Now this is another thought that has a lot of implications. If this were true, that means all those time travel movies like Looper, Hot Tub Time Machine, Back to the Future, and even the new Avengers movie would be impossible. And, truth be told, after I came up with this, how those movies approach the concept of time travel became really really annoying. So if you don't want to be constantly annoyed by their interpretations of time travel and just enjoy the movies as they are, then please do not read on. Or you can just learn how to turn off your brain. That works too. It's just want I do after all. Endgame was just too good to pass up.
To understand how I came to this conclusion, you have to first identify what time actually is. Popular media sees time as a separate thing that we move through as if it's a river that has a set path with a before and after. They describe it as the "arrow of time". Wikipedia describes it as the progress of existence and events. Even things like the ideas of fate and destiny seem to play into this by saying that things will happen a certain way no matter what you do as if the future is already preordained. Because of these concepts that time is set or already written or whatever, we get the conclusion that with certain technology, magic, Delorean, or Pym particles as in Endgame, we are able to manipulate our position in that time stream to do whatever.
That's probably wrong, or most definitely wrong if what I came up with turns out to be true.
Time is not a separate thing from space. It does not exist as record of events or whatever. In fact, the term space-time is literally used to describe the effects of gravity and light speed travel. Just by the existence of that term in the scientific community, it's obvious that space and time are connected, or more likely one and the same.
In fact, time can be thought of as a quality of space, a dimension of space if you will. We already know the three obvious dimensions of space: width, length, and height (or x, y, z). So time could be seen as a 4th dimension in additional to the other three. Actually, this is one of the more prevalent views of what time is so I'm not going to take credit for that but I can build on it, though I don't know if other people have already thought of this (read the disclaimer).
To better understand how time works in relation to the other three dimensions, let's take a look at an object: the Moon.
The position of the Moon in space is its three dimensions. We have to clarify what the Moon is in relation to though. Let's say the Earth for simplicity's sake. It's current position above Earth would provide us with the three dimensions of x, y, and z, which then you can plot on a graph paper. But the Moon is constantly moving around Earth, right? And how do you graph that? That's right: by create a 4th dimension that plots the next position the Moon occupies a second later (or minute or hour or whatever). Thus time as that 4th dimension can be seen as the change in the numbers of the other three dimensions.
So what does that mean? It means that time is simply the change of the position of an object in space. If you are familiar with higher level mathematics, time is delta (Δ), aka the change of a variable. Just as change is a quality of the variable so too is time a quality of space. You cannot separate the two.
In essence, the passage of time is simply the collective change in position and state of every particle and energy of every object in the universe. So what we see as a singular event in time is not one single thing.
This line of reasoning can explain (a bit) why as the speed of an object increases, time for it slows down.
First, we have to clarify what the time of an object actually means. Time for an object is not necessarily just its position in space we understand it in the conventional sense. We have to look a bit smaller in the atomic and subatomic. Because of the simple fact that while an object may be standing still, the atomic and subatomic particles that make up the object are still moving. In essence, we have to examine the change in position of every basic component of matter of an object to measure its time. Which is why when measuring the position of an object, we have to clarify what we are measuring it in relation to.
Using the Moon as an example, if it becomes frozen in the sky, its position in relation to Earth is no longer changing. But Earth is still moving around the Sun and the Sun is still moving around the galaxy center and the galaxy is moving through in the blackness of space. So, in essence, though the Moon is frozen in its position relative to Earth, it is never actually frozen in relation to an absolute position in space and it's never frozen in time.
Now back to my explanation of why time for an object slows down as it approaches the speed of light. The speed of light being the maximum speed matter can move through space.
First of all, now that we understand the concept of time (assuming that I'm right of course). the faster an object moves through space, the faster it is changing. And similarly the faster the subatomic particles that make up the object is moving along with the object. So when the object is moving at the speed of light, it's not that time has stopped for it. It's simply that all the subatomic particles that make up the object can no longer move relative to each other.
To better clarify what that means, think of this example from Futurama. The Planet Express ship was going at maximum speed when it accidentally shot Bender from its cannon. So Bender was going faster than the maximum speed of the ship, making it impossible for the ship to catch up.
Now, let's say that the ship was going at the speed of light. Is it then possible for Bender to be fired from the cannon and reach a speed faster than the speed of light? The answer is no. Similarly, when the object is already moving at the speed of light, the particles that make up the object cannot move any faster, even if only in relation to each other. So essentially, the movement of the object through space is like the Planet Express ship and the particles that make up the object is like Bender. The particles have already reached the maximum rate it can change through space and it becomes frozen in relation to other particles within the object. In essence, it becomes frozen in time from the perspective of the object.
This raises an interesting question of then why an object starts slowing down before it even hits the speed limit of matter. And this can be explained by the fact that it takes more energy to move an object through space the faster it goes, and it takes an infinite amount of energy to move an object at the speed of light (remember this because we're coming back to this point). So just as it takes energy to move an object through space, similarly it takes energy to change a particles position relative to each other. When an object as a whole is already moving at a certain speed, to change the position of the particles within the object relative to each other would require more energy. And within the closed system of an object, there is only a finite amount of energy available. Which means that the energy requirements of the particles of an object accelerating is also increasing beyond the ability of the energy of the closed system of the object to provide for it. So the rate of change of the particles within the objective relative to others would have to slow down to compensate.
That means that when an object is already moving at the speed of light, which requires an infinite amount of energy (as we have previously stated), it would require even more energy than that to move the individual particles of an object in relation to each other. Thus they become frozen in relation to each other, and thus frozen in time (but not really since its position in space is still changing).
So that's my explanation for how accelerating to the speed of light slows down time. TL;DR: It doesn't. It just slows down the speed of the individual particles within an object, which makes it look like it slows down time.
Then this raises another question: If the movement of an object through space requires energy to do so, where is the energy coming from that's enough to move the planets and stars through space? Simple. Gravity, heat, and the Big Bang.
The Big Bang obviously was the start of all this and with the massive amount of energy and mass it sent out, it was and obviously is enough to keep everything in the universe moving along even after all this time. Then we have heat. Thermal energy would keep things moving at a molecular level which you can observe just by the fact that the absence of thermal energy would mean that the object is frozen and its particles do not degrade. Finally, you have gravity. Gravity is a strange one since no one is quite sure what it is really. I have some theories myself but that's for another topic. It allows for the movement of celestial objects along with the original energy from the Big Bang. There's probably other sources of energy that ensures the continued change in the positions of a particle, such as electromagnetism but I don't want to go into those too much since I don't know anything about that.
Anyways, we get back to the question of why then is time travel impossible.
If you take into consideration my explanation that there is no such thing as the "arrow of time" or a uniquely separate thing that we exist in, then things are easier to explain. Instead, time is simply a collection of changes that each particle of each object goes through. That means that in order to travel through time, you have to change the dimensions of each particle of each object, along with the corresponding state of energy, in the entire universe to a previous state. Imagine how much energy that would take. If you were to do so with only a localized space, such as the Earth, then you have to calculate the specific position of each particle and energy that comprise everything on the planet as they exist relative to each other. That still takes a lot of energy. But then you would have the issue where everything besides the Earth is in a separate time frame such as the stars, the sun, the Moon, and the other planets. This would cause massive issues with navigation and measurements. Now if you did this with respect to the entire solar system, that might be a bit better but the navigation by the stars and corresponding sciences would still be messed up.
Also you'll notice that my prior discussion hinged on the phrase "relative to each other". If we used the absolute position of a particle in space to change time on Earth, we'd disconnect ourselves from the solar system and the galaxy due to that fact that we are constantly moving through space even as we speak. Then our last absolute position in space as of a second ago is some thousand or million million miles in another direction. That's not to mention how you would even calculate our absolute position in space considering the universe is constantly expanding at a rate faster than light.
So, in conclusion, it is not possible to travel through time because time doesn't work like that. So no, we would never experience anything like time travelers coming back to visit us. This is why no time travelers ever show up to a time traveler's party.
In terms of popular media, movies like Back to the Future or Looper would be impossible as attempting anything like what they describe would require a near infinite amount of energy that no flux capacitor would be able to provide. This would also mean that something like jumping back in time to change your own past would be impossible since doing so would require you to move the particles that comprise you to a previous state as well, and you can't do that since the particles that make up you are in you right now. This renders the entire premise of a lot of time traveling movies entirely moot as the time traveler would not be able to meet their younger self.
Interestingly enough, this also means that the movie, Dr. Strange, has the best interpretation of the manipulation of time in its depiction of the time stone. Spoiler alert. Towards the end of the movie, Dr. Strange uses the time stone to reverse the damage that was done to section of the city by the bad guys and it's shown as reverting the damaged buildings and injured people to a previous state. If you think of it as simply moving the particles and energy states into a previous configuration, it makes perfect sense. It even makes sense that the time stone would have enough energy to make such changes to a localized space. Good movie.
What this means is that in order to bring something to a previous state in time, you must be able to reverse entropy. And the only record of anyone being able to do that is God.
Okay. I think that's pretty much everything. That's a lot to handle but time and time traveling is a complicated subject so maybe this clears some things up.
Or I could be completely wrong about this whole thing. Who knows.
