There has got to be a simple formula for space travel. Light is a element or force ( what’s it’s label?) That cannot be bound by time boundaries.Once Light leaves the limits of 365 earthdays (a light year) or any of the planetary clocks, how fast does it travel?
Imagine the Universe as a pond, The Galaxies are rocks in the pond we hop from rock to rock to cross the pond. Within each rock light is slowed down by Time & gravity. Once light escapes time frames & Objects of Gravitational mass it starts to leap from place to place "Light just Is", it can’t live or die it does not fade away it’s always moving and arriving from one place to the next. Gravity and Time allows us to capture light as if it were in slow motion. Without Gravity & time (which is only present within a solar system and the Galaxy, within the great year: one complete swirl of the Milky Way) there is no time limit or over baring gravity in the blackness of void therefore light can travel in a blink of an eye.
there are some theories that state that the universe can bend through dimensions, so that basically light can go from one side of the universe to the other in a second. in this theory, we can also say that if we are not within distance of touching something, that object could be on the side of the universe, and if we get closer to it, then we could also have gone to the other side, by way of dimensions. i dont know the names of these theories, but basically they assume that the universe it not flat(but rather bent and can move), and that the universe not only has 3 spatial dimensions + 1 dimension of time, but even more. string theory suggests 26 dimensions.
light is considered masslass, if it were to travel faster than light (like theoretical tachyons) it could rip spacetime and create a wormhole. its all theory.