"Everything in the universe was there the whole time."
"Everything in the universe was there the whole time."
Late at night and early in the morning, sometimes even during dreams, I regularly contemplate the meaning and nature of infinity, time and the universe.
Every bit of energy / matter which makes every atom, every electron, every sub atomic particle has always been here since the beginning of this grand time paradox we call the universe.
Since all particles and energy dates back to the beginning of time, they effectively don't change very much. We may move around atoms and energy, and we may split atoms, but it is all effectively dominoes of particles. One grand chain of dominoes from the beginning of time stretching into infinity.
Thus everything in the universe is particles and energy that has been there the whole time, since the beginning of time, and will always be there. All of them are effectively immutable fractions of the universe making up the whole.
The Problem of Time Travel...
Consequently this poses a problem for people wanting to do time travel. It means that in order to go back in time, one would need to take part of our present universe into a separate dimension and then travel through that dimension to a point where they could re-enter our universe at a different point in time.
To do so contradicts the nature of the universe however, which is inherently like a very complicated giant moving clock with every particle and every bit of energy being a tiny cog in the grand machine. Introducing a single new particle or electron changes history and sets off an infinite chain reaction.
Sending a whole person back in time, who is sentient and composed of 7 x 10 to the power of 27 atoms (7 billion billion billion atoms) would set off a huge chain reaction, creating a separate timeline and a parallel universe. Plus the added problem of sending a sentient person back in time with knowledge of history who might attempt to change history on purpose. Even if they avoided trying to change history, their mere presence would set off a huge chain reaction.
Eventually the atoms and energy they brought with them back in time would surpass the point where they originally left our universe to begin their journey back in time. At which point the universe would once more have the same number of particles and energy it has always had since the beginning of time.
Which brings us to an interesting conundrum. What happens if the person in the new timeline fails to go back in time, creating a 3rd timeline? Their particles stay in the new timeline, effectively doubling how many of those specific particles are in that universe.
Time travel is so inherently problematic.
The untold amount of energy needed to leave our dimension and enter another.
Who can say the human body can even survive in another dimension.
Even if someone used a ship to travel through the other dimension, who is to say it wouldn't be crushed like a grape by the physics of that dimension?
Where would they get the untold amount of energy to leave that dimension and re-enter our universe?
How would they know they are re-entering our universe at the desired point in time and space? They could end up in the wrong year or floating in space. After all, our planet is spinning around the sun, and the sun is just a tiny star in a spinning galaxy which is itself traveling through the universe at enormous speed. So by the time someone returns to our universe they could be re-entering at a point in a very different part of our galaxy.
So considering all the problems that time travel comes with, it is best to assume that time travel is probably impossible.