All the can or can’t aside, I’m curious of how long it would take to reach the speed of light when maintaining an ACCELERATION that would put a constant 2g on the body. I would think that certainly be a cardio workout if it took an hour. I guessing 3gs for an hour might kill a person. I really haven’t a clue though.
Using Special Relativity, any constant acceleration places “you” ( or the accelerated object ) on a hyperbolic trajectory wrt any inertial frame of reference.
So, a laser beam, say, turned on at time “t=0” , when you begin accelerating and placed at a certain distance “behind” you, will never catch you ... i.e. you will never see it, even though you never exceed “c” in this frame.
It’s all simple algebra.
Take it with a grain of salt, but I get 36 days.