That is true.
But, if knowledge of Vedas and Upanishads could be rationally explained then those would not be Sruti. To upanishadic sages, vijnana is science of divided consciousness in contrast to jnana which is wisdom of indivisible consciousness. The latter cannot be known through divided consciousness.
The UR -- the Ultimate reality, the author talks about is just a pointer to Brahman that science cannot measure or explain, since it is Brahman that is seeing, knowing and explaining.
One should not stop at reading Chapter 14 but should proceed further and especially to Chapter 16.