You buy a gallon of milk which will spoil in 4 days. However, you know for a face that you will want a glass of milk in 10 days. You put your milk into a spaceship and blast it off at a speed V.
a) What is the minimum speed at which the milk must be travelling such that it is still good when it returns to you in 10 days?
b) How far has the milk travelled in YOUR frame of reference.
c) How far has it traveled in ITS frame of reference?