Is Time Travel Possible?


       We all dream of time travel. Being able to go back in time and change or redo anything that we desire has always fascinated people for centuries. The topic of time travel has become really popular, as it is being portrayed in numerous TV shows, such as Doctor Who; countless books, such as The Time Machine; and many movies, such as Looper. With our growing understanding of the sciences and our latest technological breakthroughs, more and more people are becoming less skeptical of the possibility of discovering time travel in the future. This has become such a prevalent topic that companies like NASA have begun studying it. Though a lot of people claim time travel is achievable, other skeptics doubt it, so it must be questioned: is time travel possible?


What is Time Travel

       What is time travel? Time travel is the ability to go from the present time to a different time period. That is, escaping from the current time period and entering a new one. This question is really hard to answer as it depends on what sense of time travel you are discussing; most people assume that when time travel is mentioned, the person is referring to traveling back in time. Most people neglect the prospect of being able to travel to the future. Each must be talked about separately and cannot be grouped up together. The logistics behind each is extremely different, and there are different possibilities in each case.


A time machine portrayed in the movie Back to the Future. This machine or anything similar to it doesn’t exist right now.



Traveling to the Future

       Time traveling to the future involves one traveling to a point in the future that exists. If you are thinking of the traditional sense in which you enter some sort of machine and click a button to travel 10 years in the future, then no, it’s impossible. This technology of spontaneous transportation has not been discovered. We have not discovered anything that will simply transport something to the future instantly, but future breakthroughs might. Though this type of space travel does not yet exist, a different way of traveling forward is known. This new way is possible due to the work of Albert Einstein.


German theoretical physicist Albert Einstein, circa 1947



       The theory of special relativity was discovered by Einstein. This theory is crucial to understanding how time works. The theory states that time is not linear and is not the same for everyone. The perception of time from the perspective of two different objects that are at different speeds is different. This is a phenomenon that is called time dilation. Time slows down the faster you move. This is true while you are running; for example, when you are running, you move more quickly relative to an observer. Therefore, time moves slower from your point of view, though this change is so miniscule it is immeasurable. The highest recorded time dilation of a human is by an astronaut in the ISS (International Space Station). He stayed in orbit for around 940 days. He was moving at speeds of around 27000 km/h on the space station, therefor time dilated compared to us by 0.05 seconds. This theory has been tested as synchronized clocks were set up; one on earth and one on the ISS. After they were brought together, the one on the ISS showed that less time had passed. You may be wondering how this is helpful, but this can help us “travel to the future”.


The ISS experiences time dilation


       The theory of special relativity has dramatic and noticeable effects when we travel near the speed of light. If you were to go on a rocket that travels at 99.999% the speed of light and travel for just one day at that speed, you would come back to earth to find that everyone has aged by around 224 days. This is astonishing, as this can be used to travel to the future. Just a few weeks on a ship moving at 99.999% the speed of light can take you years into the future. Unfortunately, a vessel capable at traveling at these speeds is unheard of, and so is the technology to develop such a method of transportation. This is likely to be developed in the far future.


An example of special relativity. A rocket traveling at light speed takes one twin. When she comes back, her sister has aged more than her.


Traveling to the Past

       What if you want to see some dinosaurs? Is traveling to the past possible? Well, that’s also a no. So far, nothing exists that can allow us travel into the past. No machine that can take you there in a matter of seconds, just like on tv, exists; however, it still may be possible. Theoretically, if certain motions exist in space-time, it will be possible for us to go back in time. “Specific types of z motion in space might allow time travel into the past and future if these geometries and motions were possible” said one scientist when asked about time travel. However, this is a big IF. There would need to be a CTC (closed time like curve) for us to be able to travel in the past. If this exists, that means that we might be able to send an object back to its past, yet this is still not proven to even exist. Even if these do exist, time travel to the past might not be possible do to if we consider the principle of causality.


Example of a CTC


       Imagine going back in time and accidentally killing yourself. This would cause you to disappear in the future, thus your past self is never killed. But if your past self isn’t killed, you reappear and kill your past self. The cycle would keep repeating. This would, in turn, cause a time paradox, which many scientists believe cannot exist. So therefore if the theory of causality is true, time travel to the past can’t exist, but if causality theory isn’t right, we may be able to travel to the past.


       Another form of time travel to the past would be through the use of wormholes. Wormholes are linked openings, as in the previous picture, in the so-called space-time fabric; the pathway between them may be able to take you to the future. Going through one would bring you to a different time. The creation of these wormholes is complicated, however. A wormhole would have two entrances; one would be on earth and the other accelerating at the speed of light for a period of time. Say if the one on earth aged 12 years, and the one accelerated only 3 due to special relativity, and were both brought back to earth. If you went through an accelerated portal, you would arrive 9 years in the past! A simple example of this is folded paper with a pencil through it. The pencil would represent the wormhole. Though this is exciting new, wormholes are a long way from being fully discovered.


Simplified wormhole example


       Time travel is an interesting subject that we all love. This subject fascinates us every day. Should time travel be discovered, it would be the greatest breakthrough in human advancement, ever. Though time travel may be a long away from us,that hasn’t stopped us from dreaming!

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