I love how people keep going on about multiple universes and time travel creating new ones and such. As though it were all true, no less! Countless (near-)identical copies of our universe indeed...
No, I'm not saying it must be untrue. I'm just calling the whole mess rubbish until we, as a people, know better (assuming we ever do, of course).
I'll also add that the truth is probably far weirder than our collective daydreams in this thread. For your consideration: I doubt any of us would've imagined quantum theory before some clever physicists started working it out.
Yes, it may well be rubbish but it is the nature of the human race to develop un-natural theories to how things are done.
For example, there are many people who still believe god created the Earth however dinosaurs have been proven to predate humanoid life by millions of years making the theory extremely improbable. Until something is proven, mankind will always believe there is something supernatural to it until proven otherwise by scientific minds.
Not to say god doesn't exist but the bible is incorrect in many of its citations of world events if they are taken as reality and not metaphors.
To say that each time journey would result in a new dimension is an improbable theory that likely is the advent of watching too many sci-fi/fantasy media works. When I created the thread, the intention was to proclaim the Earth's death down to logic that time travel just hasn't been invented because nobody was able to invent it yet, meaning that sometime in our future; we are exterminated or at least thinned down in number enough so that it doesn't exist. I believe there is nothing impossible, just things that haven't been made possible yet and since we don't have time travellers from anyone in our future, that leads me to conclude that we don't reach that technological stage.
You are correct in saying that I have no proof that 500 years will be our downfall but it is the most logical guess if you take into account that within 100 years we have effectively massively increased our capability to act as a society, rather than a group of individuals through technology and that it is extremely likely with the same number of major technological boosts we've had the last century that in 500 years time, we would have the basis of time travel mastered for time is a simple enough theory that is made only complicated by the need for physical technology - something within our grasp but not yet.
Just as the vaccine for what has always been saw as unpreventable has been developed in its initial stages, we will find the initial technology required for time travel sometime in our future, if we live that far and by time we are able to use it, the human race will likely be extinct.
(The bolded part refers to the HIV vaccine that is under development, something that was always seen as impossible to control.)