Time travel is one of the most fascinating ideas springing from the human mind. A very popular trope for science fiction fans; it has been developing a following among the scientific community. There is a conflict among scientists as to whether or not Time Travel is possible. Luminaries such as Stephen Hawking, Carl Sagan, Robert L. Forward and Frank Tipler have given explanations as to why it can’t happen or how to possibly do it.
Dr. Hawking asks that if time travel into the past were possible why we don’t see tourists from the future all over the place (sort of a temporal version of Fermi’s Paradox). He also wrote the Chronology Protection Conjecture which states that any time machine would immediately be destroyed if it was used. Only transfers of information on the quantum level would be permissible.
Dr. Sagan said that travelers from the future would disguise themselves so we wouldn’t know they were there.
Dr. Forward posits a time machine made up of a single atomic nucleus under conditions where it might be possible to send information but not matter back in time.
Dr. Tipler developed a theory that a rotating cylinder of infinite length and density would allow travel back to the point of the construction of the cylinder.
With the advancements being made in the field of Quantum Physics and the related study of Quantum Gravity, time travel is now seen as something that can be done at a quntum level. The missing piece of the puzzle is using the theory Quantum Gravity to tie Quantum Physics to Classical Physics. One place I find a lot of information is the site arvix.org; a free website that publishes scientific papers of all sorts. I use it a lot, but the math makes my brain bleed sometimes. Who knows what will happen in the next hundred years of study?
As both a writer and voracious reader of science fiction, I find these types of stories my absolute favorite (along with the variation of alternate timelines and parallel universes – yes, there is a group of scientists working on proving these things exists). From H.G Wells through Isaac Asimov, James P. Hogan, Stephen Baxter, Joe Haldeman and Jack McDevitt these stories always grabbed my attention. From Star Trek to Babylon5, I have hung on every word of time travel in the scripts. And don’t EVEN get me started on Dr. Who! I’ve been watching that show since the Jon Pertwee. I consider myself somewhat of an armchair expert on paradoxes, etc… But the latest Star Trek movie got me thinking even more about time travel. I’ve heard comments about how drastically different things were presented. Not just the destruction of Vulcan, but all of the things that seemed to make up the past were changed. Now, combining my love of science fiction, time travel and Quantum Physics I think I have a handle on this time travel thing. Remember, almost everything from this point forward is a conjecture.
Time travel has happened and is happening as we speak. What I think is being missed is the fact that when you travel in time you are not just affecting yourself, but you affect everything down to the level of quantum flux (not to be confused with the Flux Capacitor from Back to the Future). When you get down to the level of what is called Planck Length (1.616252(81) ×10−35) you are in the arena of quantum foam where everything is in flux. Now, time travel would have to be a high-energy event no matter how you did it. Be it a wormhole, a silver cage, a crystal or a Wayback Machine it will require massive amounts of energy to power the transfer; unless you discover a way to do it with magic, and then all bets are off!
When you travel back in time, the energy you expend to get there has to go somewhere. Otherwise you will probably be instantly vaporized, along with half the galaxy. When this energy dissipates, it will interact with the Universe on the Planck-Level. When you add energy to anything it will change. This change would manifest itself as apparent changes in reality. There are always choices and decisions being made every nano-second; and I’m not talking necessarily conscious, human-made ones. Subatomic particles have their own path to follow and things can change randomly. One energetic particle hitting just right can change the entire timeline by causing a cascade of changes.
And when you appear in the past, you are now embedded again in the timeline; all of your quantum entanglements reestablish themselves and you are now an “Observer”. This means that just by existing you influence reality. Look up the double slit experiment if you want see this in a real world situation of changing the outcome of something merely by observing it. And dealing with high-energy on the quantum level might mean that the energy you release might continue traveling back in time like a bow wave!
So, when the effects of your high-energy arrival in the past you won’t be able to make a killing on the stock market or sports events. Your very existence has changed the course of history, probably for the entire Universe. Maybe because of you,Americalost WWII, or the Revolution. Maybe the changes rippled back so far we’re still pond scum! Hopefully, it won’t come to that!
Even small changes will happen that nobody will ever realize (except maybe you) because everything leading up to the change is consistent with what is accepted as reality after the change. So if you make it back to see people you know they may have entirely different personalities, jobs, families, who knows? Maybe you were never born in this timeline.
The key to this whole discussion is time travel can change things and we will never know, because of the self-consistency of the timeline. Someone in another galaxy could be time traveling right now, and things would change here on Earth without our knowing anything is different. So learn to live with it!