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I wonder whether this has all happened before
In The Matrix movies, the story is that every that everything that happened had happened before. It was revealed that Keanu Reeve's character, Neo, had already lived and died at least a dozen times before. Each time led to a "rebooting" of the system, as the Machines continued to enslave humans as living batteries. It was a complete shock to the human resistance hero when this was revealed to him; there were no clues that the previous incarnations of the world had ever existed, every time the human race "rebooted" it completely wiped out all traces of the previous civilization.
Then reading "Wired" today, in an article about mass extinction, i wondered what would happen after humans became extinct. The world has been here for millions of years before the first mammal, before the first human existed, it's logical to assume that the world will be for millions of years once we are all gone. Either through a meteor strike, or perhaps a giant flood ala the apocalyptic movie, "2012", or any other millions of ways, our days were numbered the moment we breathed our first roughly 50,000 years ago.
The dinosaurs roamed the earth for millions of years before us, and they were wiped out too under unknown circumstances (there are a lot of theories, but no one knows). And, according to Bill Bryson's, "A Short History of Almost Everything", less than 0.01% of what existed during those days of giant beasts are known today. Despite roaming the earth for millions of years, we have skeletal records of barely nothing, just a few dozen different species. Millions of years from now, will there be anything left of us today to speak of or discover.
If that's true, then the opposite can be true as well. In the roughly 4.54 billion years the Earth has been alive, who is to say, the last 50,000 years of human history has not occurred before, but we just don't know anything about it because traces of it have been completely erased by the ravages of time. Even if we continue to exist for another 50,000 years before something happens to wipe us out, our total history of 100,000 years is not even a hair on the camel's back of how long the earth has been in existence. The human race could have been wiped out and rebuilt again a dozen times, just like in the Matrix and we wouldn't know about it.
The truth is, we know next to nothing about what happened on this planet before we existed, and obviously we'll know absolutely nothing about what will happen to this planet once we're gone. God and religion aside, that's a very weird thought to have in your head.