed on a trip to space for 11 months, and when he came back, the genetic tests run between him and his brother to spot any differences came up with something surprising. The telomeres, which are indicators at the end of chromosomes that shorten with stress and age, of Scott Kelly were longer than Mark’s. Because Scott had been traveling at a faster speed than Mark, Scott came back to earth 13 milliseconds younger than Mark. This is an example of the Twins Paradox in action, because the travelling twin (Scott) came back younger than the stationary twin (Mark), and the travelling twin technically traveled 13 milliseconds into the future.


Plane clocks are almost always slower than clocks on land, but only by a few milliseconds or seconds, since the speed of planes isn’t that fast. The clocks on planes are traveling at a faster speed than clocks on land, leading to them experiencing slower time. This is another physical example of the Twins Paradox with time itself, because the traveling twin (the plane on the clock), experienced less time than the stationary twin (the plane on land), because the traveling twin was moving at a faster speed. Technically, the traveling clock moved a few milliseconds/seconds into the future.

The Final Statement

So is time travel into the future possible? Yes! We probably just have to wait many, many, many years for machines to be created that are able to travel at the speed of light without disintegrating in order to travel forward through time, or wait for wormhole-opening technology! Either way, time-traveling isn’t possible as of right now, but in the future, the possibilities will be endless.

Thanks for reading, and stay tuned for future Science Behind the Movies articles!


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