It's interesting to think sometimes about why things are the way they are and how strange it would be if it were the opposite.  Like, what if instead of outer space being an absolutely cold empty void, what if it was burning hot and we needed super cold ice stars to cool things down to make planets habitable for life?  Or instead of being mostly empty, space was mostly full of stuff?  Just like you could basically walk forever across the entire universe?  

That would be way weird.