Answer:
The total time is
.
Explanation:
Given:
The distance between Galactic Capitol and Earth is, 
The speed of light is, 
The time taken by the message to reach and come back to Earth is given by

In addition they take 1 year to decide to reply.
Thus, the total time is
.
It can never be shorter than a component - magnitude of a vector is the square root of the sum of the components squared, and a square function never produces a negative number. However, it can be the same size as it's component, if that component is the only one.
False. Gravity was always here but no one really thought about it until Isaac Newton did.
Potential Energy = mass * 9.81 * height
(9.81 is the acceleration due to gravity on Earth)
PE = 6 * 9.81 * 6 = 353.16 J