We have NEVER experienced the physical world around us. Everything we have seen, have heard, have smelled, have tasted, have touched...has all be experienced from within our brains. You are NOT seeing these words on a computer screen in front of you, you are seeing these words INSIDE your brain. Anything you see, is in fact, NOT a real object...it is only a representation of that object that is projected inside your brain. The same applied for all other senses. Quite literally, none of us have ever experienced the "real" world around us. Although, our senses have evolved to allow a level that is very impressive.