1960 sci fi novel Dorsai imagines a future world where humans have interstellar transportation, but messages can only be sent once a day and combat communication is via whistles and hand signals. I also have been reading Battlefield Earth, the poorly written sci fi novel that started Scientology. It also imagines a future with interstellar travel and nearly free energy, but communication is via handwritten letters and other very slow methods.… read more “Sci fi imaginings”