Time travel is a theme that appears frequently in science and science fiction films. Most of us can give an example of a DeLorean or a TARDIS in the blink of an eye. It is, however, a fiction which can make you wonder – can time travel come true?
Time travel from the point of view of physics
For years, scientists have been considering whether time travel is possible – the paradoxes behind this theory keep many researchers awake at night. From the point of view of quantum physics, which lies on the verge of academic research and science fiction, time travel is possible – but classical physicists are a bit more skeptical. The well-known Albert Einstein made a huge contribution to the development of quantum theory – it was he who first noticed the options that would allow the possibility of time travel.
Einstein’s observations of traveling in time were completed by Kurt Gödel, who in 1949 showed that Einstein’s equations allow the possibility of a universe in which you can travel backwards, into the past. In physics, this is known as closed time loops. Since then, interest in the subject has increased and possible scenarios for such journeys have been constructed. Is time travel possible?
Theoretically, time travel is feasible, but it requires the creation of extreme conditions, even impossible to implement, such as, for example, traveling faster than – or at least close to – the speed of light, or constructing the so-called wormholes. Moreover, past journeys could lead to the so-called causal anomalies that cause various paradoxes.
However, how does this relate to tangible evidence, such as the novel by the American writer Morgan Robertson Futility, which in 1898 described the unsinkable ship “Titan”, built in Great Britain, which went to the bottom as a result of a collision with an iceberg, while on board it was not there were enough lifeboats. Somehow, fourteen years before the Titanic disaster, he reported exactly what happened.
The Grandpa Paradox – A Simple Example of Why Time Travel Is Impossible
You may already have heard of the famous grandfather paradox that was supposed to prove that time travel is not possible. Imagine going back in time and killing your grandfather before he even fathered your father. But if it does, how is it possible that you exist at all? On the other hand, if you don’t exist, who then killed Grandpa? This is how the paradox arises.
This issue appears in many films and works of literature. For example, think about Back to the Future, in which Marty goes back to 1955 and interrupts his parents’ courtship, which keeps him from being born. Well, since he was not born, he could not disturb his parents, and since he could not disturb his parents, he must not fail to come into the world – a completely vicious circle. Although many films treat time travel neglectfully, ignoring paradoxes and logical turmoil.
When citing time travel theories, it should also be emphasized that there are physicists who say they have found evidence of time travel without paradoxes. On the basis of mathematical calculations, they concluded that logically, changes in the past cannot have an impact on the future, because otherwise the journey would not have to take place at all. Consequently, if we knew how to do this, we could easily go back to a world from thousands of years ago.
There is another time travel paradox – the twin paradox – which indicates that speeding up time is possible. Importantly, there are people who have personally experienced this phenomenon. According to Einstein’s theory of special relativity, there is such a thing as time dilation – the passage of time is related to the speed of movement of a given object. This means that the faster an object moves, the more its time slows down in relation to other objects that are moving slower or remain stationary.
Wormholes and white holes
While time travel through wormholes is theoretically possible, this does not mean that the theories make any sense. A wormhole is a kind of bridge between at least two regions of the universe. Their existence has not been proven so far, although Einstein’s theory of relativity allows for the presence of tunnels in some space-time models. However, the calculations so far also show that, even if wormholes do exist, they are too unstable to send anything through them.
When traveling in time, it is also worth mentioning the theory of the white hole, which seems to be a consequence of the existence of a black hole. Scientifically speaking, a white hole is the opposite of a black hole – a black hole sucks in matter and a white hole gives it back. White holes play a vital role in the way we perceive space-time – objects inside can get out and interact with the outside world, but no external event will ever have an impact on the inside because nothing can get in.
This theory seems incredibly complex, and you might be wondering what it is like in the end – is time travel possible? Numerous hypotheses and studies show that, although the topic is still shrouded in mystery, and its thorough understanding would require a better comprehension of the theory of gravity, and at this point you should treat this topic as a mathematical curiosity, and not as a proven theory. To make it more interesting, Antoine Suarez, who in 2002 proved that time simply does not exist, contributed to the reflection on the theme of time.
The experiment carried out by Suarez is quite simple: he illuminated the crystal with a laser, obtaining beams of photon pairs, which he led separately through a fiber-optic cable to two translucent mirrors. Chance was to decide whether a single photon would pass through them or be reflected. As it turns out, the two photons that were created simultaneously in the laboratory remained connected – either both were reflected or both passed through the mirror. Whatever was happening to them, it was happening absolutely simultaneously. This is where the problem arises – even though the mirrors can be many kilometers apart.
Time travel in books and movies
Time travel is a theme willingly used in both novels and movies. The movie Back to the Future and a well known film Interstellar are two examples in which both paradoxes and a time loop theme appear – the plot is based on the discovery of scientists who have identified a wormhole enabling the search for a new home. The film is based on a scientific theory developed by Kip Thorne – a physicist at Caltech.
Time travel is also a treat for the creators of the series Lost in time, where the main character, Sam, together with a group of scientists, constructs a vehicle that takes him to the past. An interesting aspect of the series is the fact that Sam does not travel in time physically, but only his consciousness goes to the bodies of random people from previous eras. This is not the only series. Time travel also appears in Doctor Who about the adventures of a Time Lord.
Time travel also appears in literature. A book that focuses on this topic is a well-known work – Time Machine by H.G. Wells. In it, you can follow the fate of a Time Traveler who, using the vehicle he has created, moves hundreds of thousands of years into the future. He observes a civilization that gradually collapses, approaching the intellectual level of the first humans, and the Sun slowly enters the last phase of its life.
There is still no clear answer to the question whether time travel is possible, at the moment we only have hypotheses. Regardless of the lack of scientific evidence, time travel is undoubtedly a strong theme that ignites the imagination of the creators.