We can prove that we have been here as long as we have and the universe exsisted and is not a product of our imagination because, everything interacts with everything else. The massive craters on Earth show meteor impacts, the geological strata show the various temperature fluctuations, even the present position of hte Sun in our Galaxy demonstrates how we all came into existence. The various supernova that we observe clearly show events of the past that proves that there was indeed a real past and its not all in our heads.
Thats a nice thought!
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