BTW, if through some combination of a great starting spot, perfect play, and miracle you can take over one or two civs and get most of your science from them, that's great
actually no - at least 1/3 usually close to 50% of your scicne will come close to allways from NC cap - if u do things right ...
getting beyond these 4-6 own cities for some ai cap is viable on every difficulty lvl
On deity all u have to do is ally 2 M CS or so and maybe upgarde 3 archers all their path - like that taking few deity cities is no problem at all ..
just need make sure they got some unique lux or happynes will become a problem soon ..