Gaal can't tell whether it's day or night underneath the metal sky of Trantor.
That really must be a weird feeling, like living inside a planetarium.
He heads to the Luxor's lobby and tries to buy a ticket for the planetary tour. But like any family vacation ever, he just misses the departure.
At least he doesn't have a spouse to give him those "I told you so" looks.
Instead, he buys a ticket for the observation tower.
The elevator is a fancy bit of tech running off gravity repulsion. I.e., you are free of gravity while it moves upward. Gaal's newly found weightlessness leads to some antics on the way. Thankfully, a stranger helps him manage.
When they get to the observation deck, it's just Gaal and the stranger. Gaal can see the entire planet, nothing but a giant metal infrastructure as far as the eye can see. No green, no animals, nothing that could be called nature. Sounds very, um, gray.
The stranger introduces himself as Jerril. He talks to Gaal about how no one in Trantor ever comes up to the observation tower. Apparently, if you live your entire life inside the tin can that is Trantor, then the idea of open sky can give you a serious case of the heebie-jeebies.
Jerril asks Gaal what brings him to Trantor. Gaal answers that he's received a job offer from Dr. Seldon. Raven Seldon?
Actually, yes. Raven Seldon is Hari Seldon's nickname, since he's always predicting disaster.
Gaal is irritated that Jerril is badmouthing his idol, so he heads back to his room.
In said room, he finds another stranger waiting for him, but the man doesn't remain a stranger for long. It's Hari Seldon.
Encyclopedia Galactica: This time the entry is on psychohistory.
The basic idea is that a mathematician can predict the future using psychohistory's formulas. But there's a catch: you need a lot of people. The larger the sample, the more accurate the prediction.
So, if you want to know if two planets will go to war, then psychohistory will serve as your Magic 8 Ball. But if you want to know if your girlfriend will breakup with you, no can do. Sample size is just too small.