Interesting, but the point remains that the answer is different from the 8 years mentioned given that you do have to accelerate up to near-c (at gees the human

Interesting, but the point remains that the answer is different from the 8 years mentioned given that you do have to accelerate up to near-c (at gees the human body can survive in) and then decelerate from it. You can't just instantly go up to near-c and then back down to zero. Whether it's special/general relativity that's necessary for this calculation, it's a materially different result.