The art of writing great science fiction is that it challenges theimagination, pushing it to extreme limits and in this anthology, selectingsome of the best modern science fiction from the last fifty years, twentyleading authors of the genre ask the question 'What if...?' and then givetheir own very personal views of the changes and surprises which maybefall humanity in the centuries to come. In Ulla, Ulla Eric Brownrecounts the first manned Martian expedition and discovers that H. G.Wells may have been right after all. In The Infinite Assassin Greg Eganpolices the dimensions, seeking those who are taking over their alternateselves. Geoffrey A. Landis takes us into the depths of a black hole inApproaching Perimelasma. Is the ultimate Utopia heaven or hell? RobertSheckley finds out in the classic A Ticket to Tranai. These and otherstories by James White, Eric Frank Russell, Robert Reed, H. Beam Piper andH. Chandler Elliot make this one of the most entertaining andthought-provoking science fiction anthologies in lightyears.