One of the most amazing notions that people have explored in terms of science and physics, is the idea of time travel. There is no dispute that going back in time, or forward to the future just for the experience alone would be amazing. With all the technological innovation and advancement that is currently occurring it would seem appropriate that we would already have some sort of idea how to do this, or even be on the verge of making it happen, but sadly that is not the case. The closest we’ve come is in science fiction movies, TV shows, and books. (List of time-travel movies: https://en.wikipedia.org/wiki/Category:Time_travel_films )

Back to The Future is by far one of my favorite movie series not only for the whole adventure aspect, but that the movie paints the picture of the world today as highly technologically advanced with flying cars and hover boards. (since I first saw the movie I’ve wanted a real hoverboard.) The creators of the movie believed back then that we could do all of this, and yet we haven’t. I think this is wholly important because it draws the line between what is science fiction and what’s not. Unfortunately, time-travel is one of those ideas that are looking more and more like fiction every day. There is a variety of theories surrounding time travel, but a large portion of them point toward time travel being practically impossible, for us that is. Yes, I know, it’s the same old story- this awesomely cool thing can only work with super small particles and humans can’t do it because we would die. Here are the methods by which time travel for a particle may be possible, and how we, unfortunately, would die from it:

1. Black holes
   1. Black holes, as I mentioned before, are points in space that are infinitesimally dense and thus drastically bend the space-time fabric.
   2. The method of traveling would involve flying around the rim of the black hole at the speed of light. As time would pass by more quickly for the traveler, upon returning to Earth the traveler would have aged considerably less than those still on Earth.
   3. Flying that fast and the forces that we would feel would no doubt kill us
2. Wormholes
   1. Worm holes are essentially points in the space-time fabric that have been folded on to themselves and will thus provide a gateway between different spots in the fabric.
   2. The wormholes would end up being very small and short-lived and so whatever would go through them would have to be extremely small as well
3. Infinite Cylinder
   1. This idea is based upon a similar concept as the black hole. If you have an infinitely long extremely dense rod, then you can swing around the rod to allow time to pass by more slowly for you.
   2. The problem is again that you would not be able to handle the forces being applied to you.
   3. Plus, you’d need to make this rod.
4. Cosmic Strings
   1. These are either loops or infinitely long tubes of energy leftover from the creation of the cosmos. If two of these were able to get next to each other and be parallel, it is suggested that they would pull the space between them so much so that it would form a small time-like loop like the other scenarios in which time would pass more quickly.
   2. The forces, again, they are too strong.
5. Time Machines
   1. It’s a relatively common idea that traveling through time would need to be facilitated by some sort of machine or device, though not anything like a Phone Booth or a DeLorean.
   2. Most employ the concept of using exotic matter which essentially works in the opposite manner than what matter is generally expected to, but there is so very less of this in the world that it would be rather impossible to gather enough to make a time machine with it.
   3. One concept that may work involves a hollow ball with a donut-shaped interior where strong gravitational waves are inflicted upon the center. The individual would ride along the interior on some sort of vehicle. This mimics the closed time-like loop of the above space options.
   4. The caveat with this last option is that the gravitational fields required would need to be immense and extremely accurate.

If all else fails, these are paradoxes that might destroy us if we did so much as try:

1. Grandfather paradox
   1. If you go back and accidentally do something to hinder your existence, then you would cease to exist or further permanently alter the timeline.
2. Butterfly effect
   1. Even the smallest of changes in the past could have catastrophic changes for the future.
3. Self-consistency
   1. The particles in the timeline prefer to be as they were in the past and so just being there poses an alteration and would thus be impossible.

All in all, it seems like it will a long while before we actually see any real time travel come about, but for now I guess we can make do with just trying to preserve ourselves so we last to see the future. Here is a great article from my favorite website, WaitButWhy.com: http://waitbutwhy.com/2016/03/cryonics.html on Cryonics, a prospective way of more conventional time traveling.