Review of Ringworld (1970)
Larry Niven (writer).
Read in 2018.
A megastructure in space.
Physics-heavy soft SF adventure and good clean fun. The little cliffhangers are exaggerated, the sexual politics are pretty bad, the idea of luck as a subconscious superintelligence that magically rearranges the world through observably improbable events is unappealing, and I do not like the conjecture that anatomically modern humans seeded the Earth with chimpanzees and everything, which is proposed to account for how the Ringworld civilization can be fully human; this is at odds with archaeology and represents a wasted opportunity to have one of Niven’s cleverly designed alien species building the Ringworld.
I appreciate that the downfall of the Ringworld civilization is analogous to The War of the Worlds (1897), but I do not buy the conclusion that its downfall would be so complete and irrecoverable just for lack of raw materials, when everyone is surrounded by high-tech artifacts created by people for people who can at least build solar cells, train each other, extend their lives and emigrate to one of the old worlds Prill used to patrol.
As with a similar, smaller-scale megastructure in The Black Pillar (1963), the Ringworld would not be stable in its orbit under natural forces. One must suppose that both structures are stabilized by small interventions.