Note: the matrioshka brain was first proposed, at least among humans, by Robert Bradbury. Robert, not Ray. Robert was a futurist and transhumanist fascinated by the Great Silence (also known as Fermi's Paradox.) Ray was a futurist and transhumanist fascinated by ignition temperatures for paper.
Liz has conflated the two men. Adding to the confusion, she has also conflated them with Robert N. Bradbury, a prolific screenwriter and director from the early 20th century. His works include Riders of Destiny and Westward Ho, both of which starred John Wayne, who, fortunately for those of us who struggle to keep these things straight, did NOT appear in Farenheit 451.
LIZ: Ray Bradbury was a twen-cen futurist. He had this idea for a giant computer built in concentric shells around a star.
He named it the Matrioshka Brain because it reminded him of matrioshka dolls.
KATHRYN: Oh, those are cute.
CDRE TAGON: Look! They all fit inside the big one.
KATHRYN: Oooh!
KATHRYN: Stellar Enclosure 4118-6 seems a lot less threatening now.
LIZ: It shouldn't, but okay.