How does the author use foreshadowing in Foundation and Empire?

In Chapter One, Barr offers a historical account of the establishment of the Foundations. He says that Seldon foresaw the fall of the Empire, and it's at that point that Riose interrupts. He insists that the Empire is stronger than ever and that Seldon's prediction is wrong. Barr goes on to say that Seldon carefully selected two planets at opposite ends of the Galaxy and has carefully selected the people to inhabit each. One of the Foundations was populated with scientists while the other was inhabited with psychologists. Riose plans to visit both Foundations and promises to return. Barr isn't certain Riose will return at all.