> And let's say, i travel one light-year at the speed of light, that should be instantaneous, right? Time slows down for the faster moving particles. And by ti

> And let's say, i travel one light-year at the speed of light, that should be instantaneous, right? Time slows down for the faster moving particles. And by time slowing down we mean all the particles in your body equally all start to move slower and more sluggishly in sync. This is because it takes more energy to accelerate a particle as it approaches the speed of light. So if you had a pendulum clock moving almost at the speed of slight, that velocity of the pendulum at rest would be at X m/s, but if the whole system is already moving super fast the extra X m/s would take too much energy. So since the energy is constant the relative speed of the pendulum just becomes much slower.