"Time" is just the way we think
Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.
("P" stands for "Proposition" and "C" stands for "Conclusion")
Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...
But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?
Any and all helpful criticism is appreciated.
The problem with this issue is that you can't say something cannot happen because it's illogical. In fact, history is full of episodes when actual observation contradicted the logic of the time. The key point here, unseen by many people, is that logic does not apply to reality, it only applies to the way we think about reality. People who believe time travel may be possible are not entirely wrong; however, if what we loosely think of today as "time travel" turns out to be possible, then the skeptics will prove their point: whatever it is, it can't be called "time travel".
Mentat, I suggest your approach to the problem is slightly wrong, because you are not fully taking into account the way we think. Here's how I see the problem:
At any given point in time, I am aware of a certain amount of historical knowledge. One such piece of knowledge is "I did not exist in 1776". This is very much what you say in P1 and P2, with an important difference: the emphasis on "what I know" as opposed to "what is true".
Now suppose "something" happens (let's leave that undefined for now), and suddenly you acquire a new piece of knowledge that says "I did exist in 1776". You have a problem now, because two pieces of knowledge contradict each other. By the way, this is an extremely common occurrence in our daily lives, so the solution shouldn't be that difficult.
Let's examine a somewhat similar situation: At some point in your life, the statement "I have never been to Atlanta" was true. Then another "something" happened, and the statement "I have been to Atlanta" becomes true. Do you have a problem now? Replace "have been" with "existed" and think about the difference between Atlanta and 1776. Particularly why it's possible to be and not to be in Atlanta, while the same cannot be said about 1776. It's very interesting if you approach it from a particular perspective, as it reveals something about time.
The reason you can be and not be in Atlanta, the reason the two pieces of knowledge do not seem paradoxical to you, is because you already know the solution to situations like that. And the solution involves a concept called... time! "Time" is what allows two apparently contradictory statements to be true.
Back to time travel. Can it be possible? I say it can, only not the way you think about it. In order to explain how you can be and not be in 1776, you need the same concept you use to explain how you can be and not be in Atlanta: you need "time". So time travel is possible if you can "travel" through "time 1" using "time 2". In other words, time travel is perfectly possible as long as there are two or more time dimensions.
I suspect a question still remains: can we prove time travel is impossible if there is only one time dimension? And here the answer sounds too obvious to me: if there is only one dimension of time, then you can only travel from 2004 to 1776 by going through every single moment in between. You can't jump from 2004 to 1776 without first going through 2003, 2002, 2001, and so on. Now what happens when you go back through those years? If there's only one dimension of time, you already know the answer.