and if someone claimed to know of our universe but provided fabricated and false evidence you would likely not believe them.  if they quoted a book that purported to be the true word of our universe but it was not, you would likely not believe them.  If there was zero evidence of the existence of our universe and a very strong likelihood that you would ever encounter our universe then it likely wouldn't affect your life and you probably wouldn't have an issue with not believing in it and your life would be the same.  Except for those guys who wake you up on a Saturday morning to tell you the real truth of the universe you'll never see and likely doesn't exist
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if they showed it to you, you would likely change your mind