Question

what was Eco's theory about 'empty spaces'?​

Answer 1

According to Eco empty spaces are very important. If empty spaces are eliminated from the universe, the universe will become as big as a man’s fist.  

Eco calls his free time interstices (empty spaces); he makes best use of them. He writes most of his books in these empty spaces. For example, when he was waiting for Mukund, he wrote a very important article for his book.