This isn't how it works. As you approach the speed of light acceleration becomes less effective (i.e. you feel 1g but don't get faster at 10m/s^2). The interes

This isn't how it works. As you approach the speed of light acceleration becomes less effective (i.e. you feel 1g but don't get faster at 10m/s^2). The interesting thing is that it's actually easier to calculate in the spaceship's reference frame. The two relativistic distortions cancel out and the Newtonian calculation gives the correct answer. So if you accelerate for the first half of your journey it takes you sqrt((28500000040/2)/(365246060*9.81/2)) = 6 years, and the same amount of time to decelerate, meaning 12 years in total.