The so-called Ultimate Fear was Karl's lifelong pursuit and research. It is the concept that no matter how evolved dominant biological civilizations become, they will eventually encounter something more powerful and irresistible. Dominant biological technology cannot surpass it. In other words, the universe cannot accommodate the highest intelligence. If intelligence cannot transcend the universe, it cannot comprehend its concepts.
When Kasha first raised this issue, the Angel civilization had a history of 100,000 years and was the highest-ranking civilization known at the time. But in the slowly flowing river of the universe's history—which spans 1.3 billion years—it is absolutely impossible for only one Angel civilization to have emerged! Either those civilizations were obliterated without a trace, or they exist beyond our cognition, within spaces we cannot explore.
