By James Zheng, Blogger and Amateur Physicist

I know it’s kinda unusual to see a title like this, especially from an anime reviewer. As I was considering what anime is worthy of recommending, I came up with this interesting topic to share with you guys. Also, to interpret this topic in the best way there will be some physics stuff and technical terms, but I will not make this subject sound really complicated or ridiculous. What I will do is express everything in a simple way.

As the most intelligent beings on the Earth, humans have infinite ambition in the realm of science. An example of this is the invention of new gadgets. And one of the most controversial, or even most impractical ideas, is time travel. Describing time travel is just as difficult as unravelling a thousand threads twisted together since we don’t really have a solid concept of it, fundamentally. It’s a process of travelling to the past or future, which sounds absurd, right? So, this wonderful scientific idea contradicts with the Theory of Relativity (a basic theory about space and gravitation which also introduces all the special phenomenon in physics) and even disobeys the principle of nature (the most basic principle that applies to the whole universe about how things change).

Here is one of the biggest concerns, the temporal paradox, also known as Fermi’s Paradox. It could entirely negate time travel while also telling how time travel could lead to a false interaction between cause and effect. Simply put, there are many examples to explain what a temporal paradox is. Let me give a common example: let me assume that person A went back to his past, then person A killed his father (person B) before B got married, and the existence of person A turns out to be an unknown being since if person A killed his unmarried father (person B), person A would not have been born. The logic of this example is really clear; the cause is that person A killed B and therefore cannot be borne of B. In this application of temporal paradox, when we travel to the past, we can’t interfere with the reality in the past, similar to the principle of nature that humans cannot change something which already happened in the past; otherwise, it would create complete chaos.

However, as I mentioned earlier, mankind has limitless ambition. And, we would all agree that temporal paradox sounds absolutely reasonable and unattainable; actually the realm of science ignores one possibility, an assumption called parallel universe. At this time, let’s go back to that same example to explicate parallel universe. What would happen if A kills his unmarried father B this time? There will be two universes, or paths split from A’s life. One path is the history that B died, but another one is the original history that A can never change, and which means the truth that B died still remains but actually A will go to the path that B died and stay in that path. Moreover, parallel universe is not the only factor that could possibly debunk temporal paradox; there are plenty of other circumstances that could affect it.

Now let’s see how could we disobey the Theory of Relativity and principle of nature in a “correct” way. At first, you might see a few articles which claim if humans discover a speed faster than light, time travel will be plausible. But, all the evidence and reasons that they have given so far are just abstract. I am not criticizing them. Scientists often use sophisticated words and concepts that people cannot understand, which they normally would see as something impressive, so the majority of people just don’t get it. And, in my opinion, to produce a special phenomenon called a wormhole (like a tunnel that links two alternative timelines) and look for a high gravitational field will possibly accomplish time travel. Secondly, before I tell you how a wormhole works, I am going to explain it. A wormhole is a passage that connects two universes, which also refers to two time points so that it allows a person to travel through time, certainly a one-way trip (by the way, I write some extra crazy information about wormholes at the end of this article;, check it out if you want to). At some point, wormholes will definitely be a breakthrough if scientists find proof to validate them… wait… haven’t they proven it already? Although it’s only a hypothesis, it’s indeed a scientific theory that some well-known physicists such as Ludwig Flamm and Nathan Rosen were trying to prove.

How about high gravitational field then? First, there is one thing you need to know. On any planet, when gravity is elevated extremely high or low, the time is either slowing down or speeding up. Same as on earth, our standard comprehension about time is determined by gravity. As a result, time is vulnerable, by which I mean it has many flaws, perhaps when you go to a planet that is far away from the Earth, there will be a gigantic discrepancy of time between that planet and Earth. The discrepancy will depend on how different the gravity is as well so that decides how fast time moves.

Finally, I hope you liked this article written by an amateur who is truly interested in physics. All of the above views are absolutely my personal and subjective researched views. I do not mean to make this topic contentious, but please leave your comments or questions, or correct some places that you think I am wrong. I will happily respond.  

Note: Here is the crazy information of wormholes. Theoretically, wormholes are space tunnels connecting two distant timelines, just like the whirlpools in the ocean, which are everywhere but short-lasting. These temporal and spatial vortices are caused by the rotation of the stars and the attraction of gravity. Just as a whirlpool can make the water surface closer to the bottom, it can make two local spaces which are far away from each other very close instantaneously. But some people assume that a certain dark matter can keep the wormhole open because some of them contain positive energy and negative mass at the same time; it can create a repelling effect to prevent wormhole closure.

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Editor: AJ Patencio