Lets assume I create a spaceship that is powered by vacuum energy which gives the spaceship an unlimited fuel supply. I leave earth at full power and remain at full power forever. I have an accelerometer mounted to the dash just below the fuzzy dice. Will my accelerometer measure my ship accelerating forever? I understand that my velocity measured with respect to any object will always be less than C but I am concerned only with acceleration. My assumption is yes, it will accelerate forever, if not then why?