The special theory is different than the general theory of course. The speed of light is finite, and nothing goes any faster, yet light (photons) from distant galaxies may travel billions of years to reach Earth observers. The relationship of time and mass are interesting to consider. Photons supposedly have no mass, therefore photons experience no time in-themselves. Photons exist within electro-magnetic fields phenomenally.
For me at least it is easier to think about photons and the special theory within the general theory of relativity paradigm. Gravity also travels at the speed of light. That suggests an implicit relationship between photons and gravitons as if they were identical. At the least one wonders why gravitons are limited to light speed; what other factor enters in and constrains them? Time is a relationship between configurations of mass from micro to macroscopic and cosmological. Change in the configuration is time. As one approaches light speed mass becomes increased to infinite. It's all quite interesting and full of reciprocal relationships.
For me at least it is easier to think about photons and the special theory within the general theory of relativity paradigm. Gravity also travels at the speed of light. That suggests an implicit relationship between photons and gravitons as if they were identical. At the least one wonders why gravitons are limited to light speed; what other factor enters in and constrains them? Time is a relationship between configurations of mass from micro to macroscopic and cosmological. Change in the configuration is time. As one approaches light speed mass becomes increased to infinite. It's all quite interesting and full of reciprocal relationships.
