How far can we push time dilation and can we use it as a "time ship"?
You have an interesting question concerning time dilation. Here are the facts about time. Time is not physical and similarly time dilation has no power to change anything including the motion of a spaceship. Time and time dilation are just the numbers that are displayed on a clock. thats all. You cant time travel with time, or on time, or any other thing that you can think of. Time is merely a measurement of motion, or events. Furthermore, time doesnt make sense after a spaceship leaves earth. Time is a man made invention that only exists on earth. To base the motion of the universe using our invention of time is a falsehood. In your question you dont care about the health of the spaceship crew, but they would not survive a long time. It seems that mankind is not meant to leave our solar system. We have more than enough work to do on earth without wasting time and energy on space travel. I hope you feel the same way.