Who among us hasn’t seriously considered that time travel could become a real possibility some day? I know I have. Alas, most common folk (and quite a few scientists) think of such a thing as being better left in the realm of science fiction , but does that really mean that there’s no chance at all of ever making it happen? After all, weren’t most of the amazing technologies available today considered impossible at some point? Go back just one hundred years (in your mind, for now) and you will find that computers, smartphones, drones, space flights, the Internet and a myriad of other things would have seemed highly unlikely to the people of that time.
So, why do most dismiss the possibility of time travel when mankind has proven over and over again that we can take the seemingly impossible and transform it into reality? It’s true that sometimes it just takes a while and it’s definitely also true that we’ve been waiting for this to happen for quite a bit without any real results. One of the most common arguments that attempt to refute the possibility of time travel states that if we do invent a time machine at some point, then surely someone from the future would travel back and tell us all about it. This argument seems similar to the notion that “if aliens really exist they would have visited us by now” in the sense that it assumes that aliens indeed can (and more importantly, want to) visit us.
The same goes for potential time travelers. If possible, would someone really attempt to time travel back from the future just so skeptics from our present can have proof that such a thing will actually be real someday? Probably not. Just like people from the western world don’t go around jungles looking for lost tribes in order to show them the wonders of the smartphone, potential time travelers from the future are pretty unlikely to want to visit a less advanced society and reveal to them the secrets of time travel. But let’s set aside the speculations of a layman for a moment and take a look at what science has to say about all of this. Surely, if anyone can tell us if time travel is indeed possible then it’s the scientists who have spent all their lives trying to give answers to some of the most biggest mysteries of the universe.
Surprising or not, a number of theoretical physicists actually do believe that time travel is possible and they’re not making that claim based on just gut feeling or wishful thinking. These scientists are looking at the works of Albert Einstein and other great physicists for answers and that’s definitely a great place to start. According to Hermann Minkowski, time and space are not separate but actually intimately linked together and form the fabric of spacetime (or timespace). What’s more, Albert Einstein took the idea further and proposed that spacetime is very much not a flat fabric, but rather something that can bend, twist, and even fold on itself. In theory, finding a way to manipulate spacetime could lead to a great number of extraordinary possibilities, such as faster-than-light travel, teleportation, and even time travel. Needless to say, we’re not yet at the point where manipulating spacetime is feasible, but perhaps one day we will be, which is why we should keep an open mind in regards to these extraordinary possibilities, just in case.
In fact, there’s a certain scientist out there who not only sees time travel as a real possibility, but is even dead set on creating an actual time machine some day soon. Ron Mallett is a theoretical physicist who seems pulled straight from H.G. Wells’ The Time Machine novel as he’s attempting to put together and use the machine in order to contact his father who passed away when he was only 10. Mallett has been working on this project for a very long time and even came up with a prototype which uses carefully arranged lasers that swirl the fabric of spacetime inside the machine into a vortex. The main idea here is that light (from the lasers) can twist space, and therefore time seeing as how the two are linked together . Mallett’s first order of business is to send information to the past via a stream of particles that act like binary code, which can be interpreted by the receiver. Although I’ve mentioned that people are unlikely to physical travel through time in order to meet someone from the past, Mallett is only trying to send information for now.
As you might imagine, if Mallett succeeds his actions will create a paradox since his father’s death is the primary reason for why he started researching time travel in the first place. Paradoxes are yet another reason for why time travel seems like science fiction and is easily dismissed as a real possibility by most people. However, there is a work around to this and it involves parallel universes and alternate timelines. Specifically, some theoreticians speculate that if you could indeed manage to time travel you would not be part of the same universe you left from, but rather create an entirely different one upon your arrival.
Moving past the already well-known grandfather paradox, let’s say you went back in time and killed Hitler, which seems to be something that many people from the present desire for some reason. Don’t get me wrong, Hitler was bad, but killing him would change pretty much everything we know and not necessarily for the better. In any case, some physicists speculate that you can not kill the Hitler we know about since the events that he participated in have already unfolded and can not be changed. Rather, if you were to travel into the past – let’s say before the Nazis rose to power- you would be creating a brand new timeline and killing Hitler would not have any effect on this timeline. It would be interesting to see how the world would be like if you managed to pull that off, but ultimately what’s done is done in your timeline and all the events you know about can not be changed.
This theory may sound a bit far fetched, however, it does seem to make more sense than the idea that a person could time travel and change events that have already occurred in their timeline. Changing anything – no matter how small – in the past is believed to have long-lasting consequences on things to come, but what about changing the future? Here things get even more interesting because anything you might be able to change is apparently supposed to happen, so in a sense you can’t actually change anything. This is because of the connection between time and space, which we discussed earlier. Theoretical physicists like Brian Greene suggest that the universe doesn’t have a distinction between past, present, and future, so again, everything that’s supposed to happen in the future has actually happened already. Sounds strange? That might be because we tend to view time as a one-way train that always goes from point A (past) to point B (future) and never the other way around. However, physicists propose that although we humans are only able to move from A to B, there’s little to prevent time itself from speeding up or going the other way around.
Case in point, black holes. A black hole forms when a massive star dies and collapses on itself leaving behind only its gravity to tell the tale. At this stage all the former star’s gravity and mass have essentially been crushed and concentrated into a very small area. This results in a ‘gravity gone wild’ type of effect where the gravity is so strong that it pulls within everything that crosses its path, including light. What’s more, a black hole also distorts the fabric of spacetime. Whereas down here on Earth Ron Mallett is using light in an attempt to twist space and time, out there black holes are already doing it but on a much larger scale. The problem is of course that we are not able to use black holes as a means of time travel, nor would that be an effective way to do it even if we could. Having said that, there might be a better way of achieving the seemingly impossible feat of travelling through time, but it involves punching a hole through spacetime and creating a wormhole.
While black holes occur naturally throughout the universe, a wormhole would have to be created artificially by an advanced civilization. Wormholes are hypothetical tunnels (sometimes called bridges) that could allow somebody to travel from one point of spacetime to another one in just a matter of moments. A wormhole may sound like something invented by science fiction writers, but the idea was actually based on the work of Albert Einstein and Nathan Rosen. Wormholes are sometimes also referred to as Einstein-Rosen bridges after the two great physicists. A lot of people tend to think of wormholes as the perfect tool for traversing great distances of space that would otherwise be impossible to cross using conventional means, but they’re so much more. These bridges could also allow for time travel and even for travelling to a parallel universe. Needles to say, creating a wormhole and some type of vehicle that can pass through it and survive the journey would require technology and sources of energy that we currently don’t posses or maybe don’t even know about yet. A pretty good depiction and explanation for how wormholes work can be seen in the movie Interstellar (see the short clip below).
So to sum things up a bit, time travel could be achieved in multiple ways as you can see, but three of the preferred methods would be either a time machine that uses light to bend spacetime, a black hole that uses gravity to do the same but in a much more meaningful way, or a wormhole that acts like a bridge between two separate points in spacetime. Unfortunately, there are several problems with each of these methods depending on where you want to travel to. The wormhole seems like a pretty sound of option for travelling to the future, but not so much for travelling to the past since according to the same Albert Einstein (or rather, his general theory of relativity) you would not be able to travel to a point before the wormhole was created. As for a black hole, we’re talking about something that eats stars for breakfast, so getting near it would probably be the most dangerous thing a person can do. As a side note, a hypothetical spaceship would not actually have to go inside the black hole, but would have to get uncomfortably close to it in order to make use of the spacetime distortion it creates. Lastly, the time machine prototype that uses lasers might end up working, but it seems like you would only be able to send information and the receiver would have to know how to decipher it, which sounds like a difficult task in an of itself.
Aside from all of these, another popular means of time travel involves FTL travel (faster than light). I wanted to mention this last because it seems the most interesting, at least to me. General relativity suggests that an object travelling near the speed of light will experience time slower and if we take the idea further it would mean that travelling faster than light would theoretically allow the object to also travel backwards in time. The problem with this is that the speed of light is considered to be the “universal speed limit” and can not be surpassed. However, this is believed to only apply to objects travelling within normal spacetime and there are concepts that attempt to circumvent the problem by bending spacetime as they move instead of trying to accelerate to the speed of light or surpass it. The Alcubierre drive is such a concept, although most have come to know it as a warp drive thanks to popular movies like Star Trek. There’s plenty of controversy surrounding the idea of a warp drive given that, among other things, the energy requirements seem to be impossible to achieve. That’s not to say that we should lose all hope though, because it’s very likely that we will find sources of energy that we don’t know about yet.
Bottom line is that time travel could become a reality for future generations, but for those of us living in the present it seems extremely unlikely to achieve with our current technology. Some day we might take such a thing for granted just like we tend to do with global communications today, but for now all we can do is continue to create books and movies that speak of more advanced civilizations with the power to manipulate space and time. Today we can only dream about becoming time travelers, but that’s actually a very important first step that we must not dismiss because hopefully people like William Arthur Ward are right when saying that “If you can imagine it, you can create it. If you can dream it, you can become it.”