In: Physics
You and your friend Paul want to have a bet on how fast it can take to reach another friend Peter who is near the star Sirius B. Knowing that the star has a proper length of 8.6 light years from Earth, Paul thinks that since the maximum speed of your ship is 70% that of the speed of light, it will take about 9 years to get there. However, you reason that around 12 years will make more sense.
a) Who is right from the perspective of you and Paul?
b) When you reach Peter and explain the bet, he disagrees about who was right, why is that?