How we cite our quotes: (Chapter.Paragraph)
Quote #7
"I have made calculations based on what we know about the Stardrive, and using the firmly established results of the Relativity theory. From the viewpoint of the passengers on one of the Overlord ships, the journey to NGS 549672 will last not more than two months […]." (12.16)
The Overlords' science might as well be magic for how advanced it is, yet the novel has plenty of examples of real scientific laws and theories to keep it bound to reality. Here we have Einstein's Relativity theory, specifically drawing from what's called the Twin Paradox. Yes, that's a real thing, but we'll let Neil deGrasse Tyson take it from here.
Quote #8
Nothing in the realm of the supernatural, thought George, could be more eerie than the plain scientific fact that though almost ten years had passed since he had spoken to Jan, that now-far-distant voyager would have aged by only a few days.
The universe was vast, but that fact terrified him less than its mystery. (16.6-7)
One of the qualities that prevent George and his generation from ascending to the Overmind is this mentality, the fear of the unknown. Hard to explore those unknown, far reaches of the universe when the mere idea of doing so freaks you out.
Quote #9
"As you doubtless know, Sir, one of the great problems of our culture has been the dichotomy between art and science. I'd very much like to know your views on the matter. Do you subscribe to the view that all artists are abnormal?" (17.32)
Childhood's End is all about science—no question there—but it's got a lot of love for the arts, as well. See, the Overlords can pursue scientific inquiry and so can people, yet only humans can create works of art. As such, it's not the artist that is abnormal to the pure-reasoning mind of the Overlord, it's humanity. Period.