These 16 essays from the fifth annual J. Lloyd Eaton Conference at the Univer­sity of California, Riverside, seek to come to grips with science fiction’s core, the core at which “science must ulti­mately seem to outweigh the fiction.”   Never before has hard SF been the topic of such extended discussion by such qualified people. The dialogue con­stitutes new (and potentially shocking to a traditional literary critic) modes of lit­erary criticism, modes that take into ac­count the impact of scientific specula­tion and method on our culture and on the ways our culture invents stories and myths.   Essayists include writer/scientist pro­fessors Robert L. Forward, David Brin, and Gregory Benford. Noted critics and writers with scientific backgrounds or interests include: James Gunn, Frank McConnell, George Guffey, John Hunt­ington, Paul Carter, Patricia Warrick, Paul Alkon, Robert M. Philmus, David Clayton, Eric S. Rabkin, Herbert Suss­man, Michael Collings, and George E. Slusser.