> If you traveled from one end of the universe to the other, no time would have elapsed for you. But the universe would have existed for 13.8 billion years. <
I believe that is correct. It would have taken no time for that photon. And the distance it travelled would also have been zero, from its point of view.
But here’s the thing. Einstein said that an object gains relativistic mass as it speeds up. So an object with mass (like you) would have a huge mass as it approached the speed of light. You could never reach the speed of light (as a photon could) because there would not be enough energy in the universe to get you to that speed.
That’s the way I was taught. But then again I’ve never received a Nobel Prize in Physics. So what do I know?
Thank you for your response. I was using a very small “you” as a way to personalize the experience. As you say, if the light rider had > zero mass it would be impossible to get to light speed. Technically, no rider is really necessary on the photon . But suppose the rider (if present)could get to
99.999999999999999999% of light speed, the local travel time could be close to instantaneous.The implication is that light doesn’t have a time frame. It is timeless..