I enjoy a serious political debate just as much as the next person, but every once in awhile I like taking on something more akin to science fiction. Today, I will argue against the popular belief that someone couldn't go to the past and kill their grandfather; or, if they did, they would cease to exist.
I believe that if time travel were possible, that I could not only go to the past and kill my grandfather, I would still live after doing so, because time is linear.
As such, my Time Theory is simple: Past Actions > Present Actions > Future Actions
Let's look at the famous example of a man going to the past to kill his grandfather, using my theory. If someone went to the past and killed their own grandfather, the grandfather would indeed be dead, but the grandson would still exist (more on this aspect later).
Basically, the action of killing the grandfather in the past takes precedence over even the birth of the grandson in the present or future. And the grandson would not disappear. Why? Because he exists in the past and therefore his existence in the past takes precedence over the future repercussions of his actions, even his non-birth.
Even if he were to return to the future, he still would not cease to exist. After all, why would he? His presence in the past proved his existence. Therefore, his moving forward in time would not negate that fact. His moving through time, in fact, guarantees his existence during any time period that he travels to!
The only problem would be that when he traveled to the future again, no one would know him, since in that Time/Space continuum he was never born, never met his friends, never got the job he had, never married his wife, etc.
TIME TRAVEL RULE #1: If you travel to the past, make sure you have a DVD of home movies showing your wedding, stuff at work and movies of all your friends. Why? Because you would paradoxically, but quite literally be a man (from a parallel universe that no longer exists anywhere but in his memory) without mother, father or even BIRTH.
Again, my Time/Space Theory: Past Actions > Current Actions > Future Actions
"Parallel Universe" is the description of a Time/Space continuum that no longer exists outside the memory of a person or persons. Time is linear. It cannot be used in any other context. Even if you believe in "anti-time" (effect and cause instead of cause and effect) it works.
The traditional view of parallel universes states that any time a divergent action is caused other than normally what happened in the past (Joe walked on the left side of the street instead of the right), then an alternate or "parallel universe" is created. That is not correct.
"Parallel universe" is simply the description of a Time/Space continuum that no longer exists outside the memory of a person or persons. It is human vanity to believe that one person manipulating an event in the past or present can create a copy of the entire universe.
Think about it: the proposition of this theory requires you to somehow believe that if you go to the past, changing one thing would literally create (down to the molecular level) another universe, with another exact set of STARS, PLANETS, PEOPLE, etc???
As any scientist knows, such creation would require a near beyond belief expenditure of energy and there is nothing in the "Parallel Universe" theory that explains :
1) Where this energy comes from
2) How it is expended and
3) Why / how it precisely duplicates the known universe with the exception of one event (and therefore, the resultant consequences)
"Ah," one of you says, "The energy that transported you to the past is what makes the change."
That adds even MORE problems:
1) There is not enough energy in such a transfer (There is not enough energy on Earth to duplicate the entire universe)
2) The energy transference is not linked directly to changing a past event. (i.e., the energy isn't related to the fact that Johnny walked on the left side of the street instead of the right and even IF it were, how would that cause said energy to duplicate the universe?)
"Parallel Universe" therefore can only be recognized as a term used to describe the memory of how the universe used to be, no more.
That all being said, I make no claims to be a physicist and would not be insulted if a physicist were to prove me wrong. Don't forget; comments are welcome.