If ever an empire benefited from keeping its citizens eyes glued hopefully on the horizon, it was the USSR. Hence, Soviet sci-fi was a popular genre in all media. San Francisco's Pacific Film Archive's "From the Tsars to the Stars: A Journey Through Russian Fantastik Cinema" offers a wonderful three-week sampling of its cinematic aspect (Russian sci-fi lit is a whole other area worth scrutiny), stretching from the silent era to the end of Communism. Dennis Harvey reports.