"This is Trantor three centuries from now. How do you interpret that? Eh?" [Seldon] put his head to one side and waited.

Gaal said, unbelievingly, "Total destruction! But—but that is impossible Trantor has never been—"

Seldon was filled with the intense excitement of a man whose body only had grown old, "Come, come. You saw how the result was arrived at. Put it into words. Forget the symbolism for a moment."

Gaal said, "As Trantor becomes more specialized, it becomes more vulnerable, less able to defend itself. Further, as it becomes more and more the administrative center of Empire, it becomes a greater prize. As the Imperial succession becomes more and more uncertain, and the feuds among the great families more rampant, social responsibility disappears."

"Enough. And what of the numerical probability of total destruction within three centuries?"

….

[Gaal] said, "About 85%?"

"Not bad," said Seldon, thrusting out a lower lip, "but not good. The actual figure is 92.5%."

Basic set up:

Hari Seldon, a scientist who has developed the science of psychohistory, reveals to the young mathematician Gaal Dornick that Trantor, the center of the Galactic Empire, is probably going to be kaput in three centuries. Yikes.

The book that inspired Isaac Asimov to write Foundation is a historical work by Edward Gibbon called The History of the Decline and Fall of the Roman Empire. That book about the Roman Empire got Asimov thinking about the rise and fall of civilizations more generally. How and why is it that civilizations peak, and then decay? Why is that decay inevitable, and are there ways to prevent it?

In the passage above, we see two characters talking about the inevitable decline and fall of the Galactic Empire. The Galactic Empire, of course, is just a made up sci-fi empire. But its fate is also an allegory for the fate of the civilizations that us regular folk live in. In other words, in talking about the decline and fall of the Galactic Empire, Asimov is also talking about the decline and fall of our own civilizations—every single civilization—right here on earth.

In the above passage, we can really see the "science" in "science fiction." Seldon has developed a new science, called "psychohistory," which allows him to accurately predict the decline and fall of the Galactic Empire.

The passage, in other words, focuses on science (though of course psychohistory is a made-up science). This emphasis on science and scientific prediction is also reflected in the numbers. Seldon can predict, down to the percentage point (92.5%) the likelihood of destruction of the Galactic Empire within three centuries.