Hello, TimeEmperor here! There are not many shows or movies that contain time travel to the past. But one of these shows is an anime called Steins;Gate, which I love. For those who never watched the anime I’ll briefly tell it’s plot. The main protagonist Okabe is a scientist and with his friend Daru he accidentally created a time machine of a microwave (that part is really weird). He then proceeds to mess with time and he gets his friend killed and he has to undo everything that he did to save her, but that would also kill his love. I tried as hard as I could not to spoil the series, because if you haven’t seen it, you should, it’s a great series. But the science of it is flawed.
The series bases itself on the real life event involving John Titor and the many worlds interpretation. Let’s start with the latter, because Titor used it to explain himself. Now in physics there are two main branches of physics, which explain different thing. The first one is classical mechanics, which you learn mostly in school; it’s about the big objects, like you, rats and planets. The second one is called quantum mechanics, and in school you barely talk about or not talk about it at all. Quantum mechanics explains how the smallest of things – electrons, protons, photons and so on – interact with each other. The MWI stems from this branch.
Quantum mechanics are different from classical mechanics not just because of the scales of measure, but also of how things interact. For instance, if you roll a ball, you can clearly measure where the ball is and how fast he is moving. But in quantum mechanics that is not the case. If you roll an electron you can accurately know either it’s position or it’s speed, but never both, which is counter intuitive. This principle is known as Heisenberg’s uncertainty principle, which is not named after the famous king pin of meth, but rather after a mathematician. But don’t worry we are not going to talk about that principle in depth, we just need some concepts of quantum mechanics.
Before we talk about MWI we need to talk about a famous thought experiment in quantum mechanics – Shrodinger’s cat. But before that I must explain something rather weird. In quantum mechanics there is something called spin which is an intrinsic property of angular momentum carried by a particle, but more roughly speaking it’s how the particle spins around it’s own axis. Let’s say that a particle can spin either clockwise or counter-clockwise. Quantum mechanics tells us that if we look at it one way it will spin clockwise, if we look in another way, it will spin counter-clockwise, and if we are not looking it spins in both directions. This is called the quantum superposition. Roughly speaking it says that a non-observed particle is in all it’s states at the same time. Here is an analogy for better understanding: if you look at a girl one way, she puts on a red dress, if you look in another, she puts on a blue dress, if you’re not looking at her completely, she is wearing both dresses. Sounds ridiculous, I know, but who was never shocked by QM never really understood it. Now, let’s continue. If a particle is observed, it’s superposition collapses, it now has to “choose” between all of it’s choices.
Now, Erwin Schrodinger didn’t think that an observer could do anything to the superposition collapse, so he created a though experiment. Let’s say we have a box, in it we have a glass bottle of poisonous gas, a hammer over the bottle, a Geiger meter which is connected to the hammer(it drops it to smash the bottle if any radioactive decay is measured) , and radioactive plutonium atoms, which have 50% chance of decaying in the next hour, and a cat. We now close the box for an hour. After that hour, before looking, we don’t know if the plutonium atoms decayed or not, so their decay is in a superposition, so they decayed and did not decay, so the Geiger meter reacted to the decay and didn’t react to it, the hammer was dropped on the bottle and wasn’t dropped, the poisonous gas was let out and wasn’t, the cat is dead and alive. But the cat cannot be at the same time dead and alive. So the cat must’ve died at some point or never died. But of course this problem is resolved that an “observer” can be anything, from an air molecule, to a photon. So the cat’s chances of survival are just 50%.
Now we can talk about MWI. Imagine that before we open the box we think about what are our odds of seeing the cat being alive? It’s simple, it’s 50% you yell out. Okay, great, but why does the function collapse towards either the cat being dead or being alive? What says that it should be that way and not the other? And to answer this question we use MWI. It says, that any collapse of a superposition is actually not collapsing, but instead creates two different time lines or world lines where both things happen. For instance of the cat experiment, the function does not collapse, instead two different world lines are created where in one the cat is alive, and in the other the cat is dead. And this goes for everything you do. For instance you can’t decide between eating cereal and an omelet. No worries, two different world lines are created and in one of them you are eating cereal and in the other – omelet.
Now we can talk about John Titor. John Titor, back in the early 2000s was a major celebrity, because he said that he was a time traveler from the future, and he talked about future events, like war of the Americas and other things, I’m not going to go in depth about his prophecies, you can find the all over the internet. What I am going to talk about is his one statement. When asked why are the things that he said were supposed to happen, but never happened, he said that it is because of the divergence of the time lines, but he said that those things are going to truly happen, but in later times. But he never specified when. Now here is the problem. Yes, he was right about the time lines in some sense. He stated the exact percentage of the divergence of the time lines, which is impossible to know, because according to MWI, you can never now on which time line you are or were, so determining that sort of thing to my knowledge is impossible. But he was right that the time lines diverge, but he was wrong about one thing. Events. You see, according to chaos theory, if you make a small change in a system, you can have drastic results. So John Titor supposedly changed the past, but it was a small change, but it had drastic changes which changed the course of history, meaning that his described events can’t have that accuracy of truly happening. So John Titor is wrong. In a sense.
So because the basis of John Titor is wrong, Steins;Gate is a somewhat wrong series, but it goes beyond John Titor. In the series, whenever Okabe changed the past, he would also transport to the other time line, while he changed the past without him being in the past from the future, he wasn’t physically in the past. So, when he sent a message in to the past, he changed the past by making two time lines in which one of the he never received the message, but he sent it, and the other one where he received the message without sending it. Because of that, he cannot transport himself or his memories to the other time lines, without physically traveling in to the past. And with this we can say, that the whole plot of Steins;Gate is wrong.
I know, this is complicated, and time travel is complicated stuff, but if you didn’t understand any of this, try reading this again, and maybe try reading up on the concepts I’m talking about on the internet. TimeEmperor signing out!
Enlightning Science 