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I’m trying to find the name of a book in which humans are at war with an alien race. While traveling to the galaxy where the fighting is, humans travel at the speed of light while being kept in tanks of fluid to prevent being injured by the sudden speeding up and deceleration. Whilst they are in transit they do not age but for everyone back on Earth time still goes by and when the travelers arrive at their destination everybody they knew back on Earth had long since passed away.
I do not remember much else about the story but I do remember enjoying the book, can anyone can help by supplying me with the novels name and author?